Solar Cold-frame Success: A Case Study

“We really wanted to make a greenhouse,” explains Mike Fuller, “but we just couldn’t seem to drink the lemonade quickly enough!”

Mike’s sons, John and David, it seems, had seen a programme on the TV about building a solar greenhouse from old plastic bottles, and set their hearts on making one for themselves, but unfortunately, they were still several hundred bottles short and time was moving on. With spring in danger of soon becoming summer, wife Katy came up with the answer – doing it on a much smaller scale – and so the idea of the solar cold-frame was born.

“I couldn’t bear the look of disappointment on their little faces,” she says. “We’d have had to drink gallons before we would’ve even got half way. I reckoned we’d already got enough clear bottles to make the top for a cold-frame and this way we could use some of daddy’s brown plastic cider bottles to make up the sides.”

Modifying the Design

They’d managed to find plans on the internet for building the greenhouse they’d originally wanted, but they couldn’t find any for the new cold-frame, so undaunted Katy set about modifying the design.

“Actually, it was quite easy. The basic idea was the same, so all I really had to do was work out roughly how much wood I needed to make up the frame. I did go a bit wrong at that stage and had to go back to get a few lengths more, but it all worked out OK in the end.”

Taking Shape

They used the same construction techniques as most recycled bottle greenhouses, cutting the bases off the bottles and threading them onto garden canes to make a series of rows, which are then fixed to the actual frame, to make each individual panel.

“I couldn’t work out how to make the front sloping,” admits Katy, “so I just settled for a box shape, about 20 inches high by two feet by four feet. The bottom couple of rows at the back, front and sides were brown and we used lemonade bottles for the rest and the top. We all helped and we’d finished it in no time.”

Planting Success

After putting it in pride of place on their patio, the next stage was to get sowing.

“That was the bit that the boys were really looking forward to,” Mike says – and by all accounts they seem to have done a pretty good job. They planted a whole range of things, both edible and flowers, with very few failures, which is about as good a start as you could wish for any young gardeners. It also meant that the family got to enjoy a plentiful supply of home-grown lettuces and runner beans throughout the season too.

Summers are short in the north of the country and it wasn’t long before the local weather forecast was full of talk about the threat of frost – which gave Katy another idea for their new cold-frame.

“We’d joked about it being a solar cold-frame, but it was really noticeable how very much warmer it stayed in the sort of sunny days and clear nights that usually send the temperature tumbling. I thought it would be a great place to protect some of the more tender plants we had.”

In went the geraniums, begonias and the other less hardy varieties in their garden, and not a single one was lost despite one of the coldest winters on record. “Katy was overjoyed,” says Mike, “I just wish we’d built one ages ago.”

It sounds as if they’ve got the bottle-building bug; apparently granny’s getting her own cold-frame for her birthday, and they certainly haven’t shelved their plans to build a full-size greenhouse one of these days – but they’ve a few hundred litres of lemonade to get through first!