For straightforward seed sowing, Westland Peat-Free John Innes Seed Sowing Compost is a useful starting point. Choose Dalefoot Wool Compost for Seeds when moisture retention is a priority, or Miracle-Gro Peat-Free Seeds, Plugs & Young Plants if you want one bag for sowing and the first stages of growing on.
The important differences are texture, moisture behaviour and the stage of growth the mix is intended for. Small seeds need close contact with an even surface; young roots also need air.
What a seed compost needs to do
A fine, reasonably uniform texture makes it easier to sow evenly and cover small seeds to the right depth. Break up lumps before filling the tray and remove large pieces that would leave a seed suspended in a gap.
Seedlings need a suitable balance of moisture and air. Firm the compost gently so it supports the seed, then water carefully and let the excess drain. Pressing hard can make a shallow tray dense and slow to dry.
Look for a formulation intended for sowing or young plants. A rich mature-plant compost, manure-based improver or double-strength feed mix has a different job. Peat-free products vary considerably, so learn how the particular bag feels when properly watered.
Best straightforward seed mix: Westland Peat-Free John Innes Seed Sowing
This is a practical choice for gardeners wanting a dedicated seed compost in a manageable bag. Choose the Seed Sowing formulation, rather than John Innes No.3 or a multipurpose compost with added John Innes.
Westland’s loam-based seed mix gives a settled surface for sowing and is designed for the early stage of growth. It suits the familiar routine of sowing into trays, then moving seedlings into individual pots once they are ready to handle.
Fill and settle the compost evenly before sowing. Use the seed packet for depth: a fine compost does not mean every seed should receive the same covering. For tiny surface-sown seed, water the tray beforehand so a heavy watering afterwards does not bury it.
The linked option is the peat-free 10-litre seed-sowing bag. Compare larger packs only if you will use the extra compost and can store the remainder dry.
View Westland Peat-Free John Innes Seed Sowing Compost on Amazon
Best when trays dry quickly: Dalefoot Wool Compost for Seeds
Dalefoot’s seed compost is worth considering on a warm windowsill where small trays lose moisture quickly. Its wool-based formulation holds moisture, while the seed version has a finer texture than the richer mixes used for established plants.
The range uses wool, bracken and comfrey. Choose the bag marked for seeds or seeds and propagation; Dalefoot’s Double Strength compost is a different product and is unsuitable for sowing small seedlings directly.
Check moisture by touch and by lifting the tray. You may need to water less often than with your previous compost, so avoid keeping the old daily watering routine automatically. A moist tray does not need another soak just because the surface has changed colour.
The 12-litre bag is a useful size for a modest sowing programme. When comparing delivered cost, include the number of bags and other items in the order rather than judging by the headline bag price alone.
Best for sowing and early potting on: Miracle-Gro Seeds, Plugs & Young Plants
This formulation is convenient if you want one bag for sowing, pricking out and potting small plugs. It has a feed supply intended for young plants, avoiding the need to move immediately from a seed-only purchase to a separate bag for the next stage.
It is a different product from Miracle-Gro’s Premium All Purpose compost. Read the name carefully when ordering: the Seeds, Plugs & Young Plants version is the one linked here.
Use it for the early stages described on the bag, and follow the feeding instructions once that initial supply is used. Seedlings growing slowly in cool conditions will not need the same watering and feeding routine as vigorous young plants in warm, bright conditions.
A 20-litre bag makes sense if you have several trays and pots to fill. If you sow only a few small pots, a smaller dedicated seed mix may be easier to store and use while fresh.
View Miracle-Gro Peat-Free Seeds, Plugs & Young Plants compost on Amazon
Can you use multipurpose compost for seeds?
A suitable peat-free multipurpose compost can work for many larger seeds. Sieve or pick out coarse pieces where needed, and check that the bag is suitable for sowing. A dedicated seed mix is easier to work with for tiny seeds or a small, valuable batch where you want a consistent surface.
Sifting changes texture; it does not remove fertiliser or turn a rich potting mix into a low-nutrient seed formulation.
For outdoor winter containers and established shrubs, you need a different comparison. The winter pot compost guide covers seasonal bedding, mature shrubs and acid-loving plants.
Water the compost underneath the surface
Moisten dry compost evenly before sowing, then let the tray drain. After sowing, use a fine rose or brief bottom watering so seeds stay where you placed them.
Check below the top layer before watering again. The surface of peat-free compost can dry while the root zone remains moist. A tray that still feels heavy and damp underneath may need more air and time rather than another watering.
Keep covers ventilated as seedlings emerge and give them good light. The propagator guide explains when warmth helps, while the seedling lighting guide covers weak indoor light.
Use clean pots and trays, close the compost bag after use and store it somewhere cool and dry. If a bag is badly waterlogged or contaminated, use fresh material for a valuable sowing rather than trying to compensate with extra heat.
For the complete setup, see starting seeds indoors. Growing references: Dalefoot’s seed compost guidance and RHS indoor sowing.
