Tips for Success (Spring 3)

Seed Trays

No need to spend money on large seed trays for seed sowing. You can make your own from wooden slatted veg boxes lined (base and up the sides) with a double layer of plastic bin liner. No need to be tidy, it just has to fit. Greengrocers and restaurants often throw out these wooden boxes.
Remember to pierce the bin liner base so water drains.
Remember to position the trays on a waterproof surface. And don’t overwater!
Don’t be scared of tiny seedlings! Consult Pricking out and Potting…

Pricking Out and Potting

Once seeds have germinated, in their trays or small pots, they are usually transplanted into larger pots. They can be pricked out (transplanted) individually, if they are going to develop into large plants (such as Pelargonium, Gazania, Tomato). If they are small plants (such as Lobelia and Busy Lizzie), they can be pricked out in small batches.
These will then develop into good clumps that will make an impact wherever they are finally planted.
Potting on – some plants need to be transplanted more than once. These are usually the larger plants (Pelargonium, Gazania, Tomato, Peppers, Aubergine). As they have quite a long growing time inside, they will run out of space in a small pot. It is usual to pot on (transplant) twice. The final pot used (15cm or 20cm) is large enough to allow the plant to develop an extensive root system before being planted outside.

Equipment needed

  • Fresh potting compost
  • Horticultural grit – (medium)
  • Range of pots, trays, module trays – well-scrubbed if necessary
  • Blunt pencils/thin plant sticks/old forks


Step one: Seedlings prefer good drainage. Mixing grit and potting compost together guarantees seedlings won’t sit in soggy, packed compost.
Mix grit thoroughly with potting compost – parts by volume: 1part grit to 2 parts potting compost. This will provide a good mix for seedling development. The easiest way to make the mix is to use a small bucket, or large bowl as the measuring container. Put a large plastic sheet on the floor, and tip the potting compost and the grit onto it. Now you can easily mix the two materials together, using either hands or small garden tools.

Step two: Fill the empty trays and pots with your compost/grit mix. Shake and tap containers to settle it down well. Firm gently – it should be neither too open or loose, nor packed solid.
Stand the newly filled containers in a dish/sink of slightly warm water for about five minutes. Seedlings need to go into a moist environment. Remove from the water and allow to drain well until drips have more or less ceased.

Step three: Using your implements, make some holes in the settled compost/grit mix, ready to receive the seedlings. Holes should be deep enough to take the plants’ roots. Lift one little seedling out to see what you need to aim for.
Seedlings of large plants can be pricked out singly, if you have small pots. Or you can put two or three into a larger size pot, and pot on again once the seedlings have developed.
Small plants, where single plants make little impact, can be grouped together in fours, fives or sixes. They will develop happily together. When planted out finally, they will bush up nicely.

Step four: Now you’re ready!
Gently insert your implements under the seedlings – try to get right under the roots. Lift out a clump, including the compost, and put it onto your work surface. Now – using your fingers and only holding the seedling’s leaves, gently pull the tiny plants apart. If you’re planting in clumps, the Lobelia for example, there is no need to separate each plant. Just hold a small number of plants together, and insert into the new pot. Always hold the leaves, never the stems.

Make a suitable sized hole to take the seedling(s), and re-plant in the new pot.

Firm seedling(s) in gently, no ramming! This is the time when you discover if the potting compost is too loose. If it is, the seedling(s) will have too much air round the roots. Just firm everything down gently, and carry on. Label your pots/trays and place in a light, warm place for the seedlings to settle in. Install your reflective backings once more. Sunny windowsills can be a bit too bright for seedlings. Spring sunshine can scorch baby leaves. Tables out of direct sunlight are better than windowsills in full sun.