A Guide To Pricking Out Seedlings

May is a time of year when most of us turn our attention to warmer-weather seedlings grown inside on our windowsills and prick them out to allow them to continue to grow in pots or a seed bed in a greenhouse or polytunnel or under cloches outdoors. Pricking out is an important part of growing your own plants for your garden and a technique that you need to master if you are to meet with success in your growing endeavours.

Why prick out seedlings?

Seeds that were sown and have germinated in seed trays need to be pricked out so that they can continue to develop a healthy root system and will not be stunted in their growth. Pricking out is an essential step if you are to grow plants that will survive everything that the summer can throw at them. Seed trays are simply not deep enough for plants to form the root systems they need. They will have to be moved and grown on in a pot or cellular seed tray with a depth of at least three inches. The exact size of container and growing medium required will depend on the plant and its individual requirements.

When to prick out seedlings:

It is easy to tell with most seedlings when you should prick them out. For most plants, you will need to prick out the seedlings when they develop their first true leaves. The true leaves are the second leaves to appear, after the cotyledon or seed leaves have appeared, which reflect the leaf shape of the mature plant. With some plants like courgettes and members of that family, however, the seedlings grow so fast that you may have to prick them out before the true leaves appear.

How to prick out seedlings:

When pricking out seedlings, you can use a specialist garden tool called a dibber. You do not have to buy a special tool though, as a rounded stick, a pencil or a small spoon can be used just as easily. Always take seedlings out one at a time, and before removing them from the seed tray make sure you have made a hole ready to accept each one. Gently lift by a leaf and not by the stem. A broken leaf can be mended while a broken stem cannot. Only prick out the healthiest seedlings and leave any that do not look like they are doing very well. Lift by a leaf and gently tease out the seedling, trying to retain as much root as possible. Rest the roots on your stick or dibber and move it slowly into its new hole. When seedlings are gently firmed into their new pots, water with a fine rose on a watering can.

After pricking out, remember to harden all your seedlings off before they make their way to their final growing positions.