Seed trays, modules and pots
21.08.2023 - 12:01 / theunconventionalgardener.com / Emma Doughty
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.
Pricking out
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
Seed trays, modules and pots
When plants are grown in the soil they can send out roots, make friends with fungi, and source their own nutrients from their surroundings. In gardens we help them do this by improving and feeding the soil, a topic I will be returning to in chapter four. But when they’re confined in containers plants have a limited volume of soil and therefore a limited amount of nutrients to tap into.
Soil isn’t one thing, it’s a collection of different things that come together to make the life-giving, plant-growing ‘dirt’ that we love. We have a tendency to poison it, cover it over and generally forget that it’s there, but good soil is the heart of a good garden and something we should pay a lot more attention to.
An ideal seed compost is able to retain water, whilst at the same time letting excess water drain away to provide an environment that is damp but not waterlogged. It allows penetration of plant roots and is able to anchor plants, but has space for air. Its texture is consistent, and it is free from pests, diseases and weeds that would compete with the seedlings. As we have seen, it doesn’t need to contain many nutrients if seedlings are going to be pricked out; seedlings growing in modules will either need enough nutrients in the compost to support them through their first weeks of life, or suitable supplementary feeding.
There is a big trend at the moment in recycling containers to use in the garden (we’ve already touched on it with recycled food containers used for raising seedlings). There is also a large range of containers you can buy – from cheap plastic pots right through to enormous designer urns. What you choose is as much down to your budget as it is to your tastes, but all containers need to hold a suitable volume of potting compost and retain water whilst allowing any excess to drain away. If you are recycling containers to use for food plants then be sure that they’re clean and that they weren’t used to store anything toxic in their previous life. And remember that not all plastics are UV stable – some degrade when they’re exposed to sunlight.
When a seed sends out its first shoot and it rises above the soil level, germination is over and seedling development has begun. This is a particularly vulnerable time for the plant – it is running out of stored resources and needs to start collecting its own food. In this period of rapid growth it is also particularly at risk from pests and diseases.
When I set about blogging The Peat-Free Diet it was an experiment, an journey into the unknown. My aim was to provide gardeners who want to garden without the use of peat with the information they need to do so, and the book evolved into a gardening primer that assumed peat was not on the menu. My love of science made more of an appearance than I had anticipated and there are plenty of big words to cope with, but it is my hope that they are presented in such a way that they are not hard to swallow.
Potting on
The Pantry contains information about some of the items that are useful for a peat-free gardener, and gardening terms you may come across on your peat-free travels.
One of the big differences between now and the time before gardeners relied so much on peat-based composts is the rise in container growing. An army of modern amateur gardeners has to put up with small gardens, and possibly with no soil at all. Growing plants in containers allows us to garden wherever we like, and even to grow plants that would not thrive in our soil. Some plants are grown in containers to keep them under control; others so that they can be moved indoors in winter to ensure their survival.
Buying plants
There are no diseases that particularly single out plants grown in containers, with the exception of damping off – the fungal disease that affects seedlings, which we met in Chapter 2. As long as plants are kept well-watered and suitably fed (i.e. not stressed) then container culture should be very healthy, particularly if your potting compost was a sterile mix.