Category: Climate change and gardening


Hawthorn has been spotted in flower at New Year, a whole five months earlier than expected Alamy

Hawthorn has been spotted in flower at New Year, a whole five months earlier than expected Alamy

‘It’s unheard-of: after the warmest and wettest December on record, more than 600 species of British wildflowers were in bloom on New Year’s Day 2016, a major survey has shown.

In a normal cold winter, botanists would expect no more than 20 to 30 types of wild plants to be in flower in the British Isles at the year’s end – species such as daisy, dandelion and gorse.

But a survey by the Botanical Society of Britain and Ireland (BSBI) has discovered that on 1 January, no fewer than 612 species were actually flowering, including some from late spring and high summer – an occurrence which seems to be without precedent, and has left plant scientists astonished.’ For more read the full article here.

 

Old School Gardener

One Billion Hungry: Can We Feed the World?

ID-100383599Making small changes can have a big impact so this January do away with impossible-to-keep resolutions and do something that can make the planet greener, help local or distant communities and save you money. Make the change for over 66 days and, according to Lally et al (2010), it could become a new habit.

  1. Help tackle climate change

World leaders agreed the Paris Climate Deal in December, but tackling climate change will take all our efforts, not just politicians and big business. The transport sector in the EU is responsible for about one fifth of greenhouse gas emissions so help reduce this by taking public transport, combining trips and flying less (somewhat easier now with the rise of video/conference calls). The energy sector is responsible for almost 30% of emissions and so being more energy efficient is an important goal across industry and society. Learn how to make your…

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Scylla- '4 weeks late'

Scylla- ‘4 weeks late’ in 2013

‘Everything’s four weeks late’. So said my friends and fellow gardeners Derek and Mary Manning in April last year (we were just emerging from the coldest winter in 50 years). This was when I wrote this last article in the series on gardening and climate change.

You might remember Mary from my first article in the series. She’s the Norfolk gardener who’s been keeping records of when certain plants first flower each year – for over 60 years in fact.

Over that time she’s seen a gradual creeping forward of when some spring flowers do their stuff, so supporting the evidence from elsewhere that the overall climate is warming in the UK and that Spring is starting earlier…. Yes, you did read correctly, spring is starting earlier! That is until 2013, when all the expectations flew out of the window as we had our coldest March for 50 years and, as any UK gardener will tell you, most plants were holding off until the real Spring arrived. The Manning’s evidence in 2013 showed that Scylla (the lovely purply- blue woodland bulb) flowered on the 4th April in 2013, almost exactly a month later than in 2012!

Why do I share this information with you? Well, if you’ve been reading my previous articles in this series you will have gathered that recent events in the UK’s weather (and further afield) seem to be prompting some rethinking of the theories and forecasts of climate change and it’s expected effects.

In my first article, I set out what the forecasts currently are and how these seem to be changing, so that unexpected or abnormal weather events (prolonged periods of unseasonal cold,wet or drought) seem to be increasing in their frequency and impact on gardeners – and everyone else. This could mean that we need to set aside notions of ‘lateness’ in flowers blooming or not, as the age-old certainties of what and when the different seasons happen is changing.

How can we gardeners cope with this increased unpredictability? My second article talked about how we can prepare the garden for this sort of uncertainty – how to create our own, managed ‘micro climate’ if you like. In my last article I talked about how this preparedness needs to be complemented by a watchful, vigilant gardener – I call him/her the ‘Constant Gardener’. A way of gardening which is tuned in to what’s happening in the short to medium term and can take remedial action to further ameliorate or take advantage of the weather we get.

This article is the final piece of the jigsaw, so to speak – what sources of information and intelligence are already open to us and that may possibly develop in the future? In short, how to ensure that as well as being well prepared, watchful and diligent we take advantage of all the information we can to better judge what we do and when in the garden. I want to cover the following topics:

  • Weather forecasting –  can we expect longer range forecasting to improve, to give us the forward view we need of how particular seasons are going to go?

  • Plant hardiness and quality are there any systems for judging and ranking plants to help us?

  • Pests and diseaseswhat early warning systems are there to help us prevent the worst effects of these in our gardens as the seasons roll on?

Warm if not sunny

Weather – can we expect seasonal forecasting to improve?

Back in April 2013 here in Norfolk we were forecast (I nearly said ‘promised’) rain over night on two occasions. This failed to materialise so I had to adjust my plant moving plans a little and the continuing dry weather meant I could get on with other weather dependent tasks in the garden. I have to say, I wasn’t that surprised as here in eastern England the progress of easterly tracking weather fronts can often promise rain, only for this to peter out over the rest of the country before we see any benefit. This day to day uncertainty is to be expected and to be honest I can probably live with it, as the weather forecasts, including their useful ‘severe weather warnings’, are generally reliable enough.

If I were overly anxious or wanting to plan things on almost an hour by hour basis the Met office’s ‘Nowcasts’  use radar to look a few hours ahead. Particularly useful for those harvesting waste water on an agricultural scale as well as extreme weather events involving potentially damaging hail, strong winds and lightning, I could look these up and plan my activities to the minutest degree.  What I really would value though, is a longer term picture of what the next few months or weeks are likely to hold weatherwise. Not surprisingly, it’s this sort of forecasting that proves to be the most challenging as it involves monitoring and then predicting a number of variables and is particularly difficult in the UK because of our position on the globe. As the Met office explains:

‘Our one-day weather forecasts are right six days out of seven, and today’s four-day forecasts are as accurate as one-day forecasts were 30 years ago. While this shows great advances in reliability, we cannot always predict detailed differences in weather at a local level.

This is because the atmosphere is an extremely complicated system, affected by a huge number of factors and with the potential to react in endless different ways. To ensure completely accurate forecasts at all times, we would have to greatly increase the amount of observations we get so they cover every part of the planet, every minute of the day. Even then, a supercomputer far more powerful than anything in existence today would be needed to simultaneously process all this information into forecasts.

We are not there yet, but as we increase the number of observations, the complexity of the models, and the power of our supercomputers, forecasts should get more and more accurate.’

Online Weather services hold awide rnage of information and 'outlooks' for the month and season ahead

Online Weather services hold a wide range of information including ‘outlooks’ for the month and season aheadOf course it doesn’t help matters when the media gets hold of these longer term forecasts and makes simplistic and crude statements like ‘scorching summer predicted’ and so on.

This just discredits the longer term forecasting with all its hedging around with probabilities, if’s and but’s. The Met Office defended it’s work on long-range forecasting following criticism of its forecasts for the Spring and summer of 2012, when exceptionally wet weather hit the UK.

It concluded:‘We are confident that long-range outlooks will improve progressively and that the successes we have achieved in other parts of the world already will, in the future be mirrored in the UK. The Met Office constantly reviews the accuracy of our forecasts across all time scales and is recognised by the World Meteorological Organization as one of the top two national weather forecasting services in the world….Better understanding and representing the drivers of predictability in the global climate system that influence our weather patterns is as ever a priority for Met Office research in order to deliver improved advice and services on all timescales.’

Further comment  came in a reply to my specific questions about longer range forecasting and gardeners. Dave Britton of the Met Office said:

‘The provision of longer-range forecasts is extremely challenging and always will be for the likes of NW Europe and the UK, where only small changes in driving factors can have a big influence on pressure patterns, wind direction and therefore our weather. However the science of longer range forecasting is improving and just as we have seen huge improvements over the last 40 years or so in the provision of 3 to 5 day forecasts, we will see similar advances in long-range forecasting in the future too.’

The position in North America appears to be somewhat more predictable, though even here there have been exceptional weather events in recent years which may point to a more uncertain future. The larger-scale, continental climate here seems to make it easier to predict things like first and last frost days in different parts of the US and Canada, something that the Met Office doesn’t do, mainly because  the weather in the UK is much more variable.

So, apart from hoping that longer range forecasting will improve what other weather data can the UK gardener use to inform his timings and techniques? For fruit and veg growers a critical factor is air and soil temperature for germination and planting. Maybe we need to be even more aware of what’s needed for different types of plant- see the examples of this sort of information below.

Plant hardiness and quality – what systems are there to help us choose plants that perform and are resilient?

Another area of information we gardeners can use to cope with weather relates to plants themselves – their hardiness, resilience to particular extreme conditions and other qualities. In the UK the Royal Horticultural Society has reviewed both its plant hardiness and ‘Award of Garden Merit’ systems. The new plant hardiness system is now temperature based (instead of classifying the UK into four geographical hardiness zones which was the basis of the previous system).

Now plants are being put into seven categories from glasshouse plants (H1) through to plants which are ‘fully hardy’ (H7). The RHS Director of Horticulture, Jim Gardiner says he is conscious that in the UK plants have to contend with other factors than temperature when looking at ‘hardiness’ – the condition of the plant itself, prevailing climatic conditions, growing conditions, position in the garden, age, provenance and so on. We also have temperature swings to contend with (RHS – ‘The Garden’, February 2013). So I guess there is a recognition that this hardiness guide (which is currently limited to the plants in the RHS Award of Garden Merit scheme) has its limitations.

But, as Jim Gardiner says, it is a system which is plant, not place – based (like the US Department of Agriculture Winter Hardiness Zone approach – see the map below). So, it is perhaps more useful for the UK gardener, where our maritime context and variations in temperature and associated growing conditions can be much more localised (as well as increasingly unpredictable) than is the case in such a large continental land mass.

SIMP_All_states_fullzones_300dpi

USA Winter Hardiness Zones

USA Winter Hardiness Zones

The other main plant rating system in the UK – the ‘Award of Garden Merit’ –  is also run by the Royal Horticultural Society, and began in 1922. It received a complete overhaul in 1992 and a ten yearly review cycle resulted in a new list being compiled last year. In addition, following plant trials or round table reviews by plant committees and specialists, new awards are made every year. The ten – yearly reviews ensure that every variety is still available, hasn’t developed disease or pest problems, and hasn’t been superseded by something better. In the 2012 review, for example, the crab apple ‘Comtessa de Paris’ replaced ‘Golden Hornet’, which can suffer scab. In the 2012 review of the nearly 1000 vegetables holding the AGM, 404 were no longer available, so they have been deleted from the list.

The AGM is intended to be of practical value to the home gardener and is awarded only to a plant that meets the following criteria:

  • Excellent for ordinary use in appropriate conditions – a cultivar or selection that outperforms others, perhaps for more flowers, length of flowering, scent, colour, form etc.

  • Available to buy

  • Of good constitution – the plant should be known to be generally healthy

  • Essentially stable in form and colour – it should perform according to its description

  • Reasonably resistant to pests and diseases – it should have no pest and disease issues that would affect growth and performance

Rudbekia laciniata 'Goldkugel'-  in the RHS AGM list and considered to be fully hardy (H7)

Rudbekia laciniata ‘Goldkugel’- in the RHS AGM list and considered to be fully hardy (H7)

Rudbekia laciniata ‘Goldkugel’- in the RHS AGM list and considered to be fully hardy (H7)

Just because a plant has an AGM, does not mean it will do well when poorly looked after. A large number of plants hold AGMs at any one time. The current list (which includes the plant hardiness rating) contains over 6000 ‘ornamentals’ and 1000 ‘fruit and vegetable’ varieties and is used in plant gazeteers such as the RHS ‘Plant Finder’ which lists where plants, including AGM holders, can be purchased. A similar system operates in the US, the ‘All American Selection’ (AAS), which is slightly younger and somewhat different to the AGM. The judges and the trial grounds vary from year to year and four categories are judged: Flower, Bedding Plant, Vegetable, Cool Season Bedding Plant, and only never-before-sold varieties are tested.

So, the new and updated systems of plant hardiness and quality look like being useful sources of information for gardeners considering which new plants (or maybe replacements) to grow in their particular location and with an eye on future weather extremes. And it is no accident that some experts are starting to identify plants that can withstand particular climatic extremes, like flooding.

Potato blight- early warnings of its spread for 8 years in the UK

Potato blight- there have been early warnings of its spread for 8 years in the UK

Pests and diseases – can we get early warning of possible problems?

Finally, it is clear that some (if not many) pests and diseases can flourish in different weather conditions. Is it possible to predict how different pests or diseases might affect your garden so that you can take the necessary preventative action? In the UK there are some useful ‘early warning systems’ especially for food growers. For example there is a system for potato blight, which is prone to develop in damp, warm conditions.  The Potato Council has offered a blight incident reporting service for 8 years. This information is collected on a voluntary basis by 300 ‘blight scouts’ drawn from members of the potato industry who are routinely walking potato fields during the season. You can sign up to be alerted about blight with the Potato Council.

You can  sign up for early warnings of the spread of aphids

You can sign up for early warnings of the spread of aphids

You can sign up for early warnings of the spread of aphids

The UK Horticulture Development Company Pest Bulletin provides early warnings of potentially damaging pest attacks and valuable advice for planning this season’s planting of fruit and veg. Providing information throughout the key periods of pest activity, the HDC Pest Bulletins are updated on a regular basis, especially when particular insects are developing rapidly.The HDC also produces a Pest blog.

The UK  Home Grown Cereals Authority (HGCA) also produces a weekly regional ‘aphid alert’ which you can sign up to. All these systems have their value, but I’m not aware of any system that draws them together for gardeners on a regular, regional basis. Perhaps this is something the RHS might coordinate, incorporating the latest weather forecasts and advice about particular issues affecting different plants?

To sum up, there are already a number of sources of information and intelligence available to the gardener that can help ensure a successful garden. Some of these – e.g. longer term weather forecasting and pest and disease warnings  – would clearly benefit from further investment and coordination. These can  be put alongside measures to prepare your garden for unpredictable weather and adopting an approach to gardening which is ‘watchful and diligent’- the constant gardener. It will also be interesting to see the results of the RHS- University of Reading survey of gardeners and climate change models when it is published- hopefully sometime in April 2014.

Together they give me optimism that the gardener of the future will be well equipped to cope with climate change. And we mustn’t forget the importance of adopting sustainable gardening practices as well as a positive move to reduce the ongoing impact we have on global warming and its fuelling of further climate change.

rain measuring boots

One way of monitoring water levels?!

One way of monitoring water levels?!

If you have any comments on these ideas or have some of your own, I’d love to hear from you!

Previous articles in this series:

Four Seasons in One Day (3): Climate Change and the Constant Gardener

Four Seasons in One Day (2): Preparing the garden for climate change

Four Seasons in One Day (1): Climate change and the garden

Further information:

Top pest and disease threats in Britain

RHS Science Strategy

Dig for Victory- how your garden can help beat climate change

Watering advice

Wikipedia- Tiwanaku

Sir John Beddington’s warnings on climate change

Britain like Madeira?

My Climate Change Garden

UK Meteorological Office – impacts of climate change on horticulture

Royal Horticultural Society – gardening in a changing climate

‘Gardening in the Global Greenhouse ‘ – summary

RSPB- guide to sustainable drainage systems (download)

RHS guide to front gardens and parking

Old School Gardener

If you’ve enjoyed reading this post and others on this blog, why not comment and join others by signing up for automatic updates via email (see side bar, above right ) or through an RSS feed (see top of page)?

 

constant gardenerIn this third article about climate change and the garden (originally published in 2013), I set out some ideas on how the gardener can manage the day-to-day garden environment and other short-term measures to modify the impact of abnormal weather events. As previous articles have outlined, these seem likely to become more frequent  as a result of the warming of the planet and associated climate changes around the world.

I think it’s fair to say that effective gardening in the future will rely on gardeners:

  1. Being well prepared for abnormal weather events  and taking steps to change the design, planting and systems in the garden to cope (the subject of my previous article)

  2. Being aware of, and using, a range of information about the weather, plants, pests etc. (I’ll look at these issues in my final article), and

  3. Developing gardening skills and techniques as well as a flexible, ‘can do’ attitude – or what I’m calling the ‘Constant Gardener’ –  the subject of this article.

‘Constant’ implies dependability, ongoing attention and responsiveness,  qualities that the ‘climate change gardener’ will need if the gardens of tomorrow are to be as productive, beautiful and healthy as today. Just like Justin Quayle’s ‘gentle but diligent attention to his plants’ in the film of the same name, in fact!

The focus of the Constant Gardener is on how those annual and biennial plants that we raise from seed can be nurtured and protected from the worst excesses of the weather. However, attention to how perennials, shrubs and trees are faring will also require vigilance throughout the year and possibly remedial action, if the weather threatens to harm a particular plant or area of the garden.

So, what can the Constant Gardener do?

A moveable awning or sun shade like this could help to protect tender plants from the hottest part of the day
A moveable awning or sun shade like this could help to protect tender plants from the hottest part of the day
  • To cope with periods of hot sun, consider temporary shades that can be moved around the garden to provide protection for tender plants where there is no natural shade – e.g awnings slung between posts which can be moved to shade beds or borders at risk from ‘frying’. I mentioned the value of permanent structures like pergolas and arbours in my last article.

  •  To ensure successful nurturing of plants from seed, sow in smaller quantities and in successive batches – especially if you’re growing food, where successional sowings will in any case give you (hopefully) a steady supply rather than a glut followed by nothing.

    Sowing seeds in small batches at different times of the season can help to thwart the impact of abnormal weather - especially on food crops

    Sowing seeds in small batches at different times of the season can help to thwart the impact of abnormal weather – especially on food crops

  • Carry out plant propagation and nurturing under cover and in frost free spaces ideally you will have in place a variety of growing conditions, light frost-free rooms in the house, greenhouse/conservatory and cold frame – make sure you use them effectively to harden plants off before they are fending for themselves outside.

  • Choose plants – especially fruit and veg – from varieties that you like to eat and which are resilient or suited to the sorts of conditions you’ve created in your garden and the weather extremes that seem likely (though this itself may be increasingly difficult to predict). For a ‘belt and braces’ approach, grow a few different varieties if you’re not sure about the best ones for you and your garden. Your choice may also mean that you’ll need to compromise  a bit on quality as a trade – off for resilience.

  • If you’re buying plants, be vigilant about pests and diseases  – with increased plant mobility between countries as well as an increased geographical growing range for some species, the risk of importing pests and diseases is increasing.

  • Delay sowing if your soil is slow to warm up – early sowing is a gamble where the odds are against you, whereas sow a little late and the odds will probably shift in your favour.

  • Be prepared to accept failure and learn from it for next time. Keeping records of seasonal weather, the varieties grown and how they fared is invaluable when growing food crops.

  • If there’s a choice, opt for growing quick food crops – this way there’s less time for them to be affected by abnormal weather.

    Radishes are a quick growing crop

    Radishes are a quick growing crop

  • Remember the ‘transfer window’ – make sure you prick out, pot up and pot on regularly, before plants give up the ghost or succumb to ‘damping off’. Aim to grow a few strong plants rather than lots of weaklings!  This will make for better resistance to pests and diseases.

  • Rotation plus – you’re probably aware of the importance of moving your food crops around the garden to avoid the build up of pests and diseases associated with one family of fruit or veg, as well as moderating the drain the plants put on the soil’s fertility. The Constant Gardener should also consider successional sowings of the same crop in different parts of the garden if possible (what you might call ‘Divided Bed’ gardening) and if you want to be ultra cautious you could use different varieties too!

    Horticultural fleece can be a quick way to protect young plants from overnignt frost
    Horticultural fleece can be a quick way to protect young plants from overnignt frost
  • Protect young plants against frost – use fleece, cloches or other temporary covers

  • If plants have suffered from a wet/flooded winter, give them a spring feed, mulch over the root area and give them a foliar feed during the growing season to build up their strength.

  • Use water harvested from wet periods (in butts, barrels or tanks) to water effectively in dry times. Use pipes and ‘SIP’ plastic bottle feeders plunged into the ground to ensure water gets straight to the plant’s roots. Avoid using sprinklers and hoses as much of the water they deposit on the surface of grass or earth evaporates. You could go for a green solar -powered watering system like the one in the picture!

    A solar-powered water harvesting and distrbution system
    A solar-powered water harvesting and distrbution system
  • Over – winter tender plants in containers in an inside, well-lit and frost-free room or greenhouse, conservatory, or cold frame (ideally with insulation and the scope for added heat when necessary). If they can’t be moved out of the ground, mulch with  suitable organic material to protect the roots, and for some wrap up the stem and branches with fleece or similar material.

    Some larger, tender plants will need to be wrapped up for winter
    Some larger, tender plants will need to be wrapped up for winter
  • Keep glasshouse, conservatory and cold frame panes clean to maximise sunlight.

  • Look after wildlife and they’ll look after your garden. Feed birds in tough winter spells and create habitats through planting etc. to attract beneficial insects and other ‘critters’ that will keep pests at bay.

  • Avoid using power tools and equipment if at all possible as these will contribute to the emission of CO2 either directly or indirectly and so fuel global warming.

    Keeping greenhouse glass clean helps to maximise sunlight

    Keeping greenhouse glass clean helps to maximise sunlight

So, to sum up

  • Constant awareness of what the weather is bringing you and your garden

  • Constant willingness to act in the short-term as well as being prepared

  • Constant action to propagate, nurture and protect your plants!

If you have any comments on these ideas or have some of your own, I’d love to hear from you! My final article will look at plant awards, hardiness ratings, pest and disease information and the future of longer term weather forecasting as ways of keeping the gardener well informed.

Previous articles in this series:

Four Seasons in One Day (2): Preparing the garden for climate change

Four Seasons in One Day (1): Climate change and the garden

Source:

‘Monty’s Garden’– article by Monty Don, Gardeners’ World Magazine, January 2013

Further information:

Dig for Victory- how your garden can help beat climate change

Watering advice

Wikipedia- Tiwanaku

Sir John Beddington’s warnings on climate change

Britain like Madeira?

My Climate Change Garden

UK Meteorological Office – impacts of climate change on horticulture

Royal Horticultural Society – gardening in a changing climate

‘Gardening in the Global Greenhouse ‘ – summary

RSPB- guide to sustainable drainage systems (download)

RHS guide to front gardens and parking

Old School Gardener

If you’ve enjoyed reading this post and others on this blog, why not comment and join others by signing up for automatic updates via email (see side bar, above right ) or through an RSS feed (see top of page)?

 

drought-headerThe impacts of climate change on gardening around the world are becoming clearer, though of late perhaps the emphasis has shifted away from global warming, the associated changes in the onset and duration of the seasons and the conditions for growing different plants. The recent focus has been on prolonged extreme weather events like peristent wind and rain in the UK, drought in pacific north America and ice and snow in the mid west and eastern seaboards.

In this second of a series on climate change and gardening I’ll set out a few ideas for ‘being prepared for the unpredictable’.

I originally wrote this article in March 2013, whilst looking out on a sunny but cold day – temperatures were hovering around freezing and a biting easterly wind reduced the temperature feel by a few more degrees. The ground was cold, spring flowers were struggling to make headway and some of my seedlings were battling to stay alive, let alone get to the potting up stage!

Once again, this year in my part of the UK (central Norfolk), we seem to have escaped the worst of the most recent bout of severe weather. Elsewhere in the country where there was deep snow on the ground last year (some drifts were over 4 metres deep and there was talk in the press of ‘the coldest March for fifty years’ and ‘the longest winter since 1962’), this year, as Spring knocks on the door, we’ve had a relatively mild winter, but one which has brought severe flooding, wind and other storm-related damage (such as ‘sink holes’) to many parts of the UK.

Professor Sir John Beddington
Professor Sir John Beddington

As the retiring UK Chief Scientific Advisor, Professor John Beddington warned in an interview last year:

“The [current] variation we are seeing in temperature or rainfall is double the rate of the average. That suggests that we are going to have more droughts, we are going to have more floods, we are going to have more sea surges and we are going to have more storms…These are the sort of changes that are going to affect us in quite a short timescale”

So, it looks like many (if not most) gardeners face the challenge of seasons tipping between unusual weather patterns including long periods of drought, flood and frost.

Wild flower meadows can be a more sustainable option than frequently mown lawns.
Wild flower meadows can be a more sustainable option than frequently mown lawns.

My first article in this series about climate change and gardening looked at what the forecasts said, based largely on models of climate change produced about ten years ago. Last year the Royal Horticultural Society and University of Reading linked up to publish a new research report  which is based on new forecasting models and which includes the results of a survey of gardeners on what they perceive to be happening and what measures they have already taken or are preparing to take. This survey revealed that two-thirds (62%) of British gardeners feel optimistic that they can adapt to the challenges climate change may bring, while 70% believe changes in gardening practices can help them garden successfully in a changing environment.

So, we all know that in the short term we can do certain things to avoid the worst excesses of the weather and I’ll be reviewing these in my next article. In this post I want to set out a few ideas for some more strategic measures we might take to ameliorate the impact of abnormal weather events.

So, what are we trying to achieve?

It might sound obvious, but I guess we’re trying to create the right growing conditions for the plants that stand a good chance of growing (if not flourishing) in what are the underlying climatic conditions for where we live. 

In the UK, ‘maritime climate’ is a disarmingly simple term which refers to what can, at the best of times, mean very variable weather conditions from region to region and from month to month. Overlay the effects of climate change on this and the (unexpected) variability can be that much greater. We need to look at ways of managing and manipulating the ingredients for growing success – or if you like, putting in place measures that can maintain the right ‘micro climate’.

This is nothing new. The Romans harvested winter rains for use in their parched summer gardens. The ancient Tiwanaku people of South America developed an ability to manage the growing environment for their crops. They lived between Lake Titicaca and dry highlands in present – day Bolivia. The area near the lake provided key resources of fish, wild birds, plants, and herding grounds for llamas. Further to the east in the Altiplano area is a very dry, arid land. Here, the high altitude Titicaca Basin provided less promising growing conditions and resulted in the development of a distinctive farming technique known as ‘flooded raised field’ agriculture (suka kollus).

 

This consists of artificially raised planting mounds separated by shallow canals filled with water. The canals supply moisture for growing crops, but they also absorb heat from solar radiation during the day. This heat is gradually emitted during the bitterly cold, frosty nights, providing ‘thermal insulation’.  Over time, the canals were also used to farm edible fish, and the resulting canal sludge was dredged for fertilizer. The fields grew to cover nearly the entire surface of the lake and although they were not uniform in size or shape, all had the same primary function. Though labour-intensive, suka kollus produce impressive yields. Significantly, experimental fields recreated in the 1980s by Alan Kolata and Oswaldo Rivera of the University of Chicago suffered only a 10% decrease in production following a 1988 freeze that killed 70-90% of the rest of the region’s production.

So, as we can see, the Tiwanaku engineered fields that were specialised in coping with seasonal variations and were able to ameliorate otherwise frosty local conditions. It is this sort of approach – ‘working with nature’  rather than attempting to control it – that is the key to coping with the impacts of abnormal weather events in our gardens.

What can we do to get our gardens prepared for climate change?

home made compost
Home made compost – try to create as much as possible to improve soil structure and fertility

Soil

  • Organise home composting and leaf mould creation, if at all possible. Organic matter added to all types of  soils will improve water absorption, aeration and fertility. Double (deeply) dug beds with plenty of organic material incorporated will be a great help. Likewise adding gravel to heavy soils can help to loosen up the structure.

  • Add mulches of organic materials to beds to help conserve moisture or otherwise use ‘cover crops’ to avoid areas of bare earth which will dry out more quickly.

  • Raised beds will provide well – drained growing conditions  and an annual layer of organic material may be all that’s needed to keep the structure and fertility up to scratch (and can be extended further with alternating layers of different materials such as newspaper to keep weeds down and improve structure and moisture retention when needed – so called ‘Lasagne gardening’).

  • Make sure you adopt ‘healthy practices’ when preparing growing media and containers so that you minimise the risk of harmful diseases – wash out pots and seed trays. And remove all those little potatoes from a plot where you grew these to avoid encouraging blight.

Rain gardens can provide a solution to gardens with excess water
Rain gardens can provide a solution to gardens with excess water

Water

  • Don’t pave over large areas of open ground for parking, patios or other reasons, unless the materials used are permeable to allow run off. Likewise use permeable materials for paths such as gravel, bark chippings or in combination with pavers and/or ensure runoff into surrounding beds and borders if the ground can take the surge of heavy rainfall.

  • Could your garden (or perhaps an area of lawn) benefit from improved drainage? Apart from installing a system underground, you can improve aeration and absorption in lawns by annual spiking with a fork (or if the area is large a mechanised version of this) plus scarifying the surface with a spring rake. Better still, reduce the area of lawn or remove it altogether – in  some areas people have replaced even front garden lawns with food growing beds.

  • For temporary flood protection, try ditching the boundaries of your plot to hold and possibly divert excess water to places where it can be better coped with – for instance you could create a pond or pool to capture excess water and possibly also provide a ready source in times of drought and help to attract beneficial wildlife to help control pests. And think of the Tiwanaku and their frost preventing raised field planting – creating bodies of water near frost pockets can help to reduce the impact of cold weather.

  • Look for opportunities to use excess water to add new planting areas to your garden – bog or rain gardens where planting can be adjusted to make use of the wetter ground conditions. See this link for further ideas on storm water management.

  • And alongside this have water harvesting measures in place to capture rainwater so that it can be stored and used when needed – barrels, butts or tanks fed from downpipes – even underground storage tanks are now available.

  • Consider using weeping hoses, automatic irrigation systems or simple measures like short lengths of pipe/open ended plastic bottles inserted in the ground alongside plants to ensure watering is efficient, reaching the roots rather than evaporating on the surface.

Efficient watering can be simple
Efficient watering can be simple
Make your own greenhouse from recycled plastic bottles
Make your own greenhouse from recycled plastic bottles

Temperature

  • Think about the mix of planting you have and if hot weather is likely to be an issue, ensure that shorter, smaller, more sensitive plants are sheltered at the hottest time of the day by some shade from other overhanging trees, shrubs or other planting.

  • Likewise, more permanent structures such as pergolas, arbours and the like can provide not only an interesting growing feature but can provide shade for plants underneath or along their edges.

  • Greenhouses, polytunnels, conservatories and even light rooms in the house (where temperature and humidity can be controlled) can provide a protected environment for over – wintering plants that would otherwise perish in cold spells. Heating your greenhouse adds greater flexibility, and can be ‘green’ if you harness the earth’s thermal energy through some sort of simple heat exchanger that taps warmth below ground.

  • Use cloches, larger plant covers or cold frames to provide mini controlled environments which can enable germination of seeds, development of seedlings and possibly protection of less than hardy plants during times of frost or prolonged cold. The growing season (especially for food crops) can effectively be extended through such methods. See this video for information.

wind breaks can reduce the impact of strong winds

Wind breaks can reduce the impact of strong winds

Planting

  • Use wind breaks of trees, hedges, other planting or permeable barriers of suitable man-made material fixed to posts to reduce the speed and force of winds which can cause dessication (drying out) of plants  as well as structural damage. These measures can be used on the boundaries of the garden as well as inside it to create pockets of  still air which can also raise temperatures.

  • Choose plants which can cope better with weather extremes; look out for indicators of resilience on plant labels and especially accreditations such as the RHS ‘Award of Garden Merit’ (AGM- I’ll be covering this in more detail in my final article of the series).

  • Plant for the future, using trees, shrubs and hedges that are drought tolerant or damp-loving – whatever is suited to the conditions in your garden or parts of it.

  • Avoid long-term planting in flood areas, unless you are trying to create different growing conditions like bog or rain gardens.

  • Avoid clearing slopes of vegetation as this may cause erosion problems.

  • Encourage biodiversity and beneficial wildlife through your choice of plants (as well as the other measures that you can take to create different habitats) so as to help control unwanted pests. Planting a native species hedge for example can encourage wildlife and provide shelter from drying winds or storms.

  • Think about increasing the proportion of perennials you grow, including fruit and vegetables, as these are less demanding of fertility and CO2 emission in their propagation etc.

A garden pond can help with capturing excess water and improve biodiversity

A garden pond can help with capturing excess water and improve biodiversity

And finally, think sustainably when considering the overall impact your garden and gardening practices will have on the world. Gardens are enormously valuable in the fight to reduce CO2 emissions and by reducing or removing the use of powered tools (especially those used in lawn maintenance) we can further increase the beneficial impact we have.

In my next article in this series I’ll turn my attention to gardening techniques and short term measures we can take to manage the impact of abnormal weather patterns. In the meantime, if you have any direct experiences of climate change or any other comments I’d love to hear from you.

Other articles in this series:

Four Seasons in One Day (1): Climate change and the garden

Further information:

Wikipedia- Tiwanaku

Sir John Beddington’s warnings on climate change

Britain like Madeira?

My Climate Change Garden

UK Meteorological Office – impacts of climate change on horticulture

Royal Horticultural Society – gardening in a changing climate

‘Gardening in the Global Greenhouse ‘ – summary

RSPB- guide to sustainable drainage systems (download)

RHS guide to front gardens and parking

Old School Gardener

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droughtI’m now back from very enjoyable visits to the Scottish Hebrides islands of Mull and Arran as well as Northumberland and will release some posts about this over the next couple of weeks (along with some photos I’m rather pleased with…).

In the mean time how about a brief relook at gardening and climate change?

I originally published a series of four articles about gardening and climate change in 2013. Today’s reports of a strong ‘El Nino’ effect in the next couple of years coupled with man-made global warming look set to bring about some more dramatic weather events, albeit the results in the UK might be a little gentler than typhoons and droughts (2015 and 2016 the warmest years on record and maybe a cold winter? -we can’t be sure…).

With this renewed interest, I thought I’d republish the series of four articles over the coming days (apologies to those who have already read these). Today’s understanding of and predictions about climate change do not seem very different to those I was writing about two years ago…

In this first of a series of posts about gardening and climate change, I explore just what the experts are predicting for the UK and what this might mean for our current gardens and gardening techniques.

I think it was Nietzsche who said that madness comes not from uncertainty but certainty. But for the gardeners of Britain, pulling their hair out in the face of ‘the wrong weather at the wrong time’, climate change and the unpredictable weather it is bringing us can frustrate even the most seasoned horticulturist, though perhaps stopping short of madness! It poses significant challenges to gardening customs  and practices, which have in the past been based on the predictable passage of the seasons within fairly certain timings and within, by and large, expected bounds of temperature, wetness, wind and frost (though in the maritime setting of the UK these can all vary considerably from area to area). So maybe we need to look upon these greater levels of uncertainty as a challenge and one which will actually be mentally stimulating!

The underlying changes have already begun to unfold in the UK (and elsewhere):

  • A gradual, overall rise in average temperatures

  • Increased frequency of extreme weather events like rain and flooding, frost and snow, wind or drought

drowned cars aus

A few years ago a seminal article on the impact of climate change on gardening in  the UK (‘Gardening in the Global Greenhouse’ by Richard Bisgrove and Paul Hadley of the University of Reading) pointed up these trends and started the debate about what they will mean for Britain’s gardens. The main conclusions were:

  • reduced frosts

  • an earlier spring

  • higher average temperatures all year round

  • increased winter rainfall, leading to increased risk of flooding 

  • hotter, drier summers, leading to an increased risk of drought.

FloodedGardenMayCredAdrianBloom_L

They pointed to how these trends were likely to make looking after large areas of lawn and grass increasingly difficult and costly, and how some traditional garden features may have to be replaced by new ones, more suited to changing conditions (e.g. loss of some ‘cottage garden’ favourite plants). Arguably there is even a greater challenge for heritage gardens, which have traditionally featured large lawns, herbaceous perennials and specific planting combinations and effects which were developed in climatic conditions that will gradually disappear.

It also seems that there’s something of a north – south split in the UK, with the south becoming warmer and drier and the north subject to wetter weather, in the winter especially, though recent storms and flooding in the south west and southern Britain might seem to run ounter to this trend.

On the plus side, botanic gardens have had to be intensively managed in order to grow the widest possible range of plants in ‘living collections’ and these highly managed environments may provide scope for growing an increased range of plants, as increased temperatures and the other key trends take effect. Botanic gardens are also in a key position to promote and spread knowledge on climate change and its effects.

In gardens more generally, plants are also grown in very favourable conditions:

  • propagated in controlled conditions

  • planted into carefully prepared ground

  • protected from pests and diseases and competing plants

This should give us some optimism that the techniques and conditions for responding to climate change are already well developed and gives the garden an advantage over nature.

frosted plant

Though rather slow and insidious, it is already possible to detect some of these trends. The Central England Temperature Record shows that between 1750 and 1900 (150 years) the average temperature in Central England increased by 1 degree Fahrenheit (0.7 degree celsius). During the 20th century this trend advanced faster so that the average temperature rose by a further 1.5 degrees Fahrenheit with two thirds of this increase happening since the 1970’s.

This record also shows how 5 of the 6 warmest years since records began in 1659 occurred in the ten years 1989-99. The prevalence of frosts has also declined: an average of 55 frosty days in the 1880’s has reduced to about 35 days by the 1980’s. And closer to home, here in Norfolk, a local gardener has kept records of when certain plants started flowering in her garden from the 1960’s to the 2000’s. Mary Manning’s records show the advancing of Spring: Winter Aconites began flowering in mid January in the 1960’s and by 2000 this had moved to mid December. The same is true of Hazel, which first flowered around the beginning of February in the 1960’s and has likewise moved to before Christmas in forty years.

Global CO2 levels seem to be rising by about 1% per annum, though predictions of the future rate and impact of this inevitably vary according to assumptions about economic growth, reductions in carbon emissions and other factors. But although these underlying trends seem increasingly accepted, we also seem to be getting freak frosts, floods or droughts of varying length and intensity – almost at any time of the year, making the normal weather patterns of the seasons less and less ‘normal’.

Looking at the underlying trends, the impact of climate change on our gardens will most likely be determined by factors such as plant hardiness and tolerance of excessive wet, or drought conditions (see the chart for one forecast of reductions in water availability across the globe). This poses a challenge to the gardener’s ability to drain land or supply water as needed.

the-contribution-of-climate-change-to-declining-water-availability

The British Meteorological Office points up some of the other potential impacts:

  • ‘Increased carbon dioxide levels will increase rates of plant growth and perhaps development (bud burst, flowering and leaf fall)

  • Changes in temperatures are expected to bring an earlier onset of growth in spring and a longer growing season

  • Mild winters may reduce the yield of fruit trees, because colder temperatures are needed to break the buds

  • Increased temperatures will aid the growth of more plants from warmer parts of the world

  • Higher temperatures and decreased summer rainfall will cause stress, especially in plants with extensive, shallow, fibrous root systems

  • Annual moisture content of soils is likely to decrease by 10-20% across the UK by the 2080s, with substantial reductions (of 20-50%) in soil moisture possible in the summer by the 2080s

  • Fungal diseases will thrive with the wet winter conditions.’

Old School Garden in the snow

So, as gardeners we have to cope with both the longer term trends (which arguably will not be very noticeable in the short term) and, perhaps more importantly, increased frequency of unpredictable, extreme weather events of uncertain length and impact. This ‘seasonal uncertainty’ is perhaps our greatest challenge as well as trying to use gardening practices which help to reduce CO2 emissions and are broadly sustainable.

Over the last four decades, extreme weather events have severely damaged many gardens and resulted in major economic losses. These events include:

  • Severe winter weather in 1962/63 that killed many hardy plants

  • Drought in 1976, which weakened trees and dried out lakes

  • Storms in 1987 and 1990 that felled millions of trees

  • Torrential and prolonged rain leading to soil erosion, flooding and drowning of plant roots in 2000, 2001, 2007, 2012 and now 2014

As Monty Don says,’The number one rule remains the same: do not fight nature’ (Gardener’s World Magazine, January 2013). He goes on to observe how ‘the past couple of years have been noticeable for the wrong weather most of the time’. We do not yet know if a new weather pattern (which is another way of saying climate or ‘average weather’) will establish itself , or whether we are in for ever more uncertainty. Or perhaps that’s just it – ‘the one certainty is that the weather will be more uncertain’ and we need to adapt our gardening techniques and habits to cope. As Monty says,

‘Expect the unexpected and be flexible’

So, lets look upon these new circumstances as a challenge to our gardening skills and respond to nature’s call. In my next post on climate change I’ll be looking at the advance measures we can take to better prepare our gardens for the unpredictable and longer term impact of climate change. If you have any direct experiences of climate change or any other comments I’d love to hear from you.

Further information:

Britain like Madeira?

My Climate Change Garden

UK Meteorological Office – impacts of climate change on horticulture

Royal Horticultural Society – gardening in a changing climate

‘Gardening in the Global Greenhouse ‘ – summary

Old School Gardener

If you’ve enjoyed reading this post and others on this blog, why not comment and join others by signing up for automatic updates via email (see side bar, above right ) or through an RSS feed (see top of page)?

Stunning Underground Garage Design Ideas With Hydraulic SystemMy friend Les sent me this link to an item on BBC News, which makes for interesting, if not surprising and worrying reading…

Old School Gardener

 

Orchard-PerspectiveGo to these links for a fascinating look at different Architect’s visions of the future of farming…

http://www.economist.com/blogs/multimedia/2010/12/designing_vertical_farm?fsrc=scn/fb/wl/vi/inventinganewarchitecture

http://http://www.economist.com/blogs/babbage/2010/12/vertical_farming

Old School Gardener

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