Container gardening is ideal for the small suburban backyard without much space. It is even better suited to the arid climate because the required water is much less—in my system I water less than twice a week and use less than a gallon. I’m using a container gardening system worked out by others, and it is really impressive. My father put me onto good video documentation as well as EarthTainer’s excellent guide for soil composition. The video discusses using aluminized bubble wrap, sold as insulation. I did not initially wrap my buckets in insulation. An experiment is in order.
My tomatoes are dying. The leaves have started drying, browning, and curling. Older leaves are failing first. My diagnosis is an untreatable fungal infection called Verticillium wilt fungus or Fusarium wilt fungus. The symptoms, according to gardeningknowhow.com, include worsening wilting after watering. My cherry tomato has produced three fruits, none of which are likely to be eatable. Look carefully, you can see a hornworm with more hope than promise.
Apparently soil temperature can influence the spread of Fusarium. Temperatures above 30 C (86 F) contribute to the spread.
I put a thermal probe in each of my two containers for a day. After a day I wrapped one of them in insulation and placed white foam core on top. The buckets are in different positions, so I’m not looking at the difference from one bucket to the next, but rather the change in the difference. I plotted the soil temperature in each bucket over the course of the experiment, along with the air temperature.
The result shows that the insulation helps quite a lot. It lowers the peak container temperature by 3 to 4 degrees F. More importantly, it kept the soil temperature below 80F despite higher air temperature; that should help control fungal growth. In the New Mexico High Desert the insulation should not be considered optional. Partial shade may also be beneficial.