Are You and Your Plants Crushed by Heat?
I had to take a break in the shade. It was over 30 C, the sun was beating down and I was thinking I might be getting heat stroke. So I stepped into my greenhouse to cool down.
Wait a minute. Cool off in the greenhouse? That can’t be right. And for the first ten years of greenhouse growing it was wrong. In summer I only worked early morning or late evening. But that has changed now and every part of my greenhouse experience is better because of one simple change.
I installed shade cloth on my 16’ x 20’ all-poly Cross-Country model BC Greenhouse in early May. Now I know: I should have done this little job in the garden years ago – but better late than never. It took less than an hour and we admire the difference daily. Our greenhouse is orientated from east to west so the widest part of the house is exposed to sun in the south. We placed the cloth we purchased at a landscape supplier over the top of the greenhouse peak allowing cloth to fall mainly to the south but also along the north side over the vents. We started reaping the benefits right away.
I had stalled installing shade cloth because I thought, wrongly, that plants needed all the light they could get. That’s the benefit of a greenhouse right? I want strong sturdy plants.
Heat builds up in the enclosed space of a greenhouse and eventually something has to give. Usually what gives is the health of the plant. I tried fans and a thermostat controlled cooling system but it was all just band-aides. So after 10 years of stressing plants without shade cloth, I made the decision. Last week I installed 47% shade cloth over the top of the greenhouse.
Helpful Husband and I pulled the grommet-edged shade cloth over the greenhouse by tying a rope to the first pair of grommet holes on one end and, while we were on either side of the house we lifted it over the roof and over the already-open vents. It was a hot day when we installed the cloth and I might have been complaining a bit.
As the cloth went up it was like a cloud passing over inside the greenhouse. The shade from the cloth dropped the temperature indoors instantly and the fans and cooling system shut off automatically. A week later, the cucumber plants have doubled in size and hundreds of Iznek miniature cucumbers are forming.
Now when I find myself too warm outdoors mid-day I can pop into my greenhouse for a little rest. I added a padded chair and side table with a pot of succulents so the space feels like a waiting room, not a sweat chamber.
I am not sure why I was so slow to learn this lesson but I want every greenhouse owner to adopt it. If you don’t have shade from trees or other buildings add it now with cloth. If you have a glass-roofed house add cloth with up to 70% shade to keep the heat of the sun from building up inside your sheltered cozy space.
It’s better late than never and if you don’t want to be crushed by heat this summer add shade now. Both you and your plants will thrive while other growers sweat and suffer from heat stroke.
PS If you have been following this little blog you know I promised Helpful Husband his favorite crop, potatoes, by the end of May. To make this work I started some potatoes in cloth grow bags. I placed the cloth bags on heated soil inside my otherwise unheated greenhouse in February. I covered the bags with fleece to keep the heat in until night temperatures were settled and potatoes were well up. And it worked! Tonight we are celebrating our first potato harvest! Let me know what you are celebrating in your greenhouse and garden this week.
For more great tips from Donna, visit www.donnabalzer.com. You can also read Donna’s gardening books: No Guff Vegetable Gardening with Steven Biggs and her just released Gardener’s Gratitude Journal: Part Diary, Part Personal Growing Guide.