What is a poor man’s greenhouse and how can it help me with my gardening?
It’s incredibly simple and you can use recycled materials to build a greenhouse for the poor (In fact, that’s what I’ve always done!). All you have to do is join the ends of four fairly wide boards to form a square or rectangle. This simple frame can then be covered with glass (an old window frame or old wooden shutters, for example) or some kind of plastic that lets in light. It is best if this bottomless cold frame can settle on a slope that slopes slightly to the south. This provides maximum exposure to the sun’s rays and will keep the box warmer.
As we all know, glass tends to heat up anything below it and this is the purpose of the glass on top of the poor man’s greenhouse. Also, those new plants need sun and warmth to grow to maturity properly.
The reason for building cold frames or seedbeds is to have time, either in early spring or late fall, to grow plants in a frost-protected location. (Most people use cold frames more in the spring when they are starting new plants, but they can also be used to extend the growing season into fall.) At this point, you can plant seeds in the soil below the box, or you can put starter flats inside it. I usually start my plants inside the house and then transfer the plants to the seedbed before putting them in the ground to ensure the plants properly “wear down”. If you find that the weather is hot, raise the cover of the seedbed and that ensures protection from any wind as well as most small animals and ensures that the plants are worn out.
A cold frame will retain its own heat quite well, but it needs extra protection on very cold nights. If you hear that the temperature is going to drop much below freezing, cover the box with a tarp or old blanket just to be safe.
I was told that for excellent seed germination in a seedbed, after placing the glass sheets or cover, stretch a solid sheet of clear plastic over the sheet and seal it with soil around the edges. Apparently, the plastic-enclosed seedbed provides the warm, humid conditions that seeds love. However, it is essential to monitor the temperature during the middle of a hot day. It may be necessary to open one end of the plastic for excess heat to escape.
Bright sun can be a problem. Gauze spread over the cold frame cover will prevent sunburn.
A hotbed is the same as a cold frame, except it has some sort of artificial heat source. An inexpensive way to create a heat source is to build a three-sided box next to a basement window, leaning it against the foundation of the house. If you leave your basement window partially open so heat can flow into the frame, you can keep your plants from freezing for most of the winter.
Other less economical methods include electrical heating cables under them, or you can use some sort of small heating unit. It doesn’t have to be very hot. Remember that you don’t have to keep the temperature in this mini-greenhouse as high as you would at home.