City Times Gardening

After a busy month of sowing many a herb, vegetable and ornamental, its now time to prick out seedlings. This involves teasing out the seedlings and transferring them to a new container.

Why Is Pricking Out Necessary?

If seedlings are left to grow on in crowded conditions, they become drawn, with small leaves and long spindly stems and will never grow into good quality, sturdy plants. Pricking out will give seedlings more light, space and air making them less prone to fungal diseases.

The seedlings are transferred from a seed sowing compost to potting compost, which contains a higher level of nutrients than seed compost.

Broadcast seedlings may germinate erratically, so a range of sizes can often be seen in the seed tray. They can be graded during pricking out so that growth is more even.

Seedlings are spaced out so that they grow at a uniform rate. This should mean that all the plants will be ready at the same time.

When Should Pricking Out Be Done?

Basically as soon as possible - usually when the cotyledons have fully expanded. The seedling should have leaves that are large enough to handle and a simple, single, short root that will not be damaged by transplanting. Another indicator is when seed leaves are touching.

Working Area

Pricking out should be undertaken either in a purpose-built clean pricking-off shed, or in the glasshouse beside the area where the containers of pricked out seedlings are stood down.

Gather all the necessary equipment and organise the workspace so it is both comfortable and efficient.

Equipment

Choose suitable low nutrient potting compost such as loam-less peat-free potting compost or J I No. 1 potting compost. Never reuse potting compost.

Containers to be used can range from seed trays to modular trays or individual pots depending on the seedling. Today, seed trays are less popular, modular trays are more common. Containers must be clean to prevent the spread of fungal disease.

A striking off board is used to remove excess compost. Boards that mark the pricking out stations are sometimes useful. They may be bought but may be made with two pieces of wood and nails spaced at regular intervals.

A dibber (a length of bamboo cane or a proprietary one) is used to tease out the seedlings.

Method

Prepare the Container

Fill the container with compost and strike off the excess. Modular trays should be tapped to settle the compost. If pricking out into a tray, an adapted striking off board may be used to mark out the planting stations.

Prepare the Seedlings

Water the seedlings well in advance to ensure the compost is moist when you come to prick out the seedlings. Ideally the seedlings should not be wet when you prick them out as this will make them more susceptible to damage.

Tap the tray of seedlings to loosen them from the sides. Loosen the compost with your dibber, and holding the seedling by the leaf gently tease it out of the compost. Make a hole in the compost using your dibber and insert the seedling into the hole. Gently firm the compost around the seedling.

Remember to never pick up a seedling by the stem as this will cause damage. Always pick up seedlings by the leaf using your thumb and forefinger. Do not delay inserting the seedling into the compost as they dry out very quickly.

Most seedlings are pricked out individually, but some small seedlings such as Lobularia maritima (Sea alyssum) and Lobelia erinus (Lobelia) are pricked out in small clumps of up to five seedlings.

Larger seedlings or high quality specimen plants may be potted-off directly in to individual 7cm pots.

Gently firm the compost around the seedling so that the seed leaves sit just above the compost - if the seedling is left very tall it will not produce a sturdy plant.

Water the seedlings in, place the container in suitable temperature to grow on and protect from strong sunlight. Check out this RHS link for further information www.rhs.org.uk/propagation/seed-indoors.

Lastly, for the first half of April, consider looking at the following tasks:

• Start to look at any water conservation projects for this year. Have you thought about using rain harvesting devices such as water butts? They can be a real godsend when it’s relatively dry. Check out this link for further information www.rhs.org.uk/ garden-jobs/water-collecting-storing-and-using.

• The large cabbage white butterfly emerges as a butterfly in April or May, mates, and lays 20-100 yellow eggs in clusters on the underside of brassica leaves. The eggs hatch within two weeks and the caterpillars feed on brassicas. They pupate in June in a crevice or woody stem. A second generation of the adult emerges in July and the second pupae stage overwinters. For me, a simple but very effective control is to use net covers/ frames over the crop from planting through to harvest.

Here are a few other tasks for the month of April www.rhs.org.uk/ advice/in-month/APRIL.

Happy gardening

For any gardening tips please contact Tom Cole, Horticultural Lecturer, Capel Manor College, Bullsmoor Lane, Enfield, Middlesex, EN1 4RR or by email tom.cole@capel.ac.uk.