How Add A Tunnel To Raised Garden Bed

Weather: Cloudy with scattered showers; High 66°F, Low 44°F

Guess what? We are going to try winter gardening! This will be a new adventure for us and we are excited to embark on this experiment with you. We have installed several low tunnels on raised beds to extend the growing season and try for year round gardening. With this low tunnel design, our garden beds will be 3-4°F warmer than the outside temperature. We are adding tunnels to beds growing fall crops planted in September and in beds that have been cleared and will be planted with seeds throughout the winter from our fall seed package. If you are interested in adding a tunnel to garden beds at your school please don't hesitate to contact us!

Step 1: Gather your materials. After a few test trials, we decided upon the following list of necessary materials (this list is enough for one 4'x8'x1′ garden bed). Click on the links for vendors:

5 PVC poles 7′ 4″ in length (purchase 10′ and cut 32″ off one end-there are lots of projects you can complete with the extra pieces; click here for ideas)
16 pipe straps
36 wood screws & matching drill bit (included in package)
12 feet of Agribon 19 row cover
10 bricks
PVC cutter
8′ tape measure
Permanent marker
High powered drill
Seeds for cool season crops

Step 2: Mark the raised bed.Using a tape measure mark the bed at the following intervals: 4", 32", 62" and 92". Do this on both sides of the raised bed. Measuring and marking is one of the jobs students can work together to complete.

Step 3: Screw in the pipe straps.At each mark on the raised bed two pipe straps will be screwed in. Screw one in an inch from the top of the bed and another directly below the top pipe strap and six inches from the top of the bed. Screw in all pipe straps on both sides of the bed (16 total). The two pipe straps must line up or the PVC poles will not slide into them.

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Step 4: Mark the PVC poles.Using the permanent marker, mark 8" in from one end of the PVC pole (this mark will line up with the top of the raised bed), another at 44″ (this will be the highest part of the hoop), and a final at 80″ (this mark will line up with the top of the raised bed). If you purchased 10′ poles you can cut it at 88″ so the pole is 7′ 4″ in length.

Step 5: Attach the PVC poles to the bed.Slide the PVC pole into both pipe straps on one side of the bed, then bend the pole to the other side of the bed and insert it into the pipe straps on the opposite side. Slide the pole down so the 8″ and 80″ marks line up with the top of the bed. The 44″ inch mark should be the highest point of the bend in the PVC pole.

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Step 6: Add the stabilizing PVC pole (optional). Place your final PVC pole along with length of the bed. Mark the pole at each point where it touches the PVC hoops that are secured on the bed. This should be every 29″. At each mark drill a screw through the first layer of PVC-don't go all the way through the pipe. After all four screws are secured cut the PVC at each end so there is as little as possible sticking out. This will reduce the possibility of having the row cover (attached in next step) get snagged and tear. Have students hold the trimmed PVC pole with the screws facing up so an adult can complete the drilling of the screws into the center of the hoops from the underside (at the 44″ mark made in step three).

Step 7: Anchor the row cover.The row cover we suggest in step one above reaches the ground on both sides of the width of the bed when centered. It's very important to be able to be able to anchor the row cover on all sides of the bed, so before cutting make sure to test you have the right length! Anchor with bricks so it is secured on all sides.

Wahoo! You've just installed a low tunnel on your raised bed! Check on your garden at least once a week, continue succession planting and harvesting greens. You may need to water the bed more often since it will be warm under the cover. On warm clear days you can remove the cover but be sure to put it back before the cold nights.

There are many options for extending the garden season. No matter what method you choose, we'd love to hear from you and offer our support and encouragement! Please contact us at youtheducation@civicgardencenter.org with questions, comments and ideas!