It appears you do not have Javascript enabled in your browser. Javascript must be enabled for our website to display and function properly.
Free Seeds On Online Orders Over $50

How to Build a Low Tunnel to Protect Plants from Frost

By on February 21, 2013

We’re always talking about extending your growing season with floating row covers, low tunnels, and hoop houses. These all protect your plants from frost.

Today we’ll give you easy instructions on how to build a low tunnel with PVC pipe and floating row cover.

First, watch Tricia build a low tunnel (also called a low hoop house) over one of her raised beds.

Quick review of floating row cover for frost protection

Row covers are made of lightweight fabrics (that “float” on the top of your crops) and they allow sunlight, air, and water to pass through to your plants.

Use our guidelines to choose the row cover weight you need in your climate.

Low tunnels of floating row cover give easy access to your crops, while protecting your plants from frost

Make gardening simpler for yourself when you stretch row cover over semicircular hoops to make low tunnels.

The support of the hoops keeps snowy row cover weight off your plants, and allows you to quickly lift the row cover for harvesting.

How to build the frame of a low hoop tunnel for a bed 3-5 feet wide

SUPPLIES

Per each five feet of tunnel:

2 18” pieces of 1/2” rebar

1 7 ft. length of 3/4” PVC

Pound the rebar into the ground with an angle of 35-45° toward the center of the bed. Leave about 6” of rebar sticking out of the ground. If you plan to leave the rebar in the ground after you remove the low tunnel in the summer you might want to paint the tops a bright color or flag them so they aren’t a tripping hazard.

Slide a 7-foot length of PVC over the rebar to create a hoop, repeating down the bed every 5 feet.

How to fit floating row cover over a low tunnel frame

SUPPLIES

1 piece 83” width x 50’ long AG-30 Agribon (4’ extra for each end)

1 piece of 3/4” PVC pipe the same length as your bed

Per each five feet of tunnel:

2 3/4” rowcover clamps

SLEEVE

Cut a piece of Agribon off of the roll about 8 feet longer then the length of the bed. That allows the fabric to drape over and close at each end of the tunnel.

To make it easy to vent the tunnel and harvest the crops, sew a simple “sleeve” down one long side of the Agribon: take 6 inches of the fabric along the long edge, fold it over, and stitch it in place.

Drape the Agribon over the hoops.

Slide your long piece of PVC down the sleeve. If you did not sew a sleeve, use more 3/4” clamps to secure the long piece of PVC to the edge of the Agribon.

Gather and secure the fabric at the each end of the tunnel with a rock, or a sand bag.

Now you can easily lift one side to vent the tunnel or to harvest delicious winter veggies.

When to plant in your low tunnel

Use the low tunnel to extend your seasons (See? We told you we’d say that.) at both ends of the year.

Plant cool-season crops in late summer and see how long you can harvest through the winter. Use the low tunnels to warm the soil in late winter or early spring and get a jump on growing the cool-season vegetables that prefer spring and fall.

Check out our article on cool-season vegetables to get ideas on what to plant—starting with the 10 seed packs in our Frost Kissed Gift Seed Tin Collection.

For making larger hoop houses, get all the details from renowned Maine farmer Eliot Coleman in Four-Season Harvest.

Protect your plants from frost with low tunnels, and enjoy your home harvest for extra months every year!

  Comments (30)

E

I don’t see a button for a print version of this article.  I’d want to take it to the store to select the items needed to create the hoop house.

Posted by Edith Lueke on Feb. 23, 2013 at 7:22:41 PM

S

I’m using the same idea, but I’m using galvanized steel support hoops I ordered a few years ago from Gardener’s Supply…there’s no assembly involved, you just take 2 super hoop sections, connect them w. the included couplers, and stick them in your soil, and add your cover.  Pretty easy, can’t complain.  (Also, they don’t splinter like PVC does after several seasons out in the elements.  I do want to thank you for these terrific and informative videos, they’re my “go-to” resource for anything garden-related.  Plus, everything I’ve seen here is environmentally sound, so far, that’s probably why I love visiting Peaceful Valleyddle….!

Posted by Sabine Williams on Feb. 24, 2013 at 6:02:19 AM

Edith, We don’t have a print button for the articles because they contain so many photos. Here’s a list of supplies you can copy and paste and print. Also, the store staff know all about this and can assist you, without a list. Have fun with your low tunnel!

Per each five feet of tunnel:
2 18” pieces of 1/2” rebar
1 7 ft. length of 3/4” PVC
2 3/4” rowcover clamps
1 piece 83” width x 50’ long AG-30 Agribon (4’ extra for each end)
1 piece of 3/4” PVC pipe the same length as your bed

Posted by GrowOrganic.com on Feb. 24, 2013 at 7:53:29 AM

Sabine, Glad to hear you find our video series useful! Sounds like your hoops are working well for you. Just to let you know, if you want to add more low tunnels, we do carry galvanized steel support hoops in 2 styles, with no assembly required:  http://www.groworganic.com/loop-hoops-each.html and http://www.groworganic.com/maas-wire-for-hoops-10-pk.html

Posted by GrowOrganic.com on Feb. 24, 2013 at 8:02:04 AM

G

If you splice in “T” connectors about 8” - 12” below the hoop apex,  you can rest the “vent” piece in the sleeve on them allowing better access and leaving your hands free to work.

Posted by George on Feb. 27, 2013 at 1:34:47 AM

George, Thanks for the great tip!

Posted by GrowOrganic.com on Feb. 27, 2013 at 8:33:47 AM

M

The 3/4 pvc seems really hard to bend.  Did anyone else have difficulty?

Posted by Mardi Naythons on Feb. 27, 2013 at 11:35:43 AM

C

Mardi,

Assuming that you are working with new PVC: Don’t be afraid of it. Put it in the sun on a warm day and as it heats up it will be easier to bend. Don’t worry that it will snap when you bend it.

If you are dealing with older PVC that has been outdoors for a few seasons, then do exercise caution, as that might snap.

We hope these tips are helpful!

Posted by Charlotte, Peaceful Valley on Feb. 28, 2013 at 4:22:09 PM

D

I built similar hoop structures over my carrots a couple of years ago using surplus flexible black water pipe that I found in a shed. The black pipe comes in a roll so it already curves and is sturdy enough. I added a ridgepole using 1/2-inch 10-ft length of PVC pipe, connecting it to the hoops with zip ties. It worked great and I kept the floating row cover on the carrots all season, yielding a bumper crop with no pest problems. The sleeve idea sounds great—I will try that. I had to “pad” the ends of ridgepole so they didn’t poke holes in the FRC.

Posted by Diane Murray on Mar. 02, 2013 at 7:51:21 PM

Diane, What a great idea to use the water pipe! Thanks for sharing that here!

Posted by GrowOrganic.com on Mar. 04, 2013 at 12:35:54 PM

R

But isn’t PVC toxic?

Posted by Regina ludus on Mar. 27, 2013 at 7:40:07 PM

Regina, The staff here use PVC as hoop supports in our organic gardens. We also offer metal Loop Hoops and Wire For Hoops, if you prefer to avoid PVC http://www.groworganic.com/growing-supplies/shade-fabric.html

Posted by GrowOrganic.com on Mar. 28, 2013 at 10:56:41 AM

G

PVC in bulk comes in 10’ and 20’ lengths.

Any reason I couldn’t get away with using 20’ lengths cut into thirds (at 80” just a bit shorter than the 7’ lengths suggested for the hoops)? This seems like it would be a slightly better match for the 83” Agribon, particularly if the Agribon is seamed on the edges.

Posted by Gary Gapinski on Apr. 15, 2013 at 1:56:22 AM

Gary, That sounds just fine!

Posted by GrowOrganic.com on Apr. 15, 2013 at 11:51:40 AM

J

Can this fabric be left over plants during the day if the temperature is not too low?

Posted by Jamie on Jul. 25, 2013 at 3:53:45 PM

Jamie, Certainly you can leave row cover on all day, especially if the temperature IS low. Some farmers and gardeners use the lightest weight row cover all spring and summer as a barrier to pests. Once you have your frame built you can change weights of row cover depending on the season and your needs. Here is our guide that explains the different weights of row covers, and their uses http://groworganic.com/organic-gardening/articles/find-the-right-floating-row-cover-for-plant-protection

Posted by GrowOrganic.com on Jul. 30, 2013 at 3:52:27 PM

J

I use 5 foot pvc pipes for uprights and pex pipe

Posted by Joe on Oct. 21, 2013 at 1:36:37 PM

S

I have been searching online for how to care for my garden in a hoop garden, but there isn’t anything that tells me. I want to know if I can leave it on all year round (California) and how often do I water. Can anyone help me please?

Posted by Shelly on Mar. 07, 2014 at 4:09:23 PM

Hello Shelly,
If you’re using a floating row cover like Agribon than it can be left on all year on greens and root vegetables as an insect barrier. If you do that than switch it to a lighter cover like AG-19 in the summer when you don’t need the frost protection so you are losing less light. If it’s a vegetable like squash that needs to be pollinated then the covers need to come off when it blooms so the pollinating insects can get in. Water it like you would any other garden, drip is the easiest to use under the cover. Let me know if you have more questions and I’ll try to get answers for you.

Posted by GrowOrganic.com on Mar. 10, 2014 at 10:08:13 AM

D

I did a really, really low cost version of “hoops” - I put old 2 liter bottles upside down in the ground between my plants! When they come out I’m cutting the bottoms off to start slowly stacking them to build walls for a greenhouse. Working great so far though one night strong winds blew some of the bottles down. I have 2 questions: 1) I’m remodeling our back yard lawn into a garden park look so I’ve just been trenching rows for vegetables with grass in between and still using lawn sprinklers for watering. The water seems to roll off to some extent (I expect that happens to hoops too) so how can I determine if plants are getting enough water ? 2) I’m doing this with broccoli cabbage and cauliflower, which birds and insects really ate up last year at least until they got larger. Is pollination by insects an issue for these brassicas?

Posted by Dave on Apr. 16, 2014 at 6:39:26 PM

Hello Dave,

Put a finger in the soil after water and see if they are getting moisture. Also make sure the plants aren’t wilting. As for the birds and insects, brassicae don’t need pollination since you’re eating the flower buds or the leaves not the fruit or seeds. You can use a light rowcover like Agribon Ag-19 to protect them from birds and bugs.

Posted by GrowOrganic.com on Apr. 21, 2014 at 10:24:30 AM

B

Charlotte,
Will this keep crows off of my newly seeded corn?  I am now on my third planting and have a chicken wire “hoop” over the new corn.  If this works it wold be a lot easier to handle.

Thanks,

Bill

Posted by Bill on Jul. 24, 2014 at 10:19:40 AM

The tunnels will work great just use a lighter weight rowcover more suited to pest protection like the Agribon-19. It is lightweight enough to just lay on top of the new seedlings.

Posted by Suzanne at Peaceful Valley on Jul. 25, 2014 at 12:14:44 PM

J

Why not use 1/2” pvc or grey conduit?  Is there a benefit to 3/4”?  Both will fit over the rebar.  Thanks.

Posted by Jesse on Dec. 09, 2014 at 2:38:45 PM

You can use 1/2” PVC, it is just not as strong as the 3/4”. I am not sure how flexible the grey conduit is. Will it bend as easily as the white PVC.

Posted by Suzanne at Peaceful Valley on Dec. 10, 2014 at 3:26:50 PM

D

Where can I find a pattern for a hoop cover that goes over a small raised bed garden, that you can slide back and forth to cover and uncover your plants. I have seen the one that you use pvc pipe and rebar, but you have to cover and uncover the plants manually.

Posted by Debbie on Jan. 26, 2015 at 10:48:54 AM

The only covers that I have seen are for really big hoophouses. I would just try a search on the internet to see what you can find. You might also think about using a different type of greenhouse plastic that will breath so you would not have to cover and uncover. It is call Diobetalon and here is a blog with more information, http://www.groworganic.com/organic-gardening/articles/row-covers-extend-your-growing-season-with-dio-betalon. The covering allows the plants to “breath” during the day but keeps them warm at night. Check it out.

Posted by Suzanne at Peaceful Valley on Feb. 06, 2015 at 9:11:11 AM

H

What is the grad of the PVC pipe; Class180, Class 200 or Schedule 40?

Posted by Herb on Apr. 13, 2015 at 11:56:30 AM

The pvc is schedule 40, once a little warm, bends quite easily.

Posted by Suzanne at Peaceful Valley on Apr. 13, 2015 at 2:22:42 PM

M

Thanks for the great ideas. I now have 3 of these filled with healthy plants. One improvement I made was to sew an 8’ pocket down the length of each side. Insert a 1/2” plastic rod into the pocket. the weight of the rod keeps the sides closed. I use cloth pins to help fasten the loose corners.

Posted by Marie on Jun. 19, 2016 at 6:10:56 AM

+ Show More Comments

Leave a Comment