Saturday, February 23, 2013

How To Make Row Cover Frames for an Existing Raised Bed

I'm asked every day at work how to make frames to hold up row cover, so I thought I'd make a separate post about it.  This is the last part of the Building a Raised Bed From Existing Soil: Illustrated post with a few more details and ideas added.

Frost bitten kale. Kinda' pretty when it's all  frozen and
sparkly.  Not so much when it's all thawed and droopy.
For those who don't know, floating row cover (aka Remay or frost cloth) is a lightweight cloth specially made for covering plants during winter for frost protection.  There are lightweight types that are used as a pest barrier, but for this post we'll be talking mostly about the heavyweight type.  The heavyweight that we sell at the Natural Gardener makes the temperature under the cloth eight to ten degrees warmer than the ambient temperature outside, while allowing rain and plenty of sunlight for actual plant growth to come in.  Due to those last two things along with the fact that it lets excess heat out, you don't need to take it off and put it on again every day like you would plastic.  Handy!

It's great stuff and I highly recommend it for covering newly planted things in a light freeze, most everything in a hard freeze, and newly planted seeds no matter the temperatures (it keeps the wind from drying out the soil so fast and beating up your new babies).  I've even been able to keep warm season things going through the first few freezes of the year (Ahhhhh, Christmas tomatoes...).

Speaking of tomatoes, this row cover is essential in getting those tomatoes in extra early to beat the heat.  I've even had success planting them as early as Valentine's Day if I hung some incandescent Christmas lights on the cages under the cover.  I leave them covered from planting to the end of March or early April, rarely if ever taking it off, and the combo of incandescent lights giving off heat and the cover holding it in makes it nice and toasty under there, warm enough for the plants to actively grow, even on forty degree days.  No, 40 degrees won't kill your tomatoes, but it'll sure make 'em pout.

The row cover works by trapping the Earth's heat radiating up at night, creating an insulating air space around your plants, a sort of warm-air "bubble" like a miniature greenhouse.  And just like a real greenhouse, the sides are as cold as the outside, so any leaves touching the cloth (or the plastic in a greenhouse) will be susceptible to freeze damage.  

Hence the frames.  They're not that hard to build.  Really!  They're cheap, easy (don't even need any power tools), and they last for years.  Come to think of it, you don't need any tools at all if you're handy at hammering with a rock.  Ha!

Here's the step-by-step:


Materials for a 4'x8' bed with approximate costs including tax (Note: My beds are 12' long, so the pictures show 8 rebar stakes and 4 pvc pipe ribs.):
  • Six 3/8" thick rebar stakes, 18 inches long .......................... $11
  • Three 10' lengths of 1/2" schedule 40 pvc pipe ................... $6
  • Row Cover: 18' heavy duty ...................................................$25
  • Six heavy duty clamps OR large binder clips ........................$20

  • Total for frames only ........................................................................... $17
  • Total for frames, cover, and clamps...................................................... $62

Photo 1
1. Install rebar stakes at all four corners (Photos 1 and 2).  Just pound them in with a hammer.  3/8" thick 18" long rebar stakes are about about a buck fifty each at Lowe's.  Ones 18" long will go at least nine inches into the soil below the box and still have three or so inches sticking up above the box for the pvc to easily slip over.  I used some 18" long ones since I had them already, but when I bought more I got 24" long ones since they were only twenty or so cents more, but would go farther into the soil, making them even more sturdy, especially if the beds are tall.

Photo 2
If your box is bigger than 4' x 4', you should put some stakes along the sides as well.  My beds here are twelve feet long, so I installed them every four feet.  For an eight foot bed, that would be three on each long side.  If you want to install them closer together, that's great ~ the closer they are, the more ribs of your frame you will have, and the stronger the overall system will be once you cover it with the row cover.

6. Install the pvc pipe by simply slipping it over the rebar stakes, as in Photos 3, 4 and 5.  I used 1/2-inch pvc, ten feet long.  This gave me 4' tall frames, perfect for covering even the tallest broccoli plants and most shorter green peas even when on a pea fence.

Photo 3
7. Cover the frame with floating row cover and clip into place (Photo 6).  Row cover usually comes on a roll and is sold by the foot from that row.  The size we sell at the Natural Gardener is 12' wide (plenty for covering the width of your bed, across those pvc ribs), and the length needs to be the length of your bed plus ten feet to allow it to hang down over the ends and cover them well.

You can use any kind of clip so long as it's STRONG.  I bought some of all the clips I found at Lowe's when I bought my stakes.  You can see the black ones in some of the pictures, and here's a better picture of them.  They're great for the corners as they can open up wide to grab a lot of bunched row cover in their "mouths".  The bad part is they're kind of expensive at $14 for a set of twelve in various sizes, some of which I don't need. 

Photo 4

You may also be able to see the big binder clips along the sides of the covered beds in Photo 6.  You can get them from an office supply store and they're fairly cheap.  Drawbacks are they aren't as strong as other clips and they rust, but if you have a lot of beds to cover like me, they're a more economical alternative at least along the sides.  So far, they've held in 15 mph winds (Update: They held in those hellacious winds we had not long ago, gusts way past 40mph with a 65mph gust clocked in Burnet, but I only used them on the sides ~ used the big black ones on the corners. And a caution: a row cover next to that one that had some holes in it was shredded, so patch your holes! Duct tape maybe.).  I don't think the binder clips would work at the corners since they'd  have to clamp over multiple layers of the row cover, but along the sides where they just have to clamp over one layer, they work great.

Photo 5
I've also had people tell me they used three-inch sections of pvc pipe, the same size as the ribs, that they've cut along one side lengthwise.  They just open the cut side enough to slip it over the pvc pipe rib, sandwiching the row cover in between.  I haven't tried this yet, but plan to, and I hope it works as that would be OH so cheap.

That's really all there is to it!  Easey-peasey..  And they'll last for at least five years, including the row cover if you keep it folded and put up when not in use.  Speaking of that, if you ever need to wash it, you can put it in the washer, but don't put it in the dryer.  It melts into nothing.  Weird.

These frames are great for row cover, bird netting and shade cloth as well, so you'd be able to use them year 'round.  You can even use the lightweight row cover for pest protection, or if you're a seed saver the lightweight works great for isolation, too.  The tomatoes will likely get too tall to still fit under them and some peppers may also, as well as corn and okra, but you could still use more pvc to make taller frames.  Investigate the pvc pipe fittings aisle for elbows to make something that looks the shape of a roofline instead of the curve shown in the pictures here (three elbows ~ one on each side and one in the middle-top).  You might could find twenty foot sections of the same diameter pvc and bend them into taller hoops, though I haven't tried that yet.  If anyone does, let me know how it works in the comments here, would you?  And if I try it, I'll update this post.

Again, they're cheap, easy, and useful.  What's not to love?  Do it!  You'll be SO glad you did.  

Photo 6

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