Plant Protection Reviews 2026

A glass or polycarbonate greenhouse holds heat and light well and lasts a long time, but costs more per square metre. A polytunnel gives far more growing space for the money, though the cover typically needs replacing every five to ten years.

Simply keeping it frost-free, around 3 to 5C, is enough to overwinter most hardy and half-hardy plants. Tender plants need around 10C or more. Heating only a partitioned section is far cheaper than heating the whole structure.

Lighter fleece of around 17 to 30gsm gives a couple of degrees of frost protection while letting plenty of light through. Heavier 30 to 50gsm and above protects against harder frost but cuts light, so it suits short cold spells rather than permanent cover.

Horticultural bubble insulation noticeably reduces heat loss and cuts heating costs, but it also reduces the light reaching your plants. Most growers fit it for the winter months and take it down again in spring.

A heated propagator provides bottom heat for germinating seeds, usually indoors or in a greenhouse. A cold frame is unheated and is used for hardening off young plants before planting out, and for overwintering hardier stock.