Planting a seed

If you want lots of plants – say, petunias for window boxes – starting from seed is cheaper than buying ready-grown plants. The choice of colours and varieties is larger, too. As well as annual bedding plants, seedsmen offer packets of mixed seeds of cacti, ferns, palms, Cyclamen, African Violets and even orchids.


A seed contains a tiny, immature, or embryonic, plant. If conditions are right, the seed sprouts, or germinates, and a new plant grows. It will look like its parents, sometimes with minor variations, rather like the children in a large family. All annuals, and some perennials, are easily grown from seed. Bulbs and woody plants are usually propagated in other ways.

Types of seed

Seeds con be as small as grains of sand or as big as a coconut, and have a hard or soft coat. Seeds are often round, but can be flat, winged, clustered or hooked, depending on whether they are spread by wind, animals or even water in the wild.

Most seeds are sold in air-tight, waterproof, heat- and cold-resistant sealed packets, to keep them fresh. Always check the ‘Use by’ dates on seed packets before buying, and plant the seeds as soon as you open the packet.

With specially prepared seeds, you don’t need to thin out seedlings, but only seeds of very popular plants are treated, and they are expensive. Pelleted seeds are coated to make them larger and easy to plant. Seed strips are tapes with seeds stuck down at the correct spacing, and you just bury a strip in the potting mixture. Some seeds are sold in containers of soil-less potting mixture, ready to sprout as soon as you add water. Follow manufacturers’ instructions with prepared seeds.

The range of seed size shape and colours is huge but all serve the same purpose – to prolong the species.

Preparing and sowing seeds


February or March is usually the best time, but check the packet first. Use clean, dry seed trays or 8cm (3 inches) pots, peat-based potting mixture for cuttings or seedlings, labels, and transparent polythene bags or sheets. For plants such as Sweet Pea, which resent root disturbance, use compressed peat pots. With these pots,you just plant or pot up the seedling, pot and all, when the plants are ready to be planted out.

Fill the container with potting mixture, and evenly firm it to within 13mm (1/2 inches) of the rim. Scatter or place the seeds thinly and evenly over the surface. (Check the packet for ideal spacings.) Mix tiny seeds with sand first, to help spread them. Tap medium-sized seeds out of a cut-off corner of the packet, using your index finger. (Do a ‘trial run’ first by tapping them into your hand, until you get the pressure right.) Large seeds, such as the seeds of Sweet Peas or Nasturtiums, can be placed exactly where you want them.

Finishing the job

Cover the seeds with a thin layer of sieved potting mixture, roughly as deep as the seeds are thick. Cover very fine seeds with a dusting of silver sand.

Some seeds should not be covered, so check the packet. Water by standing the pots or trays in a water-filled sink or bowl, to come half-way up the sides of the container. When the potting mixture turns dark brown, watering is completed.

Label, then cover the trays with polythene or a sheet of glass, and then a sheet of newspaper to help prevent condensation and overheating. Place pots in see-through polythene bags, pierced with a few ventilation holes, and fix the polythene bags securely in place with an elastic band.


Overview of planting seeds

  1. Fill a tray with potting mixture. Firm to within 13mm (1/t inches) of the rim, using a flat piece of wood with a handle attached (easily made at home).
  2. Thinly and evenly scatter or place seeds on the surface. Check the seed packet for spacings. Mix fine seed with sand first.
  3. Cover the seeds with a layer of sieved potting mixture, as deep as the thickness of the seeds. Check packets for exceptions.
  4. To water, stand the tray in a sink and let the water come half way up the sides. Remove when the potting mixture turns darker.
  5. After watering, cover with glass or polythene and a sheet of newspaper to help reduce condensation and overheating.

After care

Keep lightly shaded at a temperature of 18°-24°C (65°-75°F) – an airing cupboard or north- or east-facing window sill is ideal. Every day, wipe off water that collects on the glass or polythene. As soon as the seedlings appear, remove the cover and place the seedlings in a lighter spot. Water regularly, using a mist spray. If the seedlings are crowded, thin them as soon as they are large enough to handle. Gently pull out and discard unwanted seedlings, so the rest are 13mm (1/2 inches) apart. Firm the mixture around the remaining seedlings, then water.

When the second set of leaves, or ‘true leaves’, appear, prick out the seedlings. Prepare trays or pots as above, with a low-nutrient potting mixture, such as John Innes No 1. Using a pencil, make planting holes 2.5cm (1 inch) apart each way. With the pointed end of a plant label, ease the seedlings out, and, holding them by the leaves, lower each one into a prepared hole. Firm and water lightly, then keep shaded for a few days.

If the plants are for your balcony or patio, start hardening them off in late spring. Place them in a sunny, sheltered corner, and bring them in at night or when frost threatens.

As soon as the seedlings are large enough, prick them out and re-plant at least 2.5cm (1 inch) apart.


Why does my friend take a little nick out of sweet pea see s and soak them before planting?

This lets moisture through the hard seed coat, so the seeds swell and sprout quickly.

What is an F1 hybrid?

This is a plant produced by crossing two pure-bred strains under special conditions. Fl hybrids are usually stronger and more uniform than ordinary plants, but more expensive, as the crosses have to be made fresh each year.

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