i got that experiment on the go right now as we have had a few freezing nights.
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so, in the lab(ground) in front of my garage facing south. in raised beds, sheltered from most winds and weather, except cold are: 1 dundicut, 1 goatsweed and 1 jwala.
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-3C was the first extreme night, all have survived but the dundicut has drooped, is wilted and has dropped some leaves. its fruit has softened but not mush. the plants are staggered in the raised bed with the goatsweed being closest to the garage and having the most protection. then jwala is 6 inches in front of the goatsweed and the dundicut is 6 inches in front of the jwala and the dundicut is closer to any cold exposure. the jwala fruit is still ripening and firm as is the goatsweed.
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i do cover the plants at night and have 2 remaining tomato plants next to them for any possible additional heat. plus, they are right beside my greenhouse, that hits 50C when the sun is out, it has a cement floor covered by black shingles, so i am guessing that is retaining heat in the soil during the night. Â farther away from the greenhouse, i dug in some coffee grounds yesterday and found some ice pockets. i do monitor the greenhouse temps with a remote thermometer and by 6am it has gone as low as 4C at the top of the greenhouse, i don't know what ground level or below temps are, perhaps i should move the remote to the bottom of the greenhouse to see if the ground level is retaining heat.
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last year i attempted a fully exposed goatsweed in my unsheltered garden and a -7C took care of it. the 3 lab rats are destined for the composter once the experiment is over.