Even in Louisiana it gets cold in the winter, and it’s useful to have some sort of greenhouse or cold frame to keep those tender plants going through cold spells, or to start seedlings in the very early spring.
I’m not sure if I invented this, but I have no doubt it’s the least expensive and most versatile greenhouse you can make in under fifteen minutes. It doesn’t win lots of points for beauty, but for just a few bucks what do you expect?
Materials and construction are incredibly simple. Buy some ten foot lengths of white pvc pipe (you will need a minimum of three, and the smaller the diameters are more flexible) and some fairly heavy-duty plastic (6 mil in a 10 foot width). Shove the pvc pipes into the ground where you want to situate the greenhouse and bend them into an arc. All you need to do now is drape the plastic over this structure. Voila! Total cost: about $12 max.
To keep the plastic from blowing off, you can weight the ends down with bricks, stones, or dirt. This is by far the simplest method, but I prefer to staple some scrap wood to the end of the plastic. This allows me to roll up unused portions of the sheet (like a toilet paper roll), and it’s just a bit neater.
One of the great advantages of this greenhouse is that it is infinitely adaptable and portable. Just shove the pvc pipes wherever they are needed, when they are needed, and move as required from one spot to another. And it’s easy to store in the summer.
In a fit of ambition, I once made a frame out of two-by-fours, with holes into which I insert the pipes, because I wanted something that seemed more permanent and symmetrical. But I wouldn’t bother: it isn’t necessary and limits you to the size of the frame.
The plastic will last for a couple of seasons, but eventually will have to be replaced. Not a big deal. The plastic alone won’t keep your tender plants safe if it gets really cold, but when that happens I put some movers’ blankets over the plastic, and run an extension cord out to power a 100 watt bulb that I hang inside the structure. Since most of an incandescent bulb’s power goes to producing heat, a 100 watt bulb will keep this small greenhouse quite toasty at night for just a few pennies, and actually looks very cool! Think of it as a night light for your garden.
I’ve also made cold frames out of discarded shower doors. About ten or fifteen years ago tempered glass shower doors apparently became passé, and I picked up a half-dozen from various the neighbors’ garbage. This also works fairly well, especially for starting seeds and for small plants, but there isn’t as much head room as there is with the pvc-greenhouse, which, depending on how you place the pipe, can offer quite a bit of space--plenty to allow you to crawl around inside if you are so inclined.
Here’s the basic structure, shown to illustrate its absurd simplicity. Note again that it doesn’t win any beauty contests, but is perfect for the lazy gardener like me.
Oh, so you don’t think I need a greenhouse in Louisiana? Check this out: a very, very rare snowstorm on December 11, 2008. The last one I can remember was about 16 years ago. The then-two-year-old Miss Divine Em was so upset by that strange meteorological phenomenon that she started to cry. (Note I didn't check the weather, so the plastic isn't even in place!)
But I guarantee that you will shed no tears over the cost of this greenhouse.