We're starting our sweet peas early this year and are hoping to plant them out as soon as possible. While I wish we had a hoop house our a greenhouse to plant them into, that just isn't in the budget for us quite yet.
Our situation got me thinking about different ways to 'hack' our low tunnels and provide the young vines with some cover during their most vulnerable state. We've only ever used low tunnels for horizontal growing space. Here is my plan to take advantage of them for sweet peas.
We'll prepare the bed as we usually would, with the appropriate amendments and some landscape fabric. Last year I used black fabric and we did fine. I might try white this year to keep the temps down - still undecided on that. Either way, there will be weed block. I manage most of the farm on my own, and I'm not giving up time to weed pulling if I don't have to. That was a lesson I had to learn the hard way.
Down the middle of the row I'm going to drive in 3-foot t-posts. (The same kind that I use to anchor the ends of the low tunnels) I'll attach a piece of 4-foot wide Hortonova trellis netting vertically along the posts with zip ties. Because the width of the netting is larger than the height of the 3-foot t-posts, I'll let the excess hang down from the top-- just kind of flop down or roll it and tie it in place with some pieces of string or clothespins. It will get pinned up when the plants grow taller. (Check back for photos of this in a moth or two if this seems confusing.)
Next, I'll put up the 4ft hoops that I bend on my own out of 10ft electrical conduit and one of Johnny's Selected Seeds hoop benders. These hoops sit on 4ft electric fence posts that I drive about half way into the ground with a fence post driver. Cover the low tunnel with plastic as you normally would and tie it down. Plant your baby sweet peas inside along the trellis and start training them up.
When danger of hard frosts have passed and the peas are ready to grow higher, I'll remove the plastic and hoops. I'll drive in and "sister" 6ft t-posts next to the 3ft posts and roll up the extra Hortonova netting. Secure the netting with zip-ties to the 6-ft posts.
When the sweet pea or other vines reach the top of the netting, add another layer of trellis netting. When they reach the top of the t-posts, extend your growing space by adding an electric fence post to the top of each 6-ft t-post. Overlap the two posts by about 4 inches and fasten them tightly together with two zip-ties. Add another layer of trellis netting if you need it. Again- zip-ties are your friends. Here is a photo of the netting going all the way up to the top of the electric fence post extenders.
This plan will allow you to scale up your growing space when you're ready - or more importantly, when your plants are ready. It will protect them from heavy spring rain, wind, frost, and even snow. For an additional layer of protection, drape a piece of Agribon frost protection fabric over the 3ft posts inside of the tunnel. The posts will "tent" the fabric and prevent it from pressing on the baby plants.