Seed Starting in the UK: Trays, Propagators & Growing Tips

Growing plants from seed is a rewarding way to fill a garden, windowsill or allotment. The basic setup need not be complicated: the right seeds, a suitable growing medium, a tray or pots, moisture and enough light can get you started.

Read the seed packet before choosing equipment

Different vegetables, herbs and flowers have different sowing seasons and germination conditions. Always start with the instructions on the packet. Some seeds are best started indoors while others are more successful sown directly outside. UK conditions vary by region, and frost dates are not the same everywhere.

Seed trays, modules and propagators explained

Seed trays are convenient for sowing several seeds in a shallow area. Module trays give individual seedlings room for roots and can make transplanting easier. A propagator typically adds a transparent cover to help retain moisture and warmth during germination. Covers should be ventilated as appropriate and removed or adjusted once seedlings emerge to reduce excessive condensation and overheating.

Some kits use capillary matting, which draws water from a reservoir towards the growing medium. This can help maintain moisture, but you should still monitor it: the aim is evenly moist compost, not permanently waterlogged roots.

Simple steps for starting seeds

1. Choose a clean tray or module and fill it with a suitable, lightly moistened seed-growing medium.
2. Sow at the depth and spacing recommended on the seed packet; tiny seeds may have different light requirements from larger ones.
3. Water gently to avoid washing seeds away and label each variety with its sowing date.
4. Place the tray where the recommended temperature and light conditions can be maintained.
5. Check moisture daily; avoid both drying out and saturated compost.
6. Once seedlings develop, increase light and ventilation as appropriate, then pot them on when ready.

Common problems to watch for

Seedlings that become long and weak may need more light. Mould or collapsing stems can be associated with excess moisture, poor ventilation or unsuitable conditions. If germination is poor, check seed age, sowing depth, temperature and whether the variety needs special treatment. Avoid moving tender plants outdoors until conditions suit them; gradually acclimatising indoor-grown seedlings can help.

What should a beginner buy first?

Start with seeds appropriate to the season, a manageable number of modules, a suitable growing medium and a waterproof label. A propagator or self-watering kit may be helpful if you need more consistent humidity or moisture, but it is not essential for every species. Compare tray sizes against the space you actually have.

Discover seeds, trays, watering equipment and other essentials in Selaa’s Home & Garden department. For choosing pruning equipment later in the season, see our secateurs buying guide.

Note: Follow the specific instructions supplied with your seeds, compost and propagation equipment, especially regarding temperature, ventilation and safe use.