I have a room in my house that is very drafty and if I let it stay cold it keeps the rest of the house cold. I brought this heater from Target last year, I keep it on 24/7 on a low temp and after about a day running it has kept the room comfortable although not real warm. If I turn it up it will be smokey hot in there which I did not want to do. It has solved the problem. I checked my light bull and it did not change significantly over the year. I am wondering if this might be a solution for you? You are in zone 7 like I am and I have had no need for supplemental heat outside yet and my birds seem to be doing fine. Their whole pen is made of wire mesh with a box for them to go in at night. The temp has gotten pretty low and when it did the chickens stayed in their box huddled together for a while but for the most part they were business as usual. I did close their box on really cold nights though to keep out the drafts. HTH Here is a link that might be useful: heater

We have a bed each of yellow summer squash and cucumbers planted in black plastic. We planted them a couple of months ago. The squash plants are starting to form little fruits, about 3 inches long right now. We put a row cover on them and they have survived some low temps: one night of 31 degrees, and a couple of 35 degree nights, many nights in the upper 30s. The row cover creates a warmer environment during the day so they grow faster. In the portion of the bed that doesn't have row cover, the plants are about 5 inches tall. Under the cover, the plants are about 24 inches tall. Makes a huge difference! The uncovered plants were killed back by the frost but some of them are putting out new growth so the roots obviously weren't killed. Our daytime temps have been in the 50s for a week or more and the plants are growing well. The row covers have been in place for about three weeks now. We need to uncover the cukes during the day for pollination. Our honeybees are still out and about during the day. This week is supposed to have highs in the 60s. In spring we keep row covers on our eggplant to protect them from flea beetles. It makes them grow much larger and faster. We take the covers off when the plants start to bloom.

Michelle: my question is why don't we want to use plastic, and by doing so, why can't it touch the plants and leaves? You can use plastic if that's all you have, and lots of people use clear plastic wrapped around tomato cages, etc. for its greenhouse-like effects. It's just that there are better insulators than plastic. The not touching the leaves thing is probably for two reasons: 1) It's the air trapped under the plastic that insulates the plants, and where the plants touch the plastic, there is no insulation, and, since the plastic itself is a poor insulator, it will essentially conduct the cold directly onto plant parts in contact. With things like actual frost blankets, etc., there are also tiny air pockets in the cloth itself that provide insulation. Plastic doesn't have that. Think about how well you can feel hot and cold through plastic gloves vs through cloth gloves. 2) Moisture condenses easily on plastic and stays there, and parts of plants that get wet during a frost can be more damaged than parts of plants that stay dry. Frost cover, etc. tends to be breathable and wicks moisture so doesn't present this problem as badly. I don't think it's a big deal if a few bits and pieces here and there come in contact with plastic, such as would happen if you wrapped a tomato cage in plastic. But sometimes people misunderstand wrapping and do it too tightly.

If you're in Alameda, it's a lot less likely to have frost because you're surrounded by water and are well inside the Bay. I live in Oakland, straight down High St. halfway up the Oakland hills, and our Meyers and Bearss are in the ground. Occasionally the fruit gets nipped by frost (interior dries out) but the issue is in-ground plants don't suffer because the ground NEVER freezes here. You may want to be more careful with container plants because most people use the smallest containers possible since large ones aren't easily moved....and smaller pots may be more susceptible to frost nipping. Keep them a foot or so off the ground; that will avoid the coldest air currents. Setting them against a south- or west-facing wall will help, too.