London (change)

Essentials for growing under cover

A greenhouse or polytunnel allows you to grow a wider range of plants, and extends the growing season. Once the structure is in place you'll need to kit it out with a few essential items, listed below.


You’ll have more success raising seeds and cuttings by enclosing air around pots and trays, using a covered propagator. A heated propagator or mat will speed along germination and rooting. Prices start at under £5 for an unheated model and around £15 if heated.

Automatic vent arm

Available for most greenhouses, but not for polytunnels, automatic vent arms prevent the house overheating on sunny days. This is particularly useful in spring and autumn, when temperatures fluctuate widely during the day.


Staging or slatted benches raise plants off the ground, avoiding cooler air. Plus, most are designed at a convenient height for working. Slats increase air circulation, reducing fungal problems. Some models are also have shelves underneath, for extra storage. Prices from £30.

Cold frame

A cold frame is a useful halfway house between the protected environment of a greenhouse or polytunnel, and cooler conditions outside. It is used to harden off seedlings and young plants by opening the lid on warm days.

Water butt

Greenhouses are easily fitted with guttering for rainwater collection. Where possible, position it on the north side of the greenhouse, to stop it casting shade onto crops. Don’t use rain water on seedlings, as it contains fungal spores which can cause ‘damping off’.

Discuss this plant feature

Talkback: Essentials for growing under cover
Your comment will appear after a quick registration step