The greenhouse is pretty much filled to the brim. I have plants on all of the shelves and even on the ground, so you can imagine my trepidation when the forecast called for 26 degrees. I wasn’t sure if my heat mats would remain lit through the night. It was time to go to plan ‘B’ to mitigate losses in case of a heaterless night, so I brought in the most tender vegetables, such as my special Hungarian medium hot block peppers, basil, celery, and squash plants.

Experimenting with Heat Mats

The bulk of the tomatoes I set on the heat mat. The onions, broccoli, kale, kohlrabi, and cabbage had to fend for themselves.

As I’m shuffling around flats and hauling in plants, I was struck by the difference in my basil plants. I’ve included a picture in this post. Keep in mind these were seeded and eventually transplanted at the same time. The only difference is the healthier plants were on the heat mat. The others weren’t. The peppers from the heat mat share the same qualities. They look so much better.

I’ve used the heat mat for many years, but I doubt it was on quite as much as I had it plugged in this season. April was terribly cold and gray; May hasn’t been much better. So instead of unplugging it during the day, I often left it on. Now I wish I had enough for all of my shelves, because the health of the plants is remarkable.

Growing plants in a greenhouse can be a tricky business as far as pests and plant health. The closed conditions are also ripe for disease and pest outbreaks. One consideration I have to take is to minimize the impact of any fungal issues, particularly when we have cold springs like this year. The second basil flat definitely suffered from it, so I can only conclude one way to work around them is to utilize a heat mat to increase the plants’ overall health.

Bringing Plants Inside

Various flies, mites and aphids can also cause issues in a greenhouse setting. While I don’t know if my wonderful heat mat can do much about those (except to possibly keep the plants healthy enough to sustain an attack from pests), one thing I’m vigilant about is using new soil and being careful about bringing in plants from outside sources. I’ve had more issues when I’ve done cuttings, then from anything I’ve started from seed. In other greenhouse situations, the use of sticky traps helps cut down on the number of pests. They stick on them and that’s that.

A good reminder in any situation, whether it’s a greenhouse or open garden is to maintain the balance of pests and predators as much as possible. Last year we visited a brilliant young man in Bozeman who is on the cutting edge of permaculture design. He has the indoor greenhouse I want so badly, and talked to me about keeping the balance of pests/predators. When there are a lot of aphids, it gives something for the praying mantis and other predators to eat. For the most part, it does find a level that works on all accounts. (You might have a few holes in plants in the process, but try to look at the big picture.)

I’ve rambled a bit in this entry, but it all started because I am truly impressed with the benefits from using that heat mat. We’re just about at the point where plants will go out in the garden for the season, but I’m going to make a point of buying another mat next year and keeping it on a whole lot longer than I used to.