It’s that time of year to get some seeds sown and new growth underway- but how do you ensure your new babies stand the best chance of survival? Here are some ideas for your ‘transfer window’- turning your newly born into successful seedlings…

1. Right pricking out time

For seeds sown in trays or small modules, once the seeds have germinated and you can see growth above the soil, keep a close eye on their leaves. Once the first ‘true’ leaves have formed (these will look more like the final leaf of the plant and follow on from the ‘seed leaves’ that are simpler in shape, like those in the picture above) it’s time to prick out these little seedlings and transplant them, usually into pots or larger modules. If you leave the plants longer they risk becoming spindly and overcrowded as they fight for what little nutrients are left in the seed compost.

2. Right tool

You need some sort of thin implement to tease out the seedlings – I find a chop stick or wooden BBQ skewer is useful. Or use a dibber or pencil – but these might be a bit too thick for some smaller seedlings. Gently prise the individual plants out of the compost so that they bring their roots and possibly a little compost with them.

3. Right handling

Gently take hold of the leaves of the seedling to help it on its way – don’t hold it by the delicate stem as crushing this will deprive the plant of its main channel for water and nutrients. Place your plant into a hole big enough to take the roots comfortably, settle the plant slightly deeper than it was in the original seed tray/module.

Watering in the transplants

4. Right Pot

Use clean pots and in general a smallish pot (3″ diameter) or modular tray is probably OK for this stage. A guide is that the pot should be about twice as wide as the roots of the plants you’re dealing with. If you want to avoid several potting on stages and you have the room, then go for a bigger size pot/modular tray. Make sure that you clearly label the plants and possibly keep a note of when you transplanted them.

5. Right compost mix

The compost mix you use for potting up needs to have the nutrients the plant is looking for and the right consistency to allow drainage and air around the developing  roots. You can opt for a particular mix for the plants you’re growing but for most I find a general purpose peat free compost (e.g. ‘New Horizon’) is nice and ‘open’. But it can be improved by sieving (to remove bigger bits of organic material), and adding some horticultural grit or ‘perlite’ in the ratio of 1 part grit to 3 parts compost. Or you can make up your own mix.  If you keep your transplants in the same pot for a few weeks you might need to apply some liquid fertiliser to make up for the nutrients that are gradually depleted from the compost.

A portable greenhouse like this one can be used to grow on seedlings

6. Right environment

Different plants will have different environmental requirements, but in general they need to be thoroughly watered in to their new pots/modules and moved into a light, cooler place than they were in for germination – but avoiding drafts and direct sunlight. For the first few days, the plants might benefit from covering with plastic to lessen the ‘transplant shock’ they experience. Make sure you keep the plants watered so that the compost is just moist – avoid over watering as this can lead to diseases.  Gently brushing the tops of your transplants with your hand or a wooden stick will help control their height and increase stockiness. Ideal transplants are as wide as they are high. Gradually acclimatise the plants to outside conditions – a cold frame or greenhouse after being in the house, for example. Then give them a couple of hours in the outside each day (as long as it’s not too cold or windy) before they are fully ‘hardened off’.

7. Right potting – on time

Keep an eye on your new fledglings and occasionally look underneath the pots – when you see roots  emerging from the bottom it’s probably time to ‘pot them on’ into larger pots. This is broadly the same procedure as for ‘potting up’ and may mean that some plants are transplanted two or three times before they are finally placed in the garden. ‘Keep them moving’ and don’t allow them to become pot bound.

Further information:

Capel Manor College video on pricking out

Garden of Eaden video etc.

Old School Gardener

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