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Growing under glass: fit your garden & budget

Growing under glass is incredibly rewarding, expanding the range of plants you can try.

Greenhouse, conservatory
Greenhouse when first built with conservatory above

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’ aren’t called ‘blow-aways’ for nothing – not great for windy or exposed sites.

I had a bad experience with an 8’x4′ grow house, which retailed at nearly £100 and was wrecked after three days.

Panels blown out in Storm Desmond, January 2016
Panels were blown out in Storm Desmond, January 2016

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. I had mine done by Mark Barry, of BMA Builders, South Shields – email bmabuilders@hotmail.com.

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.

Greenhouse shelves
Handy seed tray sized wall mounted shelves which fold flat or can be used as tomato supports

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-logoPotted guide: undercover gardening

The pros and cons of undercover structures:

GREENHOUSE

PROS: Permanent.
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.
Danger of cheaper horticultural glass shattering.

POLYTUNNEL

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.

CONSERVATORY
Tomatoes
Conservatory packed with tomatoes in June

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.

GROW HOUSE

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.

MINI GREENHOUSE

PROS: Strength of those made of uPVC or glass with aluminium/wooden frames. Can be fixed to walls.
Excellent for hardening off plants.

CONS: Expensive.
Small size limits what you can grow.

COLD FRAME

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.
Not durable.
Shelves bow under weight.