North Shore Gardening Life

Days Until First Frost

The Many Uses Of Row Cover In The Garden

By Magi Nams

What is row cover?

Row cover is the name given to a material designed to cover garden plants and create a cozy microclimate for them. It allows light, air and rain to pass through and can easily be cut with scissors to the length you need.

Also known as agricultural fabric or horticultural fleece, row cover is a white, lightweight, semi-transparent synthetic material made of spun-bonded polyester.  It looks gauzy, rather like flattened cotton candy or the interfacing used in sewing.

It comes in different sizes and weights or thicknesses, and is available from many garden centres and seed supply companies.

It has been in use in commercial horticulture since the 1950s, and home gardeners have been using it for decades.

This is the fabric row cover in my garden in 2022

Why use row cover?

Row cover serves three main functions for home and commercial gardeners:

  1. It creates a favourable microclimate for seed germination and plant growth – particularly for tender plants;
  2. It provides frost protection which allows the growing season to be extended into spring and fall;
  3. It guards against pests.

Which weight do you need?

There are three types of row cover.  

  1. Lightweight allows 90-95% of natural light to pass through and works great as an insect barrier.  It offers the least amount of frost protection.
  2. Medium-weight allows 70-85% of light to pass through, and it offers good frost protection for spring and fall crops.
  3. Heavyweight allows only 30-50% of light to pass  through, and is best used for overwintering crops.

How to install row cover

Row cover is often installed over hoops to create a tunnel shelter for plants.  Inexpensive hoops can be made from cheap hula-hoops, metal cable or polypropylene tubing.  The hula-hoops do degrade and become brittle over the years.

The fabric can also be laid directly on plants in which case it’s known as “floating row cover.” It is pushed up by the plants as they grow.  Because it’s very light, row cover is easy to spread over plants and doesn’t weight them down.

Whichever method you use, you must secure the fabric to the ground by piling soil, placing bricks or using some kind of fastener along the edges.  This will prevent the wind from blowing the cover off and stop pests from getting in.

After installing a row cover, I inspect it for tears or holes.  If I find one, I mend it by folding one raw edge of the fabric over another and stapling them together.

When I remove the cover from my garden at the end of the season, I hang it on the clothesline to dry and let the soil particles blow away.  Then I wash it and hang it out to dry, after which I store it in metal garbage cans in my garden workshop to protect it from insect and rodent damage.

How I use row cover in my garden

In my garden, I use row cover for all three of its functions: creation of a favourable microclimate, frost protection, and pest protection. 

Favourable microclimate

 I plant squash, cucumber, zucchini, melon, and basil seeds directly in the soil in late spring and cover the rows or hills with medium-weight row cover.

The floating row cover helps to warm the air and soil, creating a very advantageous microclimate for sprouting and growth 

When the cucurbit plants are large and blooming, I remove the cover so they can be pollinated.

Depending on the kind of spring we’re having here in northern Nova Scotia, I’ve also at times used row cover over hoops to create a warm tunnel microclimate for young tomatoes, eggplants and peppers until they’re well-established.

Frost protection

In shoulder seasons, if the forecast low temperature is near, at, or just below freezing, I cover frost-tender plants with medium-weight row cover, or, in a pinch, light-weight row cover doubled. (I don’t have heavy-weight row cover.) 

Pest Protection

This is a biggie!!!

1. Striped cucumber beetles and squash bugs.

The row cover protects squash-family plants from striped cucumber beetles and squash bugs.  By the time I uncover my plants at the flowering stage, they’re usually (not always) strong enough to withstand any of these insect pests that are still around.

2. Colorado potato beetles

Two years ago in mid-May, my husband visited a market gardener and told me that the gardener’s early potato plants were nothing but bare stems due to a heavy potato beetle infestation.

My own plants were barely sprouting, but I decided that if it was going to be a bad potato beetle year, I had to do something.  After a little online research, I checked my plants for egg masses (none) and then installed light-weight floating row cover over my potato row. 

As the potatoes grew, they pushed up the fabric until they outgrew it, but by then they were strong and lush. I still patrolled for beetles and found a few. 

Last summer, I covered my long potato row with light-weight floating row cover right after planting and had zero potato beetle damage to my spuds. (Hooray!) 

An added benefit was only minor flea beetle damage to potato leaves.

3. Slugs

Because I have a no-till garden mulched with straw, I have problems with slugs eating newly sprouted veggies, particularly carrots. 

During the last two growing seasons, I installed lightweight floating row cover over my carrots (with radishes mixed in). I had excellent germination and growth, and last year grew the lushest radishes and carrots I’ve ever grown.

This strategy works for beets as well.

4.  Cabbage butterfly caterpillars and flea beetles

We all know how flea beetles and cabbage butterfly caterpillars love to munch on veggies in the cabbage family.

I’ve used lightweight row cover over hoops to protect broccoli , cauliflower, cabbages, bok choy and kale, and it works fairly well.  Although some years I had issues with bolting and too much humidity under the cover, leading to mould.

Cabbage family plants are cool-season crops and don’t need microclimate amelioration, so I’ve switched to using insect netting – another kind of row cover – over hoops, and this works well for me.  Much less bolting and fewer fungal issues.

 5.  Crows

One summer, I planted my corn and went off on a vacation for two weeks. When I returned home, I had no corn sprouting. I planted again and went off on another trip. Again, no corn growing on my return.

When I mentioned this corn failure to a gardening friend, he asked, “Do you have crows around?” I told him I had a breeding pair. “Well, there’s your answer. They eat the newly sprouted kernels.” 

I planted a third crop of corn and did an experiment to test whether my friend was right. I covered most of the corn with medium-weight floating row cover to act as barrier protection but left a small area of corn uncovered.

Sure enough, the corn seeds under the row cover sprouted and grew, undisturbed, while only two or three corn plants grew in the unprotected area. 

Since then, I routinely protect my planted corn with row cover until the plants are three or four inches high, at which point I remove the cover. At that stage of growth, the corn isn’t bothered by crows.

I often joke that row cover is the answer to every gardening problem, but there is one disadvantage:  the weeds grow very quickly under it, so at least once or twice during the growing season you will have to lift the cover, weed by hand, and then put the cover back.  You can’t have everything, can you?

Here is my garden in the process of planting in June last year.  

Some insect netting and row cover already in place.

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