For the first three years of my gardening 'career' I grew without polytunnel, although we did have a tiny greenhouse. We managed ok, we used low tunnels and cold-frames to great effect and by the third year we were self-sufficient in veg and seasonal fruit all year round. I've covered the general range of options for growing under cover in the basics section of this eBook.
However when we got a polytunnel, everything got so much better. Not only were we able to grow more food and a wider range of food, but more importantly we had a lot more fun doing it. The polytunnel is such a lovely space to spend time in! It's also a great space to retreat to in winter, to warm up, shelter from the rain, or chill out and have lunch.
Then we got a greenhouse at home, which meant we had electricity, which in turn meant we could heat and light it. This section of the book is a celebration of greenhouse growing!
My greenhouse is 14’ by 8’ and it’s a Robinson’s model, from The Greenhouse People, just like the polytunnel, it’s the biggest that I could fit in my garden and the same logic applies, the marginal cost of a bigger greenhouse gets lower as the greenhouse gets bigger.
Living half a mile from the sea, it’s very windy, so we went for a very strong greenhouse construction, here’s a quote from their web site:
Robinsons are probably the strongest greenhouses in the UK today, but not simply because up to 35% more aluminium goes into the manufacture of the frames. Whilst other greenhouse companies often use inferior T-shaped section glazing bars, Robinsons have designed a unique box section glazing bar, creating a far more robust frame, which is absolutely vital for strength in windy conditions
My greenhouse is oriented North/South, because that’s the way the garden is oriented, I prefer the east/west orientation of the polytunnel on the allotment, because west to east is our prevailing wind direction, but I didn’t have that choice.
I added a second double door, because this allows for free flow of air in summer and allows me to open at least one of the doors on windy days, although the greenhouse already comes with good ventilation. The following link is to the model I purchased.
Robinsons Royale 8ft6 x 14ft9 Anthracite DWARF WALL
The greenhouse was designed to be a multi-functional space, providing a large dining room, sun lounge and growing space.
Setting up the greenhouse for Christmas dinner
I’ve decided to keep my greenhouse frost free all through winter, and from April, I’m going to start heating it to about 10°C at night. Keeping it frost free this winter has cost me about £10 and I’m hoping that keeping it frost free from April onwards will cost me less than the harvest value of the early fruits that I pick in late spring and early summer.
There are a lot of considerations to work through when designing a greenhouse. I’m going to step you through the design decisions that I took, your decisions might vary.
The general advice is always to get the biggest greenhouse that you can afford. This makes sense for two reasons, a greenhouse is such a lovely space and you will always find ways to use that space and because the marginal cost reduces as the size increases.
I went for a 14’ by 8’ greenhouse and this size was dictated by two factors, first we wanted to be able to seat 12 people for meals and second because this was the space we had available in the garden without losing too many outdoor raised beds.