Dedicated readers (if there are any) may remember that last year, I put together a makeshift, greenhouse-like structure out of old fencing, some fenceposts, and some plastic tarps. Rather than go down that same path this year, I decided to build a mini-greenhouse for each of my grow tubs.
First, I built a wooden frame around the grow bed. Not as easy as it sounds, even though all the grow beds are the same product. They each seem to sag in a different way, so each of the frames had slightly different dimensions and different heights.
Next, I created a PVC greenhouse using mostly existing 1/2" PVC that I had from other experiments uses. I bought special 45 degree elbows and special 3-way fittings for the bottom corners from a greenhouse supply store.
Once the PVC frames were done, I used my old plastic that I used last year. I basically rolled the frame in the plastic, then used plastic clips to hold the clear/opaque plastic to the PVC frame. Each greenhouse has 2 little chimneys that I'm hoping will help it from getting too hot in there. Though the plastic drapes down the sides, it's certainly not air tight, so there should be some air flow, even when the sides are fully down.
Here's a view through all 3 greenhouses. I rolled up the sides to keep air moving through there. I probably will keep it rolled up until it gets closer to 25 degrees at night.
The cilantro, arugula, and spinach that I've planted, along with the tub full of strawberry plants, proved last year that they can handle the cold. The greenhouses should help warm things up during the day nicely, and they'll keep the frost off of the plants at night. Another side benefit is that they keep the leaves from landing on the grow beds! This time of year, it's a daily chore picking the leaves out.
I put in another order for rainbow trout this year. It went so well last year, I figured we'd do it again this year!