Growing under glass: fit your garden & budget
Growing under glass is incredibly rewarding, expanding the range of plants you can try.
Unfortunately, investing in any structure – whether it be a greenhouse, conservatory, cold frame, polytunnel, mini-greenhouse, grow house or fold-up tomato house – can be fraught with difficulties.
If you need inspiration and want to assess what you can afford, there’s a huge selection of greenhouses, polytunnels, cold frames, mini-greenhouses, grow houses or tomato houses available at Primrose.
First, there are costs to consider. Budget options are usually that for a reason – lightweight push-together frameworks covered with PVC ‘tents’ are commonly called ‘blow-aways’ – not great for windy or exposed sites like mine.
I had a bad experience with an 8’x4′ grow house, which retailed at nearly £100 and was wrecked after three days.
In May 2015, I invested in an 8’x4′ lean-to aluminium greenhouse, with double doors down the long side, which is great – but I’d recommend getting a professional to install one. It was utterly beyond me and the other half, so I hired a builder to do it.
He managed to overcome a slope, a back wall that’s way out of line and the lean-to was a few centimetres too tall after the ground had been levelled – all in a day.
Pay the extra and invest in toughened glass, for safety’s sake. Storm Desmond wreaked havoc with my greenhouse – five of the large panels blew out, although only one smashed (but that cost £62 to replace).
My conservatory has been great, but from March to October, you can barely enter the house without knocking something down. The colder months aren’t much better, with half-hardy perennials to overwinter.
It’s also up a flight of stairs, meaning many heavy pots have to carried outside/back inside in spring and autumn.
Potted guide: undercover gardening
The pros and cons of undercover structures:
Can be constructed to your specifications.
Can be successfully heated.
Toughened safety glass can be installed – but more expensive.
CONS: Expensive, especially wooden framed models.
Base needed for stability.
Difficult to build.
Requires time and effort to clean.
Wooden frames require treatment to prevent rot.
A danger of cheaper horticultural glass shattering.
PROS: Prices get more reasonable as size increases. No glass to break.
Large areas can be covered.
Storm resistant if installed properly.
Professional growers’ choice.
CONS: Not cost-effective on a small scale.
Manufacturers rely on you putting them up – I was quoted £700 to install a £400 model.
Cheaper covers need replacing.
Not as aesthetically pleasing as a greenhouse.
PROS: Great habitat for exotics.
Sit and enjoy your plants.
Part of the house, so no cold journeys outside.
Temperature can be controlled.
CONS: If used as a sitting room, etc, not practical to have soil everywhere.
Using it as a greenhouse may upset family members. Really expensive.
Temperatures rise and fall dramatically if ventilation is not monitored.
PROS: Cheaper but sizeable alternative to greenhouse or polytunnel.
Easier to install.
CONS: Avoid if you live in a windy area.
PVC covers rip at seams easily.
Light intensity poor.
PROS: Strength of those made of uPVC or glass with aluminium/wooden frames. Can be fixed to walls.
Excellent for hardening off plants.
Small size limits what you can grow.
PROS: DIY fixed version is cost effective.
Excellent for hardening off crops.
Mobile versions great for warming soil in spring for early crops.
CONS: Plastic versions liable to blow away.
Heavier wooden types can be expensive.
TOMATO HOUSE/MINI GROW HOUSE
PROS: Cheap, easy to move.
Dismantles easily for winter storage.
CONS: Likely to blow away.
Shelves bow under weight.