How to sow seeds indoors

How to sow seeds indoors

Sowing seeds of flowers and vegetables is easy. Find out how to sow seeds in pots indoors, in our guide.

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
To do
To do

Do To do in January

Do To do in February

Do To do in March

Do To do in April

Do not To do in May

Do not To do in June

Do not To do in July

Do not To do in August

Do not To do in September

Do not To do in October

Do not To do in November

Do not To do in December

Planting seeds – or sowing seed, to use the correct term – is a simple and inexpensive way of growing new flowers and vegetables for your garden. Sowing seed indoors allows you to start the growing year much earlier than if sowing seeds outside. When growing salad and vegetable crops, it’s a good idea to sow a small amount of seed every two weeks, to ensure you have a long season of fresh produce to eat throughout summer. This is called ‘successional sowing’.

You don’t need a lot of kit to sow seeds. Many gardeners buy expensive propagators but a seed tray or a few plastic pots, will do the job. If you don’t have plastic pots then try using old yoghurt pots with holes punched in the bottom, or tomato or mushroom punnets instead of a seed tray. Any vessel that can hold compost and allow water to drain freely is suitable.

Buy peat-free, multi-purpose, compost. Some very small seeds need specialist ‘seed compost’ to germinate, but multi-purpose compost is fine for most seeds.

To maintain an even temperature and keep the soil moist, it’s a good idea to cover the soil with a clear piece of plastic. A bespoke propagator will come with its own clear plastic lid, but you can use cling film, old freezer bags or any clear plastic bag. Use cellotape or an elastic band to fix it to the pot.

More on sowing seed:

Video: Essential kit for seed sowing

Expert advice from Alan Titchmarsh

Follow our step-by-step guide to sowing seed indoors, below.

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You Will Need

  • Seeds
  • Multi-purpose, peat-free compost
  • Seed trays or pots
  • Plant labels
  • Pencil or waterproof pen
  • Watering can with rose attachment
  • Polythene bag
  • Sheet of glass, or a propagator

Step 1

Fill small pots or seed trays with compost. Use a watering can fitted with a fine rose to thoroughly wet the compost, and leave to drain.

How to sow seeds indoors - watering the compost
How to sow seeds indoors – watering the compost

Step 2

Sprinkle seeds evenly and thinly over the surface of the compost, leaving approx 2cm – 3cm between each one, if possible. Some seed is very small, making this impossible. Cover seeds with a thin layer of compost, about the same depth as the size of the seed (the smaller the seed, the thinner the layer of compost).

How to sow seeds indoors - sowing the seed
How to sow seeds indoors – sowing the seed

Step 3

Cover the pot with a clear polythene bag or piece of glass or clear plastic, to maintain an even temperature for germination, and keep the compost moist. Place the pot of seeds on a well-lit windowsill or in a heated propagator.

How to sow seeds indoors - covering the pots with a plastic bag
How to sow seeds indoors – covering the pots with a plastic bag

Step 4

Remove the plastic or glass cover as soon as the seeds have germinated and you can see the seedlings growing out of the compost. Grow them on in a warm place indoors – if growing them on a windowsill you may need to move them at night as temperatures can drop dramatically. The young plants will ready to be ‘pricked’ out when the second pair of leaves, known as ‘true’ leaves, emerges.

How to sow seeds indoors - seedlings growing in pots
How to sow seeds indoors – seedlings growing in pots

Step 5

When pricking out seedlings, handle them only by their leaves, not the stem. Fill a seed tray with compost and plant seedlings about 5cm apart, burying the seedling up to the base of the first set of leaves.

How to sow seeds indoors - pricking out seedlings
How to sow seeds indoors – pricking out seedlings

Step 6

After a couple of weeks, the young plants will be large enough to pot individually into 7.5cm pots, or planted outside in well-prepared soil. Handle plants gently, firm compost around them and water well. Don’t allow the soil or compost to dry out.

How to sow seeds indoors - transplanting young vegetable plants
How to sow seeds indoors – transplanting young vegetable plants
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