Plastics in the Garden

Learn how to customize a plastic greenhouse for less than $20.

From the milk jug to the computer, plastics are an integral part of our lives. This renewable, reusable, reliable and recyclable garden material can work for you in your yard. Plastic resists water, weather and pest damage; is low maintenance, lightweight and long-lasting; and has a million uses to boot.

Figure A

"This Adirondack chair is made with 240 milk jugs that otherwise would have gone to the landfill," says plastic packaging engineer Joyce Gagnon. By recycling plastic products, you give life to something that is no longer of use. "Look at it — it looks weathered, it looks like wood, it's beautiful, and isn't that what gardening is all about?"

Figure B

This plastic compost bin also makes use of discarded materials by recycling old yard and kitchen waste into a soil enhancer. Composting needs three conditions: moisture, air circulation and heat. Plastic helps contain heat and moisture.

Figure C

This homemade plastic wind break protects the crops underneath from strong winds, but as fall gives way to winter, a sturdier cover that will withstand the harsh environment, such as a greenhouse, is much more effective. Joyce demonstrates how to make a greenhouse that's easy to move or remove as needed.

Figure D

The frame of the greenhouse is constructed from PVC pipes that you can get at any home improvement store. Most pipes are available in standard 10-foot lengths, so for this 20- by 5-foot structure, calculations are a breeze. Another great thing about using PVC piping is that it comes with these little adapting pieces.

Figure F

Joyce lays out the pipes and connectors according to her dimensions. Next, she measures and marks the pipes. The five-foot width means she'll need to do some cutting, which is easy with a coping saw. "You can also use saws made for PVC," she says, "but I like this one. It's smaller, really easy to handle, and inexpensive."

Figure G

Working vertically, Joyce creates an arch using a 10-foot PVC section at each end of the greenhouse, and then another for the center section. She attaches the PVC segments together with the connector pieces.

To cover the greenhouse, Joyce uses a sheet of 4-millimeter plastic. "You can use it in construction or as a drop cloth when you're painting. But in this case, we're going to use it to keep our lettuce and some of our herbs a little bit warmer and still let some light come through," she says.

Figure I

With a little help from her neighbor, Joyce drapes the plastic over the PVC arches. She uses two pieces that overlap in the middle to serve as an entryway. To secure the plastic cover in place, she uses plastic cable ties. In the time it takes her to fasten all the ties, condensation has already started forming in the greenhouse. It's humid, warm and bright inside the greenhouse, exactly what the tender crops need. Another plus is that this structure will last a good, long time.

"One of the things about plastic is that it is inert to water," explains Joyce, "so it's not going to rot, and bugs don't eat it, so we have that longevity thing that we're really looking for." Even the very pliable PVC, which is a little photosensitive, will last far longer than a lot of other materials.

Figure K

PVC also makes a great watering tool for deep-root watering. Joyce hammers a 10- to 12-foot length of pipe into the ground near the root ball of a newly planted tree, leaving about four inches of pipe above the ground. The pipe directs water deep into the ground where the roots grow.