Cabbage, kale, broccoli, cauliflower, and Brussels sprouts are productive garden crops. They are also common targets for cabbage worms, diamondback moths, flea beetles, aphids, and cabbage root flies.
The good news: you can protect brassicas without relying on chemical sprays. Insect netting for brassicas creates a physical barrier between your plants and many common pests. When installed early and sealed well, it helps you grow cleaner leaves and healthier heads with less daily pest control.
This guide explains how to choose between insect netting and row cover, how to install it, and how to keep your brassica bed protected through the growing season.
Why use insect netting for brassicas?
Insect netting works by stopping adult insects from reaching your plants. If moths and flea beetles cannot land on the leaves, they have fewer opportunities to feed or lay eggs.
A properly installed cover can help protect:
- Cabbage
- Kale
- Broccoli
- Cauliflower
- Brussels sprouts
- Collards
- Turnips
- Radishes
- Other leafy brassicas
The approach is simple:
- Cover plants before pests arrive
- Keep the mesh above the foliage
- Seal every edge and corner
- Check the crop regularly
- Replace the cover after watering or weeding
For additional background on physical crop protection, see our guide to large insect netting for protecting crops without chemicals.
Insect netting vs. floating row cover
The terms are sometimes used together, but insect netting and floating row cover are different materials.
Insect netting
Insect netting is a knitted or woven mesh designed to let air, light, and rain pass through while blocking pests. It is often the better option for warm-weather brassicas because it adds little insulation.
Use insect netting when your main goal is:
- Blocking cabbage moths
- Reducing flea beetle damage
- Protecting plants during warm weather
- Allowing rainfall and irrigation through
- Keeping the crop close to normal outdoor temperatures
Floating row cover
Floating row cover is a lightweight spunbonded fabric. It can exclude insects, but it may also hold in more heat than open mesh.
Row cover is useful when you need:
- Early-season frost protection
- A warmer growing environment
- Short-term protection after transplanting
- A lightweight barrier over small plants
As temperatures rise, many growers switch from fabric row cover to insect netting. The best choice depends on your climate, planting date, target pests, and the level of frost protection you need.
The University of New Hampshire Extension provides additional guidance on using row covers in the garden.
Choose the right mesh for your pest problem
Mesh size matters. A net that blocks larger moths may not stop small flea beetles or cabbage flies.
As a general starting point:
- Cabbage worms and moths: approximately 1.0–1.5 mm mesh may provide useful exclusion.
- Flea beetles: choose a finer mesh and seal the edges carefully.
- Aphids and cabbage flies: a tighter mesh may be needed where these pests are a regular problem.
- Mixed pest pressure: a fine mesh around 0.6–1.0 mm is often considered for broad protection, depending on the product and local conditions.
These ranges are guidelines, not a guarantee for every pest or growing region. Very fine mesh can reduce airflow slightly, and the material must still be large enough to fit over the crop with room for growth.
If you are unsure which mesh to select, contact American Nettings & Fabric for help matching the netting to your crop, pest pressure, and bed size.
For pest-specific information, review:
- University of Massachusetts guidance on managing brassica insect pests
- University of Massachusetts information on flea beetle biology
- Agriculture and Agri-Food Canada research on row covers for cabbage maggot management
Install the cover immediately after planting
Timing is one of the most important parts of successful insect exclusion.
Install the insect netting:
- Immediately after direct seeding
- As soon as transplants are planted
- Before flea beetles begin feeding
- Before cabbage moths can lay eggs
Do not wait until the leaves show heavy damage. A cover can stop new pests from reaching the crop, but it will not remove insects or caterpillars already under the netting.
Before covering:
- Inspect every plant.
- Remove visible caterpillars, eggs, and beetles.
- Check the undersides of leaves.
- Confirm that seedlings are healthy.
- Cover the bed the same day.
If pests are already inside, the netting may protect them along with the plants.
Build a simple low tunnel
Insect netting should be supported above the plants rather than laid directly on the leaves. Hoops create a simple low tunnel and give brassicas room to grow.
Suitable supports include:
- Fiberglass garden hoops
- Smooth wire hoops
- PVC hoops
- Lightweight metal hoops
- A simple wood or pipe frame
Place the hoops across the bed and space them closely enough to prevent the netting from sagging. Larger plants need taller supports and more slack.
The goal is to create a covered space where:
- Leaves do not press against the mesh
- Plants can continue growing
- Wind cannot pull the netting onto the crop
- Water can pass through
- You can lift one side for maintenance
Leave extra material at both sides and at the ends. A cover that is too short is difficult to seal and may leave gaps.
Seal every edge and corner
A small opening can be enough for flea beetles or moths to enter. Edge sealing is especially important when using insect netting for brassicas.
Secure the netting with:
- Soil along both sides
- Landscape staples
- Sandbags
- Smooth rocks
- Bricks
- Clips attached to the support frame
Pay close attention to the ends of the tunnel. The corners and end flaps are common entry points.
A reliable installation should have:
- No open gaps at ground level
- No loose corners
- No tears in the mesh
- Secure fasteners along the frame
- Enough slack for plant growth
Keep the mesh taut enough to prevent excessive flapping, but do not stretch it so tightly that it tears or pulls away from the soil.
Watering, weeding, and checking the crop
Most insect netting allows rain and irrigation to pass through. You can usually water the plants without removing the cover.
For larger maintenance jobs:
- Lift one side of the netting.
- Work quickly.
- Inspect the plants.
- Lower the netting again.
- Reseal the edge before leaving the bed.
Avoid leaving the bed open for long periods. One uncovered afternoon during high pest activity can undo careful preparation.
Check the cover at least once a week for:
- Holes
- Loose staples
- Lifted corners
- Plant growth pressing against the mesh
- Wind damage
- Insects trapped inside
A quick inspection also gives you a chance to check soil moisture and plant health.
How long should the netting stay on?
For cabbage, kale, broccoli, and other brassicas grown for leaves or heads, insect netting can often remain in place through much of the growing season.
Keep it on during the period when:
- Plants are young and vulnerable
- Flea beetles are active
- Cabbage moths are laying eggs
- Leaves are expanding
- Heads are forming
Brassicas grown for leaves or heads do not need insect pollination for the harvestable crop. This means they can remain covered without the pollination concerns associated with flowering fruit crops.
If you grow brassicas for seed, however, the cover will need to be managed differently. Flowering plants require access for pollination unless you are handling that process yourself.
Remove or lift the netting when:
- Plants have outgrown the tunnel
- The crop needs major work
- Temperatures and airflow become a concern
- You are preparing plants for seed production
- Harvest access requires a larger opening
Prevent heat and moisture problems
Fine insect netting usually adds less heat than fabric row cover, but every covered bed still needs monitoring.
During warm weather:
- Use netting that allows good airflow
- Avoid pressing the material against the foliage
- Check plants during hot afternoons
- Water as needed
- Open the cover briefly if conditions become excessively hot or humid
A well-supported cover helps air move around the crop. It also reduces the chance that wet leaves will remain trapped against the material.
Use the same system for home gardens and commercial beds
The basic method works for a small raised bed, a backyard row, or a larger commercial planting:
- Select the appropriate mesh
- Measure the bed and plant height
- Install a stable support system
- Cover early
- Seal the perimeter
- Inspect and maintain the barrier
For a small garden, a few hoops and landscape staples may be enough. For larger fields or repeated plantings, continuous rolls of netting can reduce seams and make installation more efficient.
American Nettings & Fabric offers practical netting solutions for home gardeners, growers, landscapers, and agricultural operations. With a broad range of sizes and long experience in specialty fabrics, the team can help you compare options for your brassica beds.
Grow cleaner brassicas with a simple barrier
Insect netting for brassicas is a practical way to reduce cabbage worm and flea beetle damage without routine spraying. The system does not need to be complicated. Start with clean plants, install the cover early, choose mesh for your most difficult pest, and seal every edge.
Protect your next cabbage, kale, and broccoli planting with a reliable physical barrier. Explore insect netting solutions or contact American Nettings & Fabric for help choosing a suitable setup.