Essentials for growing under cover | gardenersworld.com

Plant features

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.

Propagator

You’ll have more success raising your own seeds and cuttings if you can enclose a small volume of air around their pots and trays, using a covered propagator. An electric heated propagator or mat will increase the speed of germination and rooting. Prices start at under £5 for an unheated propagator and around £15 for a heated model.

Fitting an automatic greenhouse vent arm

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.

Benches

Also called staging, slatted benches are invaluable for raising plants off the ground, where it may be cool overnight. Most are designed at a convenient height for working, so you can avoid straining your back. Slats allow air to circulate through and between the plants, reducing fungal problems. some models are also available with 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, providing a convenient water source. 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 may cause them to collapse or ‘damp off’.

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