Using a Greenhouse with Aeroponics

by Connie Davis
(Robertsdale, Alabama)

I'm just starting to read and plan for my garden, but I was thinking of using a 10' x 22' greenhouse for my growing. I live in the southern part of Alabama, and we USUALLY have decent weather most of the year. Would aeroponics do well in a greenhouse, and what would the heat and air circulation and exhaust need to be?

Also, I was wondering if using 6" PVC for my system and using an outdoor misting system with a recirculating pump would work? I have a misting system I bought for using around a shed I have for summer heat, but thought it may work inside a six inch PVC pipe for the root system with holes drilled in the top for the plants.....or would I need a larger size pipe? Just thought I'd see what you thought.
Thanks, Connie

Answer: Connie- I have built many hydroponic systems out of 4 inch PVC (for cost), but really WANTED to build them out of 6 inch PVC. In my mind, 6 inch PVC is the ideal size for this type of project. 6 inch PVC provides both more drainage and more room for the roots to grow.

The idea of using the sprinkler system inside the PVC pipe should work well....similar to the 1/2 inch line in this homemade aeroponic system (as long as you have good coverage at each plant site).

Usually, clones or seedlings are placed into small, net pots and filled into place with pre-soaked clay pellets. The small net pots fit into holes cut into the top of the PVC pipe (where they will be hit by the nutrient solution spray). I describe in much more detail the system I use for cutting the plant holes while making this system here.

Most plants benefit from some air circulation, and one 12 inch oscillating fan will provide adequate air circulation for each 8 foot x 4 foot section of the garden. Your exhaust should be run primarily to keep your temperature down, but also to keep the humidity down as well. In warm weather, the vents in your greenhouse should be kept open as a primary way to help lower the heat.

A large exhaust fan should be set to kick on whenever temperatures in the greenhouse go over 75 or 80 degrees. Ideal temp is 70-75 degrees, with plants still doing well at 65-80 degrees or so. Ideal humidity is 50% plus or minus 10%. Low humidity is usually not a problem....when humidity goes over 70%, you may want to run your exhaust extra.

For a 10' x 22' greenhouse, you will want a 500-600 CFM (cubic foot/minute) fan at least. How often you exhaust will depend wholly on the temperature and humidity inside the greenhouse at the time....one very handy solution is to allow a thermostat to control your exhaust fan. Otherwise, watch your thermometer carefully and adjust your exhaust cycle manually over the next few days. You want the temp to be ideal night time as well as day.

The re-circulating pump should work fine, as long as it is strong enough to drive the sprinkler line running through the heart of your system. Keep the nutrient solution from getting too warm and maintain it properly (how to grow hydro) and it sounds like you are all set for success! I would love to hear how things turn out!