Classroom Activities (Spring 1)

Sow seeds of plants that require a long growing period in order to flower/crop this coming summer.

Equipment needed

  • Potting compost – organic if possible. At least try for peat-free (see Tips for Success)  You’ll need a 60L or 80L sack to start with. More potting compost will be required later as the plants grow and need to be transplanted.
  • Seed trays or pots with wide tops (not small yoghurt pots)
  • Trays to stand pots in (see Tips for Success)
  • Seeds
  • Silver sand (small bag)  (see Tips for Success)
  • Plant labels (see Tips for Success)
  • Square dish/bowl large enough to stand seed trays in when watering. Any large plastic boxes or bowls can be used for this purpose. They just need to hold about 1cm of water.
  • Clean water at room temperature. Store clean tap water in empty water/cleaned squash bottles so that you always have a supply at the correct temperature.
  • Clear plastic bags to cover the pots and trays. They can be used bags, but MUST be clear and have NO HOLES. They can be re-used frequently, but always wash before re-use.


  1. Bring potting compost inside in good time to warm up. Lean bag of compost against a radiator so it can warm through. Turn the bag so that both sides spend time against the warm surface. This will take a couple of days.
  2. Make sure that pots/trays to be used are clean. If necessary, scrub with hot soapy water, then rinse well.
  3. All pots/trays should have drainage holes in the bottom. If using recycled pots without holes, use a knife or screwdriver to pierce the bottoms.
    Waterproof trays can be made from cardboard boxes, cut down to a suitable size, then lined with a plastic bin liner, also cut to size. They only need to be 6 or 7cm deep.


  1. Fill the pots/trays you have cleaned, to within 1.5cm of the brim with potting compost.
  2. walled-gardenShake gently, and tap the pot on a hard surface, to ‘settle’ the compost into all the corners of the container.
  3. Firm the compost very gently. Use the back of your knuckles for this, or the underside of a small pot that fits into your container. Take care – it should be just firm, not rammed down like concrete.
  4. Sow the seeds thinly over the potting compost.
  5. Cover seeds, if appropriate, with a light covering of potting compost. Fine seeds should not be covered. They are too small to germinate successfully if covered up. Seed packet instructions will tell you which are which.
  6. Stand containers in a sink, or a dish of just warm water for no longer than 3 minutes. The water will be sucked up through the holes in the bottom of the pots.
  7. Remove the pots from the water and allow excess water to drain.
  8. Once drained, place pots in their trays, and stand in a warm light place. Full sunlight is not ideal. A table near a window will be fine. At this stage, warmth is more important.
  9. Cover with a clear plastic bag to retain humidity. Close the bag with a peg or string, to create a mini-greenhouse. This bag should be removed daily for around 5 minutes, and turned inside out before being replaced. Once seeds germinate, the plastic bag is no longer required. Label each pot/tray.

Seeds for Inside Sowing


geraniums Summer Flowering Geraniums (Pelargoniums) – they require a long growing season if they are to flower in the summer. Use in hanging baskets, ornamental pots and containers outside. These are tender plants, and need to be sown inside, as they require warmth for germination. They should not be planted out until late May or early June.
 lobella Lobelia – beautiful trailing plants used in hanging baskets and containers outside. Again, tender plants, needing warmth and care. Sow thinly using silver sand method. Do not cover seed.
 onions Onions – always useful in the kitchen! Sow 6 seeds together (multi-sowing) in a small (7cm) pot. Or you could use a large yoghurt pot for these. Let them germinate and develop in the pot, and they’ll be ready for sale in February. They can be planted out in the garden once the soil warms up, just as they come from the pot. The onions won’t be big, but they will be tasty!
sweet_peas Sweet Peas – a perfect present for Valentine’s Day!  What could be nicer than a pot of sweet pea seedlings, ready to plant in the garden this spring? They’ll start to flower in early summer, and last for months as long as you pick off the dead flowers. And if you save some seeds in the summer, you’ll be able to sow them again next year.