moles & greenhouse and cold frame construction

Asked August 17, 2014, 5:36 PM EDT

I'm building a small greenhouse and cold frame in the Colestine Valley ( just 2 miles from Hilt) and request your expertise. I see lots of ground squirrels in the area and am not sure if they (or voles or moles) will be a problem. Is it advisable to place wire-mesh bottoms in the cold frame and greenhouse? And what about the sides? The greenhouse and cold frame will be built along the wall of an existing cabin; is it safe to assume that rodents won't gain entrance from that side? I thank you in advance for any help you might offer. Rebecca

Jackson County Oregon

1 Response

Thanks for using Ask an Expert, Rebecca. There are several issues in your question. Let's deal with rodent problems first. Yes, ground squirrels are capable of tunneling under foundations if there is a reason for them to get inside: shelter or food. Keeping any attractants such as birdseed, fish meal, pet food, etc. stored in tight containers should relieve that incentive. I have personal experience with a solar lean-to style greenhouse attached to a garden shed. Both greenhouse and shed are constructed on top of a concrete block foundation. Crushed 3/4 minus rock fills the floor of the greenhouse; there is no screening. In almost 20 years, I have never had a ground squirrel attempt to breach the foundation of either building. Gophers and moles are discouraged by the block and the gravel. Screening the bottom of your coldframe is practical only if you are not going to plant directly into the soil at the bottom .Voles and House mice are above ground travelers; they will be a nuisance if the door is left open or there are other open entries. Be sure to screen any vents, windows and fill any spaces created by inserting fans, etc. into the sides of the greenhouse. None of these rodents is a protected species at this time, so if elimination is required, trapping, shooting, and poisoning are all legal. However, there are dangers to friendly wildlife with all of these methods, so exclusion is the best course of action. We'd like to recommend you check out the following pamphlets available from
FS246E: Constructing Coldframes and Hotbeds
PNW 497: Short-Season Vegetable Gardening
EC1579: Living with Nuisance Wildlife
EC1429: Controlling Ground Squirrel Damage..
The following books are recommended:
Greenhouse Gardener's companion by Shane Smith, Fulcrum Pub.1992
Gardening Under Cover: A Northwest Guide to Solar Greenhouses, Coldframes, and Cloches by William Head, Sasquatch Books, 1989. Good luck with your asdventure into greenhouse gardening!