Wednesday, April 18, 2012

Coldframe Pros and Cons

I'll say up front that we love our walk-in coldframes. Winter gardening will just never be the same again. But in our Tennessee Valley climate, especially with the unusually warm weather in March, they do have one big drawback. They get much too warm for good results with brassicas. We have tried various methods to produce spring crops of broccoli, cauliflower and cabbage without having to resort to almost daily sprayings with Dipel to keep the cabbage butterfly larvae from ruining the crop. We were hoping that the coldframes, which physically prevent the butterfly from reaching the plants to lay its eggs, were the answer. Alas, no. Even with all the windows open, the temperature climbs into the upper 80s on sunny days. We may get some decent cabbage, but broccoli and cauliflower would not tolerate the heat.

So instead of brassicas, we have planted some early beans, and we will soon be replacing the cabbage with squash and cucumbers. We plan to try some fall-planted brassicas, so the plants will be maturing during cooler weather in November and December. In the meantime, we may figure out some way to ventilate the coldframes better, while still screening out the cabbage butterfly. Stay tuned.

Recycle Beer Cartons as Weed Blocker
If you are planning on building a new raised bed and wondering how to deal with existing sod or weeds, you may have considered placing a weed blocker fabric over the undesired plant material. This works great, and you can build a bed right on top, but there is a free alternative: beer cartons. Those trapezoidal twelve-packs that bottled beer comes in make great weed blocker. Separate the cardboard at the glue seams and fold the container out flat. You will see that the flattened cardboard pieces can be interlocked, owing to the way they are die cut. A single layer of these interlocked pieces stops even tough weeds like poke and dandelions. It takes about 18 months for the cardboard to break down, which is plenty of time to eliminate all the weeds under the raised bed. Weedblock fabric, by contrast, does not break down at all. And it does not come packaged with a frosty beverage.

Local Food Report
The first local strawberries have appeared in the market. The ones at Three Rivers Market came from the Colvin Family Farm in Spring City, TN. They must have been forced in a greenhouse, but they are far tastier than the berries now coming in from Florida and California. Good work, Colvin Family! Several varieties of lettuce, along with beautiful rainbow colored Swiss chard, from Hines Valley Farm in Loudon County were also on offer. Watercress from Hancock County appeared to have been foraged. Wild watercress is better than cultivated, in our view, and the harvest of wild watercress is certainly not environmentally harmful.

Speaking of wild veggies, I am surprised that we don't see more foraged greens in specialty markets like Three Rivers. Besides watercress, there is upland cress (or "creasy greens" to oldtimers hereabout), along with poke salad, dandelions, wild asparagus, wild onions and many more. I used to go on foraging trips with my grandmother, who believed that eating a good mess of wild greens was beneficial to one's health. I also wonder why ramps never seem to appear in the produce section, despite having a degree of popularity among upscale chefs in the big cities.


Erik said...

Have you tried a shadecloth for your cold frames? Here in the northwest, we don't get too hot even in summer. But inside my little greenhouse it easily reaches 100+ on our very long summer days. That's too hot for almost anything since my plants are all in pots. I've used two tricks in the last couple years. One is a shadecloth on the south facing side of the greenhouse. The other is a series of misters on a timer, like in the produce section. A couple minutes of misting every 15-20 minutes worked great. I set up the misters on a hose weaving through the space, pointing up from the ground. This allowed me to cool the containers and create some temp variation without overwatering the foliage. If you were feeling fancy, you could get a thermostat to control when it misted.

John Tullock said...

I do plan to try shadecloth this summer, and will report back as to how well this works.