COVID Update
Due to unprecedented high demand we have suspended accepting orders for plants to be sent out on a UK wide basis whilst we catch up.  Orders to local areas which use our own delivery vans are unaffected.  We apologise for any inconvenience this may cause. 

01308 422654

How to Sow Seeds Indoors & Out



Growing from seed is a simple and economical way of raising new ornamental and edible plants for your garden. It’s something you can give just a few hours to as a novice ‘grow your own’ fan or spend all your days on and become self-sufficient. It is also a great way to introduce children to gardening, giving them a few very easy quick growing plants like sunflowers or radishes and a little patch of their own can start a lifelong passion for gardening.

Sowing your own seeds is a bit like learning to wallpaper, follow the general principles but with experience develop your own methods and shortcuts. Once you start you’ll find it simple and so rewarding but always follow the instructions on the packet as some seeds will only germinate in darkness, some prefer light and some aren't fussy either way!

     flowers     child

Indoors or Out?

Sowing indoors allows you to lengthen the season and if you don’t have a heated greenhouse, a propagator or sunny window sill will work very well. As you will have to harden the seedlings off before transplanting into your garden plants that transplant well are the best candidates for vegetable seed sowing indoors. These include leeks, beans, tomatoes, cauliflowers, courgettes and peppers. Less keen on being transplanted are carrots, beetroot, parsnips, radish, swede and turnips. Starting like this is ideal for areas of the country that have a shorter growing season.

Growing outdoors is easier for those with limited space for trays and propagators indoors. Many vegetables such as beans, carrots, peas and parsnips plus annuals, biennials and herbaceous plants can be grown from seed sown outdoors. The secret to success is to prepare a good seedbed, free of weeds and with a crumble-like soil-surface texture.


Sowing Indoors

Sowing indoors allows you to raise plants from seed in early spring - much earlier than if sowing directly outside. This method also enables you to have plants ready to fill empty spaces as they arise. Vegetables like runner beans, tomatoes and peas can be started indoors rather than directly outside and bedding plants like marigolds (Calendula), morning glory (Ipomoea) and sweet peas (Lathyrus odorata).Also when you’re growing salad crops, it's a good idea to sow seed successionally every two weeks, to ensure you have a long season of fresh leaves to eat throughout summer. Perennials like Alliums, Penstemon, Salvia and Pinks can also be grown but take a year or two to get to full size.

You will need

Fill small pots or seed trays with seed compost. Use a watering can with a fine rose to moisten the compost. Leave pots to drain.

Sprinkle seeds evenly and thinly over the surface of the compost, leaving approx 2cm - 3cm between each one. Cover seeds with a thin layer of compost.

Cover pot with a clear polythene bag or piece of glass, to preserve compost moisture. Place the pot on a well-lit windowsill or in a heated propagator. 

Remove cover as soon as seedlings emerge and grow on in a warm place indoors. They will ready to be 'pricked' out when the second pair of leaves, known as 'true' leaves, emerge. The first pair of leaves look different to those that come after. This first pair are the seed leaves that provide the seed with but have the ability to photosynthesise too. So when your seed packet refers to ‘true’ leaves it means those that appear after the seed leaves have unfurled.

When pricking out seedlings, handle them only by their leaves, not the stem. Fill a seed tray with seed compost and plant seedlings about 5cm apart, burying the root up to the base of the first leaves. Your seedlings are very fragile so handle with care to avoid damaging and water underneath using a very fine hose so you don’t deluge them. Some people spray them gently using an old ( well cleaned) kitchen or bathroom cleaner bottle.

After a couple of weeks, the young plants will be large enough to pot individually into 7.5cm pots, or planted outside in the well-prepared soil. Handle gently by unearthing them with a dibber, pencil or plastic seed label to loosen the roots and hold onto a seed leaf, not the stem as squashing that will check the growth later in its development. Then firm the compost around them and water well and don’t allow the soil or compost to dry out.

As stated previously you need to harden off your young plants before planting them in their final home when all chance of frosts has passed. To harden off you basically introduce the plant to the colder outside world over a 2 or 3 week period. Techniques depend on the facilities available. Plants raised in a heated glasshouse or on windowsills ideally should be moved into a cold glasshouse for two weeks, then into a well-ventilated cold frame for a final week. If you do not have a glasshouse, move plants into a cold frame. Open it a little during the day and close it at night, increasing ventilation gradually over time and remove the cover a few days before planting. Cover cold frames with carpet or hessian if a late frost is forecast. If you do not have a cold frame, place plants at the base of a sheltered, south facing wall or hedge, or somewhere sheltered during the day, protected for the first few days a couple of layers of fleece. Bring plants indoors at night, in the first week, and use a single layer of fleece for the first part of week two. After about 10 days, depending on the weather, remove the fleece during the day and leave plants outdoors at night if it’s mild. Leave them uncovered towards the end of the third week, before finally planting out.

Sowing Outdoors

You can start a bit later than sowing indoors and you would usually scatter ornamentals in drifts to achieve a natural look and your vegetables and cut flowers in clear lines so that thinning out and weeding is easier. Always refer to the seed packet though as the instructions will be clear for the chosen plants.

When to Plant

As long as the soil is warm and moist, seed can be sown and it will germinate quickly. In practice, this usually means either mid-spring to early summer (April-June) or late summer (September). If you can provide the crop with protection, such as cloches or fleece, sowing can begin in early spring. Likewise, regular watering will make it possible to raise rows of seedlings in the height of summer.


Sowing seed is very straightforward – you only have to think of how many plants scatter their seeds and they grow where they land as soon as it is moist and warm. However, for the best success, this is the best way to sow:

  • Beds should be dug in advance to allow time for the soil to settle. A spades depth is enough.
  • Cover over the roughly dug bed with plastic or a double layer of fleece to suppress weeds and, in early spring, to help warm up the soil.
  • When you are ready to sow, uncover the bed. Use a rake to level the surface and create a crumble-like tilth. Then pick off any remaining weeds, leaves twigs or other debris.
  • Place a cane or stake across the bed and lightly push it into the surface. This will create a straight drill (shallow depression) whose depth should be as directed on the seed packet and repeat the process with the drills spaced according to the instructions on the seed packet.
  • Add water to the row before sowing.  This is usually better than watering over the top of sown seeds.
  • Thinly scatter the seed into the bottom of the drill. Don’t be over enthusiastic, as plants will need thinning to the spacing recommended on the seed packet. A finger width apart is usually right for small seeds.
  • Use a rake to gently cover the seeds with soil, filling the drill back in again.
  • Before you forget where the row is and what you’ve sown, place a label in the soil at one end.
  • Cover the patch with a single layer of fleece. Use a spade to push the edges of the fleece into the ground to ensure it doesn’t blow away.
  • Remember to water gently in dry spells.
  • When the seedlings emerge thin as per seed packet instructions.

transplant   agriculture

Common problems

Rain can compact the soil sometimes stopping seeds emerging so a sprinkling of peat-free multipurpose compost sprinkled over the seeds can help avoid this

Pigeons and mice may try to eat your seeds particularly larger ones like peas so covering with fleece helps.

Damping off can occur when seedlings keel over in wet weather but is more likely to happen with seeds grown under glass indoors.

Slugs and snails can also be a problem so look out for them and take preventative action.

dove     slugs

Posted by Charlie Groves

Charlie is the manager at Groves Nurseries.  He is the 6th generation of C.W. Groves to run the garden centre. 

Products related to this article

Stewart Heated Propagator 52cm

Stewart Heated Propagator 52cm

This electric heated propagator provides the ideal environment for seedlings and cuttings ..

£29.99 Ex Tax: £29.99

Plantpak Propagator Lid

Plantpak Propagator Lid

This Standard Seed Tray Lid will help to give your plants a helping hand by ensuring they ..

£1.99 Ex Tax: £1.99

Related Articles

Sowing Violet Seed

Violet seeds are quite difficult to germinate, so we have put together this hand guide to help you.

February in the Garden
With the odd bits of sun shining through you'll have the chance to spend an hour or so back in the g..
March In the Garden

March in the Garden

The product is currently Out-of-Stock. Enter your email address below and we will notify you as soon as the product is available.