Saving Your Seedlings with a DIY Greenhouse

by Margie Siegal

The bird in the photos is a California Towhee. This robin-sized bird is common in the San Francisco Bay Area. It eats just about anything, but what it really likes is the seedlings you just planted. One year I lost half of my tomato starters to this #$%^& critter.

One solution to the problem of how to grow vegetables despite towhees is to put a cover of chicken wire or hardware cloth (wire mesh, available at Encinal Hardware and other hardware stores) over your starters, which will deter this little pest. This fix works for most crops, but not for peas, which seem to be especially tasty to towhees. Beans, for example, lose their charm when they get 5-7 inches high.

Covering the plants with wire or netting does not work for peas. The tendrils will latch onto chicken wire or bird netting and make it impossible to remove the cover to weed or pick the peas. I eventually came up with the idea of a greenhouse, made of ¾ “PVC pipe (which I had lying around) and covered with lightweight row cover. Row cover is non-woven cloth. It lets water and sunlight through and keeps bugs (and birds) out. Despite its light weight, it is quite sturdy. Organic farmers use row cover extensively over crops, sometimes putting wire hoops under it to keep it off lettuce and other delicate vegetables. Using it to cover a greenhouse was an experiment – which worked.

PVC pipe is lightweight and weather-proof. It will stay straight if cut into no more than 4 foot lengths. Longer pieces will sag. Using a hacksaw, I cut 12 four -foot lengths of pipe, and connected them into a cube with three-way PVC pipe connectors, available from Home Depot. Make sure you get the right size connectors for your pipe size, i. e. 3/4” connectors for 3/4” pipe. The connectors are a push fit, but tapping them into place with a mallet (or a rock) ensures that they will stay connected, despite wind and rain.

Pick up your cube and place it where you want to grow your peas. I put tomato cages in the cube as pea supports. The cages can be repurposed for tomatoes when pea season is over. The white cover over the cube is summer insect barrier from Territorial Seed Company, which I used for its excellent light transmission, but any row cover that is at least 4 feet wide will work. Now comes the tedious part: attaching the row cover to the cube on three sides. I have sail needles and sail twine, so that I what I used. Whatever you use, make sure that it is not going to come off easily. My cube has gone through three windy nights and several rainstorms at this point and is still holding up. The summer insect barrier comes in 20-foot lengths, so in order to have enough for the top flap, I put in a hardware cloth insert in the back. The mesh also provides for airflow.

Cut two more pieces of PVC pipe, 4 ½ feet long, or use a dowel or a 2×2 piece of lumber if you have run out of PVC pipe. Sew the remaining piece of row cover (which should be long enough to go over the top of the cube and down to the ground in front) into a sleeve over the pipe. Wire the pipe to the back of the top portion of the cube. Sew the other end of the row cover around the second piece of pipe or lumber. I piled bricks against the cube to stabilize it. The hardware cloth insert extends past the bottom of the cube, and bricks placed on the extension help keep the cube in one place. I used plant clips, used to attach young trees to a support, to keep the top flap in place because I had them on hand, but anything similar will work. When you want to water or weed, just unclip the top cover, pick it up and put it on top of the cube. Wire the flap on top of the cube when the peas flower to let in pollinators.

You can now plant your peas and thumb your nose at those towhees.