I'm doing the lasagna thing for the first time this year. It'll be flowers, not veggies. I hope it works, because I'm trying to kill off a weedy mess. I called a locallly owned appliance store for the cardboard. They told me that a particular two days of the week are the best times to come by. I've gone by twice and filled my station wagon with washer & dryer boxes both times. I used the first batch to cover a large area that I wanted to mulch. It used to be an area with ugly grass/weeds between two of my flower beds that was hard to mow. It looks much better now, and my pumpkin & watermelon plants are enjoying crawling up into the area. No crabgrass has shown its nasty self so far. Early this spring, I did a similar thing with newspaper around my veggie beds, because I was tired of all the weeds growing into them. It's been fantastic all season - almost no weeding. The cardboard was a lot faster than the newspaper - it took practically no time to get it positioned. I'm lucky in that a local horse owner leaves bagged horse manure free for the taking. But I've heard most barns will let you help them clean up in exchange for manure. (Gee.) And at my local dump, I can get virtually unlimited grass clippings & leaves. I've heard calls to locally-owned landscapers will yield grass & leaves in the appropriate seasons. Sure, I'd love to know that they weren't treated with anything, but I figure in the end the benefit outweighs the risk. If you connect with landscapers, you have even more control. A locally-owned coffee shop (getting the theme yet?) will collect coffee grounds for me if I just leave them buckets. I bought a couple at Lowe's for a couple bucks since I felt bad leaving kitty litter buckets (the ones I had handy) at a food establishment. Starbucks has a program for this, too - you can go into any Starbucks and pick up used coffee grounds. You don't get a lot of volume that way, but if you're driving by - heck, it's free. Apply cardboard, then compostables. In my case, let it all overwinter and plant next spring. Sure sounds easier than the double-digging I did for my veggie beds! Especially when you consider all the granite rocks we had to haul out here in New Hampshire. When I lived in the SF Bay Area, they used to use goats to control weeds along some roadways. People had herds & portable fences they rented out. I thought that was pretty cool.

Patti: You are a long ways north so in summer will get a good morning and afternoon sun thru the east and west walls. At most I'd insulate the north wall. If it is insulated and reflective then it will add more light than it loses. I like the corrugated polycarbonate but if you plan to heat in winter consider the twin wall polycarbonate. Both come in types that diffuse the light, a plus IMO. Something like Solar Soft 85, or maybe 90, would be my first choice if building another greenhouse in an area with low heating cost. If heating costs are high the same type material in twin wall. Here is a link that might be useful: Solarsoft 90

I use 4' wide strips of woven, black polypropylene weed barrier in my garden, and it actually works, more often than not, as insulation, keeping the soil cooler and a more even temperature and moisture. There are small air pockets, a few layers of organic mulch and compost from the growing beds under the plastic, giving a pretty good heat transfer barrier. An interesting phenomenon is to be out there transplanting stuff, and the black plastic is almost too hot to touch so I need to sit on a bench, and the planting soil is cold. I routinely grow cool weather crops like spinach, peas, fava beans, and so on with the weed barrier right up to the stems. It certainly would be worth a try, but I'd keep the layer of newspaper down to the bare minimum, like one sheet, to stop weeds and allow the best transfer of heat energy. Otherwise, the paper would act like insulation and actually might keep the soil cooler. I proved to myself this past summer the difference on soil temperature and growth rate of both tomato and eggplant. Soil in a 10 gal container heated up considerably faster and the plants grew at least 2x as fast, yielding at least 2x as much as the garden plants. Now, if I can figure a way to heat the soil in an entire bed.....

Technically evaporation and boiling are two different mechanisms driven by the same thing, vapor pressure. Evaporation occurs at a water/air boundary while boiling occurs within the liquid itself. Also, by definition, steam can only be caused by boiling and not evaporation. So evaporation cannot occur in the panels but only at the pool surface and boiling will not occur until the water reaches 212 deg F which is not possible because of heat loss. However, as the water heats up in the panels, the water density decreases and it will start to expand. In a closed system, this will cause an increase in pressure but what we are talking about here is not a closed system. The panels are connected to the pool and water will migrate towards the pool equalizing the pressure. It is not possible for pressure to build up in an open system. But even in a completely closed system, the panels would still not burst because the change in volume of the water is very small and can be absorbed by the panelâÂÂs elasticity. Water going from 85 degrees to 212 degrees will only expand by 4% (see link) which is easily absorbed by the panels. Also, I was not proposing to close the valves with water in the panels. The valves should only be closed when the panels are EMPTY (i.e. full of air). This can be accomplished with a vent valve and a drain valve and with the isolation valves closed. But again, I don't think this is necessary and there are also a lot of examples to illustrate this point. There are many pools operating today that allow water to sit in the panels without any ill effects. One thing to keep in mind is that when an automatic solar control shuts off a solar system, the panels do not drain automatically UNTIL the pump is shut off so many installed systems today have water that sits in the panels with hot sun beating down on it, including mine. In addition, there are many panels installed that do not have vacuum release valves with the panels sitting on the ground and so never drain unless manually drained. Most AG pools are plumbed this way. If this was a problem at all, there would be a lot of people reporting burst panels. But again, the physics simply does not support bursting panels. Here is a link that might be useful: Properties of Water