Using Garden Covers Is a Must If You're Gardening Organically

I'm sure you've heard the expression "an ounce of prevention is worth a pound of cure." When it comes to gardening, prevention will be measured in yards instead of ounces—yards of fabric, that is.

It took me a few years of gardening (and one devastating cabbage looper infestation in my salad garden) before I realized the simple power of a couple yards of fabric. Garden covers won't just protect your leafy greens from caterpillars. Oh, no. They can do so much more.

Once I saw how effective covering my garden to prevent pests was, I branched out. I started using shade cloth to protect my tomatoes over the hot summers in Houston and frost cloth so I could plant my salad garden as early as possible after a bitter Chicago winter.

If you’ve had pest frustrations or you’re feeling limited by the extreme heat or cold in your local climate, garden covers may just be the one thing your organic garden is missing. 

So when exactly should you cover your plants with a protective layer? 

Let's look at how to use covers to ensure garden success whether you’re fighting pests, braving the cold, or surviving the heat so that your garden stays beautiful and productive throughout more of the year. 

Use Garden Covers to Guard Against Frost

When the temperatures start dipping into the 30s overnight and frost looms, it’s a great time to think about covering your vegetable garden. 

Light Frosts

Even a light frost, which occurs when temperatures drop to around 32°F, can damage tender lettuces, radishes, and any plants that aren't frost hardy. (That would include the majority of our favorite fruiting plants, like tomatoes and cucumbers.)

For a light frost, a simple floating row cover, some frost cloth, or even just some old blankets or sheets can provide enough protection to keep your plants warm. Make sure to use landscaping pins, bricks, or rocks to secure your cover in place.

I used frost cloth in my garden in Houston when the temps would drop below freezing for just a night or two. After these light freezes, the temps would often stay above freezing for many more weeks. It’s in these cases that taking a few moments to cover your garden before nightfall can really pay off. If you keep your frost-sensitive plants safe through those one or two nights of frost, you’ll get weeks more of growth from your plants. 

Moderate Frosts

A moderate frost, with temperatures ranging from about 28°F to 32°F, necessitates a bit more precaution. In addition to tucking your plants in well with some frost cloth or cover, it's also a good idea to water your plants the evening before frost is expected to hit. Wet soil releases heat more slowly than the surrounding air, so your plants should be nice and cozy under their covers. I'm not a fan of using mulch in the vegetable garden, so I recommend adding some organic compost around the base of your plants in lieu of mulch before the temperatures drop below freezing. The compost can also help trap the soil’s heat.

Severe Frosts

Severe frost happens when temperatures drop below 28°F, and this is what we call a "killing frost". When severe frost is in the forecast, you’ll want to be sure you cover all your plants in your vegetable garden, even the frost-hardy plants like kale and cabbage.

You might consider adding a plastic tarp over your old blankets or frost cloth (just make sure to use garden hoops to keep the plastic from coming into direct contact with your plants. You could also use garden cloches, cold frames, or even burlap sacks. These covers will only prove effective if you ensure that they extend down to the ground so that they can trap the soil's heat effectively. (Again, use landscaping pins or something heavy to hold the covers in place.)

Use Garden Covers to Shelter Your Plants from Heat and Intense Sunlight

Long before I lived in Chicago and experienced a climate that might as well have been the Arctic as far as I was concerned, I was gardening in pretty much the complete opposite climate down in Houston. There, it was the extreme heat and sunlight that I needed to protect my plants from over Texas's long, brutal summers.

While we all know that sunlight is critical for your garden to be productive, there is such a thing as too much heat and sunlight, especially for fruiting plants like tomatoes, peppers, and cucumbers. These plants prefer when temps range between 65 and 85 degrees. Too much sun during periods of hot weather can actually kill plants that prefer the cool and warm growing seasons. Even if your plants don't die, you'll face problems like wilting leaves, sun scald, and soil that's completely dried up.

During the sweltering days of summer when the temperatures are regularly above 90°F, you can use shade cloth to lower the temperature underneath the cover. This is really the best and only way to protect your plants during such an extreme period. (It's also a good idea to keep the roots of your plants well watered, which likely means watering every morning.)

Shade cloths work by filtering out a percentage of the sun’s rays and keeping the soil several degrees cooler. You don't want to completely block out the sunlight, just filter enough of the light to give your plants some relief. This can delay your cool and warm season plants from bolting (going to seed) by at least a few weeks.

Use Garden Covers to Defend Against Pests

I've already mentioned how the first time I ever used garden covers was in response to my salad garden being decimated by hundreds of destructive little green caterpillars.

I was hoping to avoid using chemical pesticides. That was pretty much the last thing I wanted on my homegrown lettuce leaves (the wriggling pests were a close second to last), but there were too many pests to remove by hand. I cleared the bed and started from scratch. But this time, I added a key component of organic pest control. I covered my lettuce seeds the very day I sowed them with garden mesh fabric.

This cover made all the difference. But the trick is putting a cover on the moment you plant your seeds—not weeks after when you see your first squishy little caterpillar body hanging out on the underside of a leaf!

Floating row covers, garden mesh (also called ag fabric), and even inexpensive yards of tulle from the fabric store are a perfect way to keep pests like aphids, caterpillars, and beetles off of your vegetables, without the need for chemical sprays (which I try to avoid at all costs). 

For larger pests like squirrels, birds, moles, and more, you can use fencing, covers made of thicker nets, or hardware cloth to keep them out of the garden space.

Of course, with all covers, the goal is not to harm wildlife, just to be sure you get to your harvests before they do!

Covers work best for leafy greens and veggies like broccoli and cauliflower. Using covers for fruiting plants can also be helpful, but these plants will eventually need to be pollinated by bees and butterflies. Garden covers don’t just keep the bad bugs out, of course; they bar the good ones too. You can always lift the covers during the day to give pollinators access and then pin them back down at night.

Learn more about using garden covers to protect against pests.

Timing Really Matters When Using Garden Covers

Knowing when to cover and uncover your garden takes some practice. 

For frost protection, it's best to cover your plants late in the day to trap all the heat that’s built up in the soil throughout the day. Then, be sure to remove any frost coverings when the temperature rises the next day. Otherwise, you risk overheating your plants (something that’s definitely happened to me!).

When there’s extreme heat or too much sunshine, put out garden covers by mid-morning and leave them on throughout the hottest part of the day. Either remove the shade covers in the evening when the temperatures start to drop or leave them on during the entire heat wave.

For pest prevention, the timing varies based on the pest you're trying to deter. Continual coverage might be necessary for smaller insects, while temporary barriers can work for larger pests. I’ve found, for example, that I need to protect my garden from squirrels more often during hotter or dryer parts of the season. 

Covering Your Garden Can Extend Your Growing Seasons and Protect Your Crops

Covering your vegetable garden is an incredibly effective (and simple!) organic strategy to manage the impacts of all kinds of external threats—everything from an increasingly warmer summer season to hungry, hungry cabbage loopers.

With the right cover, you can extend the total time you get to enjoy your garden by planting earlier in the spring and pushing later into the fall, and perhaps even gardening through the extreme heat of summer or the bitter cold of winter.

And of course, if you've been stressing about pests, covers can really be your savior. You'll be happier, your plants will be healthier, and you get to pick your tomatoes before the squirrels do. 

We focused here on when to use covers for best results. Check out this article to learn more about the different types of covers for each growing season and how to install them.

Here's to longer growing seasons and fewer garden pests!