It Floats!

One of the best insect-protection methods I’ve used on my small farm–one that is reusable and does not require the spreading of chemicals or poisons–is floating row cover (FRC).  It’s a spun poly “blanket” that is draped over a crop and anchored at the edges by soil, timbers, rocks, or landscape staples.

For years I knew about it and didn’t use it.  Once I started using it, I wondered why I’d waited so long to try it.  Basically, it’s a barrier method for preventing insects from gaining access to the crop, but it has a number of other functions as well.

Not only does it prevent pests from feasting on the crop and spreading disease (it also keeps rabbits and usually deer from munching on tender young plants), it provides a few degrees of frost protection/temperature moderation.

It also keeps the soils from getting crusted by heavy rains (and prevents soil splash–leafy crops grown under FRC are consistently cleaner), keeps plants from getting whipped by strong winds, and provides a nice “germination blanket” for surface-sown/slow germinating crops.

While you obviously must remove row cover for weeding or harvesting purposes (I often just pull back one side or end of the cover at a time), you can water a crop right through the cover if you don’t have drip irrigation in place.  Depending on the weight of the cover, you’ll still get reasonably good airflow and light transmission to the crop.

Weeding row-covered salad mix

I used to buy FRC from a certain company that sent me those coupon catalogs for a certain amount free if I bought a certain amount of product.  But the last time I ordered from them, I realized they’d stopped carrying the heavy-duty professional strength row covers and switched to something cheaper and lighter.

From the image below, you can see what happens to cheap, lightweight row cover after only a year or two in the extremes of the South Dakota climate.  It’s not pretty.

Shoddy row cover

The best row cover I’ve found is Agribon brand.  It comes in a variety of weights–from the very light “insect barrier” version to the heavy “frost blanket” model.  I use the medium-weight AG+ 19, which gives a small degree of frost protection–even though most crops I sow under it don’t necessarily need the temperature moderation.

I have a few lengths of AG+ 19 that have been serving me for five years.  They’re a little rust-stained from having been watered with our iron-rich well water, but they’re still intact.

Occasionally one gets a bad tear from a deer hoof or a wicked windstorm, but often times I’ll simply cut out the bad part and use the smaller sections for shorter beds or individual plants.  Or, I’ll donate them to home gardener friends so they can try it out.

I anchor my row cover with 6″ landscape staples driven into the ground through a folded-over section of the cover along the edges, with the main series of staples directly opposite from each other across the bed I’m covering.  Because of their ability to “bond” with the soil as they rust, I prefer the non-galvanized staples.

Which reminds me, have you updated your tetanus shot recently?

Securing the cover

Of course, puncturing the cover can lead to fraying or tearing along the edges–you can get row cover clips that snap onto the edge of the cover and then thread through the staples, but if you just use enough staples and make sure to fold under the edges of the cover (so you’re securing through two layers of fabric), you won’t have as much of a problem.

I’ve always figured the clips were just one more expense for a plastic thing that looks fairly easy to break or lose. It also looks to me that the gap between the cover, clip, and staple would be a good entry point for bugs or damaging winds.

I have a lot fewer issues with tearing when I make sure to anchor the cover well–a staple every few feet.  If you have a “windy side” (no jokes, please), anchor it better there.

Shelterbelts protect us from the north winds in most of the gardens, but south winds come up through the river valley, so once I’m done placing the main staples across from each other on both sides of the bed, I put a few more in on that windier south side.

And speaking of wind–I know it’s hard to find a calm day in a state like South Dakota, but unless you want a wrestling match, don’t try to lay row cover on a windy day–especially by yourself.

The reason it’s called floating row cover is that it’s lightweight–it “floats” over the top of the crop–and it also floats, and twists, and gets caught on things and can rip, in even a smallish breeze.  Knowing how fast a wind can come up, I try to keep a pile of rocks nearby for anchoring while I’m getting the cover in place over the bed.

Another nice feature of the Agribon covers is that they have the brand name printed right down the center of the cover.  That makes it easier to center the cover over the bed, so you don’t get halfway down the row in the fastening process and realize it’s all askew.

Centering the cover on the row

Row cover comes in a few different widths, and you can cut it to whatever length you need with a pair of scissors or a sharp knife.  I’ve been buying 55′ and 100′ folded lengths of 60″ wide cover for years, but this year I bought a 250′ long and 83″ wide roll.

The roll is awesome for laying it out initially because you can just roll out the length you need and only have to anchor one end as you go.  Of course, when I go to re-use it, I’ll be back in the place I’ve been all along with the folded sections and fly-away ends.

The wider size is nice, too, for being able to cover wider rows or taller/wider plants like cabbages.  You want row cover to be “blousy” over the crop in order to give plants room to grow underneath without their leaves being squashed.

Rolling out the cover

I intend to implement a plan this season that will save me a lot of the row cover headaches I’ve been dealing with for years.  I’m going to write the width and length of the sections of FRC right on the ends of the fabric when I remove them from the crop, take out the staples, and put them up for the season.

I can’t tell you how many times I’ve pulled out sections of cover from the shed, unrolled them, and then found they were too short for the bed I wanted to cover. Cue swearing, re-rolling, and then trying to compare the weight and bulk of the cover that didn’t work with some others I have rolled and crammed in a crate or box.

And the difference, of course, is only a few ounces, so most of the time my comparisons aren’t very helpful.  I just have to take out another section and try it.  And the covers are usually dusty, the wind is blowing, they’re winding all around my legs, and I get frustrated as hell.

Why I have not marked the covers before is completely beyond me.  I suggest if you try row covers, you save yourself this kind of completely unnecessary frustration and mark them the first year.  Or even simply indicate the part of the garden they fit, if you have different-sized beds in different areas.

So, what crops can you use floating row cover on?

I use it heavily for the brassicas that would otherwise be shotgun-holed from the depredations of flea beetles early in the season–arugula, turnips, Asian greens, broccoli raab (unfortunately, my new FRC order came late this year, so some early crops are damaged).

It’s useful to keep cabbage moths and loopers off cabbages, and I occasionally put it over broccoli as well (I use diatomaceous earth as a back-up method).

Floating row cover is also nice to keep the soil moist for surface-sown lettuce and salad mix and slow-germinating carrots, and to keep rabbits away from tender young beets and chard (though it does tend to mash chard leaf tips down a bit once they start getting tall).

I also occasionally use it for fruiting crops early in the season–it must be removed in order for pollination to occur, but I’ve had good luck planting squash and cukes underneath row covers until they’re big and strong enough to face the world bare and unprotected.

In fact, the middle of the brassica row pictured in the images will be sown with summer squash once the weather warms sufficiently.

The odor of the broccoli raab and bok choy “stumps” decomposing under the cover will hopefully camouflage the scent of the young squash plants and ward off cucumber and squash beetles during its early development stages.  This strategy seemed to work with decomposing cabbage stumps and young cucumber plants last year, so I’ll try it again.

The cover has to come off once the plants start blooming, but by then, they’ll be strong enough to shrug off a few nibbles, and I can keep an eye out for insect egg clusters under the leaves.

I’ve used row cover once or twice for peppers and tomatoes transplanted early, but I’ve only ever done this with a support mechanism like wire cages (which, if they have rough edges, tend to tear the cover–be forewarned).

Plants with a tender growing tip don’t like it abraded even by the light weight of the fabric moving in the wind.  Plants that need wind-pollination (like corn) shouldn’t be covered, either.

Safe and secure under the blanket

As I’ve mentioned before, the main idea with FRC is the “floating” part–let your cover be “blousy” over the crop to give it room to grow.  Because of the blousiness, the ends of the covers tend to have some puffy, open areas.  As you can see, I put a landscape staple in the middle and on the sides, and then a couple rocks to weigh down the gathers.

If you want even better insect protection, you can pile up soil (or even lay pipe or lumber) along the edges of the cover to “seal” it.  Whether or not you use this method depends mostly on how much pipe or lumber you want lying around your garden or how often you want to have to remove and re-mound the soil when weeding and harvesting.

Because I like to check on my crops often, and because I don’t have a lot of lumber hanging around, I don’t do either of these things, so I still have small occasional insect depredations–but very little compared to an uncovered crop.

It is important to check a row-covered crop occasionally anyhow–just to make sure you haven’t sealed in any pests that are now happily munching away, safe from their predators.  I’ve had to uncover an aphid-infested row of turnips, but the ladybugs that had been excluded by the FRC then moved in fast to clean up that problem for me.

So, please don’t think of floating row cover as a completely fail-safe solution for pest control, but also don’t wait as long as I did to try this reusable barrier method that has so many other benefits.

Bugs can’t develop immunity to it, as they can to some kinds of pesticide sprays, and the cost of FRC is lower over time if you anchor well and take reasonable care to avoid tears.


4 responses to this post.

  1. Posted by Mary on May 10, 2010 at 12:31 pm

    Hi Rebecca: I put floating row covers (aka frost blankets) on my plants a couple of days ago. But my son is afraid of how the plants are getting whacked around by the wind. He feels that the weight of the moisture that remains on the surface and the wind combined are bending the plants over. Do you see this as a problem? If so, what can we do about it?


  2. Posted by flyingtomato on May 10, 2010 at 7:04 pm


    It depends on a few factors–the weight/gauge of the row covers and the type of plants you have under them. If it’s windy, the row cover can provide some protection–if they weren’t covered, they’d likely be getting whipped around a lot more. I’m curious why there’s moisture sitting on top–sure the cover would be damp with all this rain, but it should be mostly just running through.

    Best advice–pull back the cover and take a look at the plants. If they are getting really squashed or abraded, maybe take it off–or better yet support the cover with cages or hoops of wire or pvc pipe so it’s not sitting directly on top of them. Good luck!

  3. Hi Rebecca

    You very clearly have lots of experience in using FRC!

    Have you ever considered using hoops as support as part of your normal protection routine? I would be intersted to see your thoughts on them.

    Perhaps in a future post you could comment on their use.



  4. Posted by Mary on May 12, 2010 at 2:31 pm

    Thanks Rebecca. Sage advice. You rock!

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