I just barely put in a greenhouse! It has three 50-gallon rain barrels inside, and I have three 250-gallon IBC tanks on the north side. All of those will be filled with captured rainwater.
I’m hoping those will cumulatively serve as enough thermal mass to make my coldest winter days zone 8b in there, rather than 7b. If I can consistently keep it two zones warmer, as in 9b, I could get away with a whole lot of fruit trees I’d really like to grow, which would be awesome.
I’m suspecting that it may serve another valuable purpose in winter, too: keeping the soil moist, rather than sodden. Our winters are when we get most of our water, and I think that may be highly problematic for plants that don’t grow in winter and don’t like wet feet (a.k.a. bananas).
I’ve put some banana pups in there over the winter to see how they do, and I’ve also planted a whole bunch of ginger, which is hardy to zone 9a, and is in the same order and wants similar growing conditions. I figure if I can keep ginger alive in there, it’s a good sign for other zone 9a perennials I may want to test out in it later.
Last Thursday, right before our first hard freeze, I covered my best squash plants with three layers of greenhouse plastic, with about 10 milk jugs filled with water around their roots. I assumed they’d die, but I wanted to see if I could get away with doing that to keep them alive.
Imagine my surprise and delight when I found that they’d lived! The outer leaves are wilted and brown, but the inner leaves of each plant are doing well, as are the main stems. Two of the plants had a brand new female flower open this morning, so I happily hand-pollinated them. Maybe I’ll get little bitty summer squashes, or maybe I’ll be able to keep the plants alive long enough for them to give me fruit old enough to finish maturing indoors and give me viable seeds. Wouldn’t that be something?
I’m going to see how long I can keep those squash plants alive and bearing new fruit. Removing the plastic every morning and putting it back every late afternoon is a bit of a bother, but one I’m happy to do for right now. It’s a fun experiment, and it’s a really hopeful sign that I can keep perennials alive that are almost hardy enough for my zone!
Hmm, come to think of it, if I want to see if I can get away with zone 10a plants (most tropical perennials I’m interested in), one way to do that would be to try keeping zucchinis alive in the greenhouse all winter. Those winterkill at freezing, which is the same temperature that zone 10a perennials do. It’s no big deal at all to risk a squash plant as a canary in a coal mine; I have oodles of squash seeds. Yes, this is an experiment I should definitely try running!