-3 C in the greenhouse

14 years ago

The greenhouse got down to -3C overnight. It was 0C at 11:00 PM so it was below freezing for most of the night. I lost about half my ws tomatoes and an ivy geranium doesn't look healthy. Other than that everything looks fine. The survival of the tomatoes seemed to be related to variety. Ironically, the sub-arctic plentys are gone. Sophie's Choice looks unscathed. Purple Prince and Sweet Millions are about 50% or less. It's supposed to be below 0C tonight but today is sunny and the greenhouse is heating up. It's been holding about 3C above the outside lows.

My tomatoes under lights are ready to pot up but I decided to wait until after this cold spell. They will be bigger than they should be but not dead.

Comments (6)

xaroline
14 years ago
I hope that you have lots of cold sinks in the form of pails of water in your
greenhouse to take up the cold?
stanly
14 years ago
Last year I installed an old furnace I inherited in my greenhouse and during the last week, the furnace has been running a lot at nite even though I have it turned on to +3C in the greenhouse for overnite. Supposed to warm up this weekend so that will be nice. Stan
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DrHorticulture_
14 years ago
Mine maintains about 5 C warmer than ambient on calm, clear nights, 2-3 C warmer on windy nights. Did you find the heat differential more favorable in the fall? Just curious.

I only have frost-tolerant crops (peas, spinach, brassicas) planted in the greenhouse but they still show some freeze damage from the hard frosts earlier this month. I have eggplant seedlings in my heated sunroom ready to replace them in June.
ljpother
Original Author
14 years ago
I didn't check in the fall. I took the water out in the summer. This year I'll leave most of the water in (my rain barrel will be a rain barrel again) and try growing some plants in the greenhouse (sweet potato, tomatoes).
heavyoilguy
14 years ago
I built my greenhouse last year and I have 6 - 25 gallon drums that are on the north
wall , painted black and full of water,I made my potting bench over the top of it , There is about a 4 deg c difference right now , I also have tried this year- built a 6' x 2' x 12" high box. installed a 100 watt light bulb inside , and use a piece of plexiglass to cover, Yesterday it was 0 outside and it was 18 c in the box, which is in the greenhouse, Cheap heat.
stanly
14 years ago
I really like your idea about the box with the light bulb inside and I think I will build one tonite because it is certainly cheaper to run a 100 watt bulb than a furnace overnite. I am doing containers for some customers, only 12 customers but about 30 hanging baskets and about 30 containers so in a small 10' by 20' greenhouse, I use every inch of space available. I already have 21 hanging baskets built and about 12 different size pots, from 12" to 18" so this weekend will be very busy. Thanks for the idea. Stan