Row cover hoops for frost and pest protection

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In my award-winning book, The Year-Round Vegetable Gardener I write extensively about the row cover hoops I use to stretch the harvest season in my vegetable garden. I use them to get a head start on spring planting, but also in autumn to protect from frost and cold weather. Simple row cover hoops can also be used during the growing season to shelter vegetable plants from pests like flea beetles, potatoes beetles, and squash bugs, or even larger pests like rabbits, deer, and birds.

Row cover hoops are one of my secrets of a healthy, long-producing vegetable garden. Plus, they’re quick and easy to set up which is very handy if an unexpected frost is in the forecast. Read on to learn more about the various ways you can use hoop tunnels in your garden, as well as the various materials I use to make my structures.

This super quick-to-build tunnel is made with wire hoops covered in a lightweight row cover. It’s protecting my collard green seedlings from cabbage moths and deer.

Two ways to use row cover hoops:

Traditionally, vegetable gardeners wait for the last spring frost to pass before planting most of their crops. By using protective covers, however, I plant weeks – sometimes months! – earlier. I’ve been using these handy covers for many years to grow more food in my garden and harvest year-round.

In spring, I’m sowing seed for cool season greens like arugula, leaf lettuce, spinach, tatsoi, scallions, and Asian greens beneath my tunnels. I’m also transplanting seedlings of crops like broccoli, cabbage, and artichokes. But, these simple covers are also a convenient way to keep frost-sensitive tomato and pepper seedlings insulated from the up-and-down weather of spring. The tunnels capture heat and create a microclimate around these tender plants which reduces the risk of cold damage.

My end-of-season basil is protected with a row cover tunnel to shelter it from cool evening temperatures and frost.

Pest protection

When using row cover hoops to prevent pests, remember that you also need to practice smart crop rotation. If you’re growing the same crop in the same bed year after year and having problems with the same pest, covering that bed with a row cover isn’t going to solve your problem. In fact, you’ll likely just trap that pest beneath the cover, giving them free rein to munch your crops. Instead, be sure to rotate crop families each year by planting them in a different bed or different section of your garden.

It’s also important to consider timing – when do you put the protective tunnel over your vegetables and how long do you have to leave them on? To be most effective, I place tunnels over my garden beds immediately after seeding or transplanting the pest-susceptible crop. Why? Because I’ve been in the garden transplanting broccoli seedlings into my garden with cabbage moths flying about my head trying to land on the broccoli plants. If you wait to cover them, you may be too late.

The length of time the crop needs to covered depends on several factors: 1) the type of pest, 2) when it’s most damaging, and 3) the type of crop. For example, flea beetles are most damaging to cabbage family crops like arugula in spring when the pests emerge from the soil. A lightweight row cover prevents them from accessing the arugula and can be left in place until you’ve harvested all of your crop. It’s a different matter for vegetables like cucumbers, squash, or melons which need to be pollinated to produce their crop. In this case, you can use row cover hoops to prevent squash bug or cucumber beetle damage to the young plants but then remove the covers when the plants begin to flower so pollination can occur.

These metal hoops will be covered with a row cover to protect the young seedlings from cold temperatures and frost.

The best materials for row cover hoops:

The materials I use for my row cover hoops are easy to source, inexpensive, and durable. To prolong their life, I store them in my garden shed or garage when they’re not in use. When making a mini tunnel, I space hoops three to four feet apart.

PVC hoops

For well over a decade I’ve been using half-inch diameter PVC conduit to make hoops for my garden beds. It’s an inexpensive product that’s easy to source at your local home improvement centre and comes in ten-foot lengths. PVC bends easily over a bed to make a quick hoop. You can insert the end of the PVC directly into the soil, but I find these hoops are more stable when a one-foot long rebar stake is inserted into the soil first and the end of the hoop is then slipped over the stake.

Wire hoops

Wire hoops are perfect for spring, summer, or autumn row cover hoops, but they’re not strong enough to stand up to any snow load so I don’t use them in the winter garden. I use nine gauge wire, which comes in a coil. I cut them into five to six-foot lengths to top three to four-foot wide beds. Once inserted into the soil, they’re about 18-inches tall. They’re fine for light frost protection, preventing fleas beetles from damaging compact crops like arugula, or for covering young squash plants to prevent squash bugs from accessing the crop.

It only takes me about one minute to bend a half-inch, ten foot length of metal conduit into a sturdy hoop for my garden beds.

Metal hoops

About five years ago I got a Quick Hoops Low Tunnel Hoop Bender from Johnny’s Selected Seeds and it transformed my winter low tunnels. I had been using PVC for these structures but I always had to add a center support down the middle to prevent them from collapsing under heavy snow. The metal hoops are much stronger and I can now build a quick mini hoop tunnel without needing to reinforce the hoops. Plus, bending a half-inch diameter length of metal conduit into a hoop takes less than one minute with the bender so it’s fast and easy to make super strong hoops. To read about my metal hoop upgrade, check out this article.

Kits for row cover hoops

Of course you can also buy pre-made mini hoop tunnels. I have several of these structures in my garden, some covered with row cover fabric and others with polyethylene. Last year, I got a Bio Green Superdome Growtunnel which has a polyethylene cover and appreciate its quick set up, height, and convenient venting sides. A row cover tunnel like a Tierra Garden Easy Fleece Tunnel is another instant structure that’s perfect for salad greens, squash or cucumber seedlings, or kale plants. If it’s insects you wish to omit, use a kit with a lightweight insect barrier cover like the Gardman Insect Mesh Grow Tunnel.

I use my Bio Green Superdome Growtunnel to shelter seedlings in the spring and fall from frost, as well as from pests like insects, slugs, and deer.

Types of covers for row cover hoops

Depending on the type of row cover, it can offer several degrees of frost protection, but remember that the thicker the cover, the less light will pass through. That’s not a big deal if you’re using it for winter protection when plants are mostly dormant. But, if you wish to encourage quick, healthy growth in spring, you’ll want a fabric that allows plenty of light transmission.

Row covers also come in a wide range of widths and lengths – read the package description carefully to make sure you’re buying the right size. Early on, I bought a seven-foot wide fabric thinking that it would be enough to cover my PVC hoop tunnels, but I was wrong! I was about six inches short on fabric and had to work hard to push the PVC hoops super far down in the soil so that I could completely cover the tunnel.

Insect barrier screening

More mesh than fabric, these durable mesh cloths prevent bugs, moths, slugs, birds, deer, rabbits, and other creatures from accessing your vegetables, herbs, or flowers, but still allow plenty of light and water to pass through.

Lightweight row covers

Lightweight row covers are the most widely used fabrics and are ideal for light frost protection, general bad weather protection (hail, downpours, etc.), and to omit insects and other garden pests. They allow about 90% of light to pass through to your vegetables and offer a few degrees of frost protection.

Row cover is one of the best ways to enjoy pest-free salad greens in spring, fall, and winter.

Medium-weight row covers

Slightly heavier than lightweight covers, these materials allow around 70% of light to pass through and provide up to a 6 degrees F (3 to 4 degrees C) of frost protection. I use these in spring or fall as a temporary cover if there is a hard frost in the forecast.

Heavy-weight row covers

Heavy-weight covers are used mainly as winter covers because they block 30 to 50% of the light. You can use them as temporary covers in the case of frost, but don’t leave them on for more than a day or two during the growing season as they block too much light.

I like to use snap clamps to hold row covers and polyethylene covers to my half-inch diameter PVC and metal hoops.

How to attach the covers on row cover hoops:

To be effective against pests, you’ll need to securely attach the covers to their hoops and weigh them down at the bottom. It’s amazing how easy it is for insects to sneak under an unsecured cover or for the cover to blow off in a storm.

There are a variety of ways to attach a row cover to a hoop. Here are the three materials I use to secure my row covers:

  1. Clips – There are many types of clips and clamps available at garden supply and hardware stores, and I’ve found snap clamps to be the most convenient. They pop on or off easily but hold the cover tight against the strongest wind gusts. Do be careful when you remove them from the hoops as if you’re not careful, you can easily tear lightweight fabrics. For insect prevention, I still secure the bottom of the row cover with weights or staples.
  2. Weights – If I’m using a cover for temporary frost protection I often just weigh down the fabric at the bottom with something heavy like rocks, logs, lumber, or small sandbags. Just be sure that whatever you use doesn’t have sharp edges which could tear the fabric.
  3. Garden staples – Garden staples or pegs do tear a hole in the fabric to hold them tightly to the soil. They work great and I don’t mind using these if I’ve got old covers, but if my covers are in good shape, I don’t like to put holes in them as it shortens their lifespan. Instead, I’ll weigh them down and use snap clamps.

For more information on protecting your crops from pests or extending the harvest, check out these posts:

  • Niki’s metal hoop tunnels
  • How to mulch root vegetables for a winter harvest
  • 8 vegetables to harvest in winter
  • Cabbage worm ID and control
  • Preventing pests in your garden: 5 strategies

Do you use row cover hoops in your garden to protect from frost or pests?

Horticultural Fleece Uses – Learn How To Use Garden Fleece

Fleece in the garden is similar to the fleece we use for blankets and jackets: it keeps plants warm. Called both garden fleece and horticultural fleece, this plant blanket is lightweight and easy to use and can provide protection against cold and frost as well as other harmful weather conditions and pests.

What is Garden Fleece?

Horticultural or garden fleece is a sheet of material that can be used to cover plants. It is similar to plastic sheeting that is often used for similar purposes, but there are some significant differences. Limitations of plastic sheets include that they are heavy and difficult to manipulate and that they tend to overheat during the day and fail to insulate enough at night.

Using horticultural fleece as an alternative to plastic has become more popular with gardeners. It is a synthetic material, made from polyester or polypropylene, and is more like a fabric than plastic. It is similar to fleece clothing, but is thinner and lighter. Garden fleece is lightweight, soft, and warm.

How to Use Garden Fleece

Potential horticultural fleece uses include protecting plants from a frost, insulating plants against cold temperatures through winter, protecting plants from wind and hail, protecting soil, and keeping pests away from plants. Fleece can be used outdoors, with containers on patios and balconies, or even in greenhouses.

Using horticultural fleece is easy because it is very lightweight and you can cut it into any shape or size you need. Protecting plants from frost is one of the most common uses. For instance, you can use the fleece to cover plants in the early spring if you are expecting a late frost. You can also cover and protect your autumn crops, like tomatoes, when early frosts are possible.

In some climates, fleece can be used to cover sensitive plants for the entire winter, allowing them to survive until spring. If you live in a windy climate, harsh winds can hinder the growth of some plants. Cover them with fleece on the windiest days. You can also cover plants during harsh weather that could damage them, like hail.

When using horticultural fleece, just remember that it is extremely lightweight. This makes it easy to use, but it also means that you need to anchor it well. Use stakes or rocks to hold it down so your plants get adequate protection.

Using Horticultural Fleece All-Year-Round

I always associate horticultural fleece with autumn. It’s one of those things that appears in garden centres in that “prepare for winter range”, along with all the stuff you buy every year but never use, like pop up bags and lawn aerator shoes.

You see magazine articles on trussing up your cordyline with fleece, and see unlikely pictures of shrubs with fleece pegged over them. I’ve tried doing that.

Usually I cause more damage than the frost would ever have done. However I know horticultural fleece has its real uses and its devotees, but I’ve never really thought about using it at different times of the year until now.

On a recent visit to Raymond Blanc’s wonderful hotel Le Manoir aux Quatre Saisons, famous not only for his food but also for the amazing vegetable gardens, I was really taken by the extensive use of fleece in summer.

This is on a rather larger scale than the average vegetable garden admittedly; the crops are precious but, I was really impressed by the results. I asked one young gardener how often they use fleece after sowing. She told me “nearly always, mainly for protection against birds, especially pigeons”, but the benefits go further than that.

I should say first of all that horticultural fleece is a light unwoven polypropylene fabric that allows filtered light and rainfall to pass through. It also filters air movement so reduces wind chill, provides some shade and holds warm air beneath it when laid across the ground.

It is available in two different weights or thicknesses qualities and different widths. The cheaper lightweight fleece usually comes in 1.2metre (4ft) width; personally I think the wider 1.5m (5ft) + is better.

The lightweight fleece is the one to use through late spring, summer and early fall. The heavier weight is the one to use for frost protection.

Uses

Basically laid across the ground, over emerging and growing shorter crops, the fleece acts as a floating mulch. It provides light shade, protection from wind which avoids drying out, protects from insect pests and bird damage.

It also helps to keep temperatures a little more constant: gentle warmth if late summer nights are cold. It does need anchoring with stones or pegs and can be trickier on exposed, windy sites.

How to use it

Inspired my visit to Le Manoir I decided to give it a go. I am also frustrated by the vegetable plot as summer progresses. As potatoes are lifted there is always bare ground and a diet of zucchini and beans to look forward to, followed by shop-bought veg.

I dug over a piece of ground and prepared the ground for sowing; I added a scattering of chicken manure pellets, watered it thoroughly and left it overnight. I should say my soil is light and sandy and prone to drying out on the surface which can be a real barrier to germination.

The following day I sowed rows of beetroot (golden), perpetual spinach, mixed mustards (for leaves) and rocket. I watered the plot thoroughly and sprinkled a few nature friendly slug pellets, especially near the edges.

I covered with the ground with fleece and anchored the edges with stones. I tried using some old fleece from the garage: waste of time. It was crumpled, difficult to sort and dirty; instead I used new from the roll. Horti fleece costs pence; in my opinion it is never worth re-using.

Of course using your nature friendly slug pellets under the fleece is an added precaution. So even reluctant users can be more confident they won’t cause harm.

Germination was quick and the seedlings seemed to be making good progress under the blanket. I watered through the fleece with a hose-end sprayer without any problems. As the crops grow you may need to adjust the fleece to give them room to grow.

Cabbage white butterflies have been fluttering around frustrated and I imagine my rocket will be free of those horrid little holes caused by flea beetles. The big advantage on my soil is that it seems to help prevent the soil surface from drying out and germination is much better.

I’m hooked. I might even go as far as to using the heavier weight fleece on a tunnel to protect some leaf crops through winter. I imagine this would make a big difference to perpetual spinach and oriental mustards which I would like to overwinter. Fleece could make me a vegetable gardener yet!

Warmacrop 30g Garden Fleece, Plant Protection

Individual Shrub Protection

Wrap around the shrub and secure with string at the base of the plant.

Greenhouse Insulation

In winter, 30g fleece may be fixed inside the glass to give a ‘double glazing’ effect. It is easy to secure, simple to remove and is re-usable. In aluminium greenhouses it may be fixed to glazing bars using clips or double-sided sticky pads. In wooden greenhouses it may be fixed to the glazing bars using drawing pins or double-sided sticky pads.

Bedding Plants

30g fleece may be used for overnight protection of bedding and other plants which are being ‘hardened off’.

Crop Protection

Certain vegetable crops may be damaged by winter frosts, in particular cauliflower. Cover crops with 30g fleece during periods of cold weather. It should, however be removed during spells of mild wet weather.

Early Potatoes

Early potatoes should be covered from planting, and the cover kept in place until there is no longer any risk of frost.

Re-use of 30g fleece

If used with care, the material may be re-used several times. It is machine washable at a temperature not exceeding 40°C. It may be easily cut with sharp scissors. When not in use, store out of direct sunlight and in a vermin proof environment.

There’s a sinking feeling that comes when you spot the first cabbage moth hovering over your garden crop. Traditional vegetable gardeners use some of the worst chemical sprays to control them. And that doesn’t always work, especially as the larvae eating your plants mature. (Personally, I’d rather eat a few worms than pesticides.) Organic gardeners hunt for egg clusters on the underside of leaves and smash them, pluck the worms that they find and even snatch the egg-laying moths right out of the air (okay, I was successful doing that once). Other natural solutions include using Bacillus thuringiensis (Bt) a least-toxic bacteria that attacks certain larvae. Or you can try Neem oil, which works on a variety of pest insects and fungal problems.

Protects against frost, insects and birds! Harvest-Guard® Floating Row Cover has “pores” large enough to let in sunlight, water and air, but small enough to keep out insect pests. A single layer protects as low as 29°F; double layer protects as low as 26°F. Available in multiple sizes.

One of the easiest methods to protect row crops from invading moths, other flying insects and larger, four-legged pests is the floating cover. Row covers are made of different materials and come in different weights but the idea is simple: they shelter tender row crops from garden pests. They are laid over plants without further support — thus the “floating” — but allow sunlight — as high as 85% or more — and moisture to penetrate. They also help to retain heat, a plus in cooler climates, and protect against wind damage. Best is the fact that they shield your plants from egg-laying moths and other flying insects, including those that spread disease. They’re good protection from cabbage moths, looper caterpillars, flea beetles (that like radishes and eggplant, among others), cucumber beetles, Armyworms, grasshoppers and even rabbits and birds (think strawberries). For a full list of pests that floating covers discourage and suggestions for both home and small commercial use, see this article from the University of Kentucky Extension Service. Here’s a video about using row covers from Michigan State University which includes an interesting tip about controlling slugs under row covers (caffeinate them).

Floating covers should be installed as soon as plants are able to support them. They can be anchored with dirt, stones or lengths of rebar. Remember to provide plenty of room for the plant to grow. Don’t think for a moment you can cover your plants and forget them. You’ll need to lift your covers occasionally to check for weeds (hint: mulching around your plants will help keep weeds down). Remember that insect or eggs that over overwintered in the soil from previous infestation might be released UNDER your cover. If you’ve had trouble in the past, you’ll want to be even more diligent about checking beneath your cover for problems. And if you’re covering plants that need pollination — tomatoes, cucumbers, squash, eggplant and the like — you’ll need to make sure that you make time for this to happen (or pollinate by hand). But mostly floating covers will do a lot of the plant care for you. For more discussion of covers go here.

Plant Covers & Protection

If you have a larger garden, you may be looking for plant netting, row covers or tunnels, as well as materials such as burlap or anchor pins. Our selection includes poly, micromesh, and fleece tunnels that will not only keep your plants protected, but also maintain your garden’s aesthetics. If you’re simply looking for a cold frame or small greenhouse to protect your plants, we carry many styles to choose from. Quality materials and easy setup ensure you can protect your plants without being in the garden all day.

Row covers and plant netting have a range of uses throughout the year. If you’re heading into spring, you can use them to keep bugs off your plants or shield young plants from harsh winds. When fall arrives, there’s a chill in the air, and like you, your plants may need another layer. Garden covers can help keep your plants warm, while still allowing rain and sun to reach them. We carry many different types of covers and materials from trusted brands such as DeWitt, Winter Wrapz, and Juwel. Shop our assortment of plant covers, garden netting and other seed starting supplies today and make sure your plants are as healthy as can be!

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