Insect netting is a lightweight mesh barrier that physically blocks pests from reaching your plants without any chemical sprays. It works for everything from backyard vegetable beds to commercial greenhouses, and choosing the right mesh size is the single most important decision you’ll make. Too coarse and small pests slip through; too fine and you choke off airflow and light.
Mesh Size: Matching the Net to the Pest
Mesh size is measured two ways: by the number of threads per inch (the “mesh count”) or by the actual hole opening in millimeters. Both numbers matter, because thread thickness varies between products. Here’s how the most common commercial ratings break down:
- 17 mesh (1.42 mm openings): Blocks cabbage root fly, onion fly, carrot fly, and most moths and butterflies. Allows about 75% light transmission and 16–18% shade. This is the standard weight for general garden use.
- 25 mesh (0.77 mm openings): Fine enough to stop aphids, flea beetles, allium leaf miner, and leek moth. Light transmission drops to around 60%, with 18–20% shade.
- 32 mesh (0.60 mm openings): Targets thrips and whiteflies. Shade increases to 20–22%, and light drops to roughly 45% of full sun.
- 40 mesh (0.40 mm openings): Used primarily in greenhouses where very small pests like certain mite species or tiny whitefly are a concern. Light transmission falls to about 35%.
- 50 mesh (0.27 mm openings): The finest common option. Blocks nearly everything but reduces light to only 20% of full sun and shades 25–29%. Only practical in high-light climates or for short-term use.
The standard 1.3–1.4 mm mesh that most garden centers sell is reliable against larger flies and caterpillar-laying moths but unreliable against aphids, flea beetles, and leaf miners. If those smaller pests are your main problem, you need a fine mesh of 0.8 mm or smaller, which corresponds to 25 mesh or higher.
How Mesh Size Affects Light and Airflow
Every step finer in mesh trades pest protection for growing conditions. A 17 mesh net lets three-quarters of available sunlight through, which is plenty for most vegetables. Jump to 50 mesh and you’re down to a fifth of the light, which can stunt fruiting crops like tomatoes and peppers. Airflow follows the same pattern. Finer nets trap more heat and humidity underneath, raising the risk of fungal diseases in damp climates.
For most home gardeners, 25 mesh hits the sweet spot: it stops the widest range of common pests while still letting enough light and air through for healthy growth. If your main concern is cabbage white butterflies or carrot fly, the cheaper 17 mesh net does the job fine.
Materials and Lifespan
Most insect netting is made from high-density polyethylene (HDPE), the same plastic family used in milk jugs but woven into fine threads. The critical difference between a net that lasts one season and one that lasts five is UV stabilization. Untreated polyethylene breaks down in about nine months of sun exposure. A properly UV-stabilized insect net lasts three to five years, while fine anti-aphid nets with heavier UV packages can hold up for five to seven years.
Black nets get some natural UV protection because the carbon pigment physically blocks radiation. But color alone isn’t a substitute for chemical UV stabilizers. A white or green net with proper UV treatment will outlast a cheap black one without it. When manufacturers list a lifespan, they typically mean the point where the net retains only 50% of its original strength, not the day it falls apart. You’ll usually notice fraying and small tears well before that threshold.
Store netting out of sunlight when it’s not in use. Folding it into a dark shed or garage between seasons significantly extends its working life.
Supporting the Net Off Your Plants
You can drape insect netting directly on top of low-growing crops like carrots or radishes. The mesh is light enough that it won’t crush foliage, and the plants simply push it upward as they grow. But for taller crops, or anything where the net pressing against leaves creates entry points for pests to bite through, support hoops make a real difference.
Small hoops bent from fiberglass rods or heavy-gauge wire work well for garden beds. Push the ends into the soil on either side of the row to create an arch, spacing hoops every three to four feet. This creates a buffer between the mesh and the plant canopy, prevents leaf damage from wind-driven abrasion, and gives crops room to grow upward. For larger-scale plantings, half-inch or three-quarter-inch electrical conduit tubing bent with a hoop bender creates sturdier, taller tunnels.
Sealing the Edges
A net with gaps at the soil line is worse than no net at all. Pests that do find their way in get trapped in a predator-free environment and multiply fast. Bring the netting all the way to the ground on every side and anchor it with sandbags, rocks, or a thick layer of mulch. Some growers bury the bottom few inches of netting in a shallow trench and backfill with soil for a complete seal.
Check edges after wind or heavy rain. Even a small lift at one corner is enough for cabbage moths or flea beetles to find their way in. If you need regular access for weeding or harvesting, anchor one long side permanently and weight the opposite side with something easy to lift and replace.
Managing Pollination Under Netting
Leafy greens, root vegetables, and brassicas don’t need insect pollination, so they can stay covered from planting through harvest. Fruiting crops are a different story. Cucumbers, squash, melons, and other cucurbits depend entirely on bees and other insects to move pollen between flowers. Without pollinators, you get flowers but no fruit.
Three strategies handle this well:
- Remove at flowering: Keep nets on during the vulnerable seedling stage, then remove them permanently once the first female flowers appear. This gives you early-season protection when pest damage is most devastating, then lets pollinators do their work. The nets don’t go back on.
- Remove and replace: Take the nets off when flowering begins, leave them off for about two weeks while pollination happens, then reinstall them for the rest of the growing season. This works best when late-season pests like squash vine borers are a concern.
- Open the ends: Instead of removing the entire net, open just the ends of your row tunnel during flowering. Research at the University of Kentucky found successful pollination along entire 120-foot tunnels using this approach. Bees enter from the open ends and work their way down the row.
Choosing the Right Net for Common Garden Crops
For brassicas (cabbage, broccoli, kale, Brussels sprouts), the standard 17 mesh handles the main threats: cabbage white butterflies and cabbage root fly. You can leave these crops covered all season since they don’t need pollination. Carrots benefit from the same 17 mesh, which blocks carrot fly effectively. Onions, leeks, and garlic need 25 mesh or finer to stop allium leaf miner and leek moth, both small enough to pass through standard netting.
For crops plagued by aphids or flea beetles, like salad greens, Asian vegetables, or young brassica transplants, step up to 25 mesh. The slight reduction in light is rarely a problem for leafy crops. For greenhouse growers dealing with whitefly or thrips, 32 mesh or finer is necessary, though you’ll want to monitor temperatures closely since the reduced airflow can push greenhouse heat to damaging levels on sunny days.
Whatever mesh you choose, install the netting before the target pest is active. Netting works as a barrier, not a treatment. If pests are already on your plants when the net goes on, you’ve locked them inside with an all-you-can-eat buffet and no natural predators to keep them in check.