Low Tunnels For Gardening Success

I've been saying for two years that I would plant a fall garden and I finally have something in the ground! This summer when I passed through Oregon and had a chance to stop at Territorial Seed Company, I picked up some seed packets specifically for cool and cold weather crops; various of varieties of green leaf vegetables along with broccoli, cauliflower, cabbage, beets, carrots, and parsnips.

My motivation came from Eliot Coleman's book Four-Season Harvest and the supplies for my low tunnels came from Johnny's Select Seeds. Eliot writes that his inspiration came from the four season gardens of France, which he later realized were located at nearly the same latitude as his farm in Maine. At that point, it became clear to him... sunlight, not temperatures alone, were a crucial factor in growing certain crops during cooler months if coverings were used to maintain as much warmth as possible.

Eliot Coleman uses two coverings for the most part; a low row tunnel and then a high tunnel which is large enough to walk inside. The cost of the high tunnel is more than my budget could handle at this time, but the low tunnels were reasonable by comparison. However, a single row cover alone will most likely not provide enough protection during the coldest of months with the exception of a few root crops that are mulched and covered. Still, it will extend the season considerably and allow me to hopefully get a jump on the season much early next spring. Hopefully, the low tunnels alone will allow my garden to produce for at least three seasons of the year.

Low tunnel covering with bird netting secured with snap clamps.

Low tunnels can be made from a variety of materials, but most use pvc or conduit. To use pvc, just bend and slip it over rebar stakes driven in the ground. While this is certainly cost effective, it will not withstand really strong winds or heavy snow loads as well as conduit. Another consideration is the effect of sunlight; conduit will win hands down in this category.

It's probably no surprise what I chose. Living in a high wind area that experiences periodic snows accumulations of 3"-12" at a time, I decided to spend the extra money and go for durability and longer life span.


The other big investment, and I mean BIG, is your covering. These items are anything but cheap! Don't be surprised to spend as much as $100 on a 100' roll of some products. The good news is they are fairly durable and can be re-used for several season depending on weather conditions and circumstances.

Uses for Hoops:

• Bird Netting. Having a ready supply of hoops has provided support for covering seedlings with bird netting to keep the quail and other birds from eating them as they sprout. This has been a huge issue for me since I live where there are plenty of birds. In fact, it's been so bad, I haven't been able to grow one thing from seed unless it was started indoors or covered with bird netting.

• Shade Cloth. In the heat of the summer, shade cloth can proved a bit of covering to protect your lettuce and other crops from the intense sun which can make them bitter or bolt (and go to seed).  Shade cloth is easily supported by low tunnel hoops.

• Agribon. Agribon makes several different products for low tunnel covers: insect barriers, floating row covers, and regular row covers. As a light weight row cover fabric that breathes, it can provide sunlight yet protect plants from freezing by 4-6 degrees (advertisements say it can protect down to 28 degrees). This can make the difference between loosing a crop or saving it during the first part of fall when freezes are light and not so intense. It can also provide extra protection for plants later in the spring.

• Tufflite. Tufflite is a nursery grade UV resistant clear plastic cover used on greenhouses and low tunnels. It's very durable for long winters and can help keep your plants cozy. Just remember that on warm days, you'll need to raise the sides a bit to allow air to circulate and not build up excess heat and moisture.

You can see that these can quickly become a year round garden necessity and a worthy investment. I really drug my feet to spend the money on the bender and covers due to the initial cost, but now I realize that if I'm going to get serious about my garden providing food for my family most of the year, it's a small price to pay. After shelling out more money than I'd like at the grocery store for nutritionally inferior produce, I'd say this was a good acquisition.

Supplies Needed:

a jig to bend conduit or Quick Hoops Bender (4' or 6') $59
1/2" EMT conduit (3/4" conduit optional) (approx. $2.50/10' stick)
snap clamps (optional but highly recommended - love them!) $4.95/10 per pkg.
covering choice: bird netting, shade cloth, Agribon, Tufflite (price varies)

Bending Conduit:

If you're purchasing the Quick Hoops Bender from Johnny's Select Seeds, you'll need to attach it to a sturdy surface that won't move when you're bending the conduit. It comes with two very long screws that allow you to do this (and great instructions!). We used our old picnic table because it's on its way  to being replaced anyway.

Take a Sharpie and mark all the conduit exactly in the middle. Do the same to your Quick Hoops Bender. This way, you can line the mark up on the conduit and on the bender and you'll have perfectly centered hoops and none of them will be lopsided. 

Slip the conduit in the bender and extend the EMT about 16" beyond the bender. This will create a straight leg for the hoop.

Begin bending, pulling the conduit toward you. It's hard to tell in the picture, but it will fit right up against the bender between the two larger pieces of EMT as seen below...

Stop when you get to the end. Take it out, flip it around, and do the same thing to the other side of the conduit. Don't forget to realign your marks to center it!

Once you have both sides bent, stand between the ends, grasp both legs and pull toward you until they meet the bender on each end.  (Sorry the photo doesn't show this step; forgot to take that shot.)

When you're done, you'll have uniform hoops for a nice look in your garden and supports for your selected covering.

This post has been linked to Farmgirl Friday!