lisa-rayner:
Growing tropical fruiting vegetables in cold climates
Adapted from Growing Food in the Southwest Mountains: A guide to high-altitude, semi-arid home permaculture gardens:
Many popular garden vegetables are tropical in origin, including many vegetable fruits in the Solanaceae and Cucurbita families such as tomatoes, peppers, eggplant, melons, squash and cucumbers. They often will stop growing if the temperature drops below 50°F. Fruit maturation takes longer in cooler temperatures, too. Right now, nighttime lows in Flagstaff are in the mid 40°s.
Flagstaff’s last spring frost has historically been around June 10, although climate change appears to be pushing back that date. However, there is a small chance of frost throughout our entire growing season. I tell people in Flagstaff to not bother growing eggplants and melons outdoors without high-tech protections from the cool night temperatures such as Wall O’ Water Season Extenders (there is some evidence that the red ones help tomatoes ripen faster than the green ones used here). Bell peppers are almost as difficult to grow outdoors, as are large winter squash varieties.
The top three photos I took this week at Juniper Street Community Garden, which I used to coordinate and where I formerly gardened. The tomato plants in the Wall O’ Waters are in a plot cared for by long time community gardeners at this garden. If this was my plot, I also would have inorganic mulch, as I explain below, tucked around the Wall O’ Waters to prevent soil moisture from evaporating and provide extra heat at night.
If you live in a cold climate with a short growing season you must make use of all possible ways to keep these crops warm, especially at night, and protect them from late spring and early fall frosts.
The easiest of these tropical crops to grow are summer squash, small winter squash varieties, grape and cherry tomatoes, small chile pepper varieties, and some cucumber varieties.
Choose varieties that have been bred for short growing seasons and cooler night temperatures.
Start seeds indoors and transplant seedlings outdoors as early as it is safe to do so. You need to make the most of the short growing season.
Use microclimate-warming techniques like creating parabolic sun traps around your plants or garden beds using earth, rocks, straw bales or other materials.
Use dark colored inorganic mulch such as dark rocks. The squash photo is from one of my community garden plots a few years ago. I collected dark grey basalt rocks and used them as mulch around my plants. Rocks are thermal masses. They absorb sunlight and radiate the energy back out at night in the form of heat. Mulch also protects the soil from wind erosion, shades the soil, and prevents soil moisture from evaporating. The organisms that live in healthy garden soil greatly appreciate soil and soil moisture protection measures. Thermal masses also keep the microbes and larger soil organisms more active.
Row covers, water jugs and other protective elements might be necessary. See my post on how people protected plants without petroleum products.
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