A burgeoning batch of seedlings is a thing of beauty, but it’s also a responsibility – each tiny plant is dependent on us for everything it needs. It grows rapidly, needing more space, water, light and nutrients. Although we lavish care on them in their early stages, each plant needs to be prepared for the challenges of the outside world. Allowing your seedlings to grow up is the key to growing them on.
If you’ve sown your seeds in a tray then as soon as they have unfurled their seed leaves you know that they are growing roots and are going to need more space. Pricking out is the process whereby each healthy seedling is transferred to a more spacious home – whether it’s another seed tray with fewer companions or a pot of its own. Pricking out can be quite daunting, as each tiny seedling is fragile and needs to be handled with care. It’s a slow and painstaking process, which is why many people prefer to sow in modules.
The good news is that you only need one piece of equipment for pricking out – a teaspoon, or the end of an old pencil or pen. Get the next tray, or the pots, ready with supplies of compost – something with some nutrients is what you need, although nothing too strong. If you’re not making your own mixes then multipurpose compost is fine, although you may still want to sieve out any large lumps. Gently settle the compost in the pots as before.
Select the seedling you’re going to prick out. Gently take hold of one of the seed leaves (some plants only have one!). Using your chosen implement, gently lever it out of the soil. Roots are a bit like icebergs – they spread much further under the soil than it would appear from the top parts of the plant. What you’re trying to do is loosen the soil under the seedling so that you can lift (don’t pull!) it out from the soil in one piece. Then transport it over to its new home, use the same implement to make a small hole in the new compost and slide the seedling in to the same depth it was at before. Using your fingers, gently firm the compost around it so that it stands up by itself (it may not end up straight, but don’t worry – it will work that out for itself once it starts to grow).
Using a watering can with a fine rose, or some other gentle means, water the seedling in. This makes the compost nice and moist but also settles it back around the roots and means the seedling can establish itself more quickly.
Pricking out is best done as soon as the seedlings are large enough for you to handle. Seedlings cope with it better when they’re very young, and it’s also easier because their roots won’t be long enough to tangle together.
As I said before, don’t hold them by the stem – if you snap it, that seedling is dead and will have to be discarded. If more seeds have germinated than you expected, don’t feel you have to prick them all out. If they’re edible, eat the excess as sprouts. If they’re not, you could offer them to friends and neighbours. Or you can put them on the compost heap. It’s far better to do that than waste your time looking after acres of seedlings that you won’t be able to plant out later; keeping a few spares as a safety net is a good idea, though.
If you have sown your seeds into larger containers and used a compost with some nutrients to do so then they will be fine in their home for a while longer – but you do need to ensure they are not overcrowded.
Again, it’s a case of being cruel to be kind and of ‘thinning out‘ – removing seedlings that are surplus to requirements. You can pull them out and then water the compost to settle the remaining seedlings, but an easier option is often to simply snip through the stems of the ones you don’t want to keep. Leave the biggest, strongest seedlings in place and cull any that look a bit pathetic, or are growing too close together.
Thinning out is done outdoors, too. When sowing seeds directly onto the ground it’s usually wise to sow more thickly than you would indoors, as fewer seeds may germinate and then survive to the seedling stage – it’s an insurance policy to ensure you get enough seedlings, but then you have to remove the surplus. You can thin in stages, removing seedlings in batches as they grow and need more space.
If you want to practice pricking out or thinning out then buy yourself a packet of cress seeds – they’re very cheap and you get a lot in the packet. You can sprout them in a thin layer of compost or even on damp kitchen paper (although you have to keep it damp, they wilt very quickly when it dries out). It only takes a few days for them to be large enough to practice on, and you can use your thinnings in sandwiches when you’re done. You’ll be a dab hand at handling seedlings in no time, long before you reach the bottom of the seed packet, so find some kids and grow egglings (cress sown in eggshells with faces painted on them) with the rest!