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Key takeaways
- Exclusion works best as prevention. Fit netting over vents and doors before spring pest pressure builds, and pair it with inspection of every plant you bring in.
- Finer mesh stops smaller insects but restricts airflow more. Match mesh to the pests you actually have, and add vent area or fan capacity if needed.
- Doors are the weakest point. A magnetic or zippered screen door makes it practical to keep netting closed.
- Netting also keeps pollinators out. Plan for hand pollination or bumblebees in crops that need them.
- Fasten netting firmly with lock channel and wiggle wire, battens or hook-and-loop tape. Gaps defeat the whole point.
Quick picks
- Best all-round exclusion netting: ProtekNet in the lighter weight, widely sold by US seed and farm suppliers.
- Best heavier-duty netting: ProtekNet in a heavier weight for long-term vent screens.
- Best budget netting: Agfabric insect netting.
- Best for thrips-prone houses: a fine anti-insect screen sold by mesh count.
- Best for doors: a magnetic screen door curtain or zippered screen door.
- Best way to fasten it: aluminum lock channel with wiggle wire.
How exclusion netting works
Insect netting is a fine woven or knitted mesh that lets air, light and water through but stops insects above a certain size. On a greenhouse, you fit it over the openings pests use most: roof vents, side vents, louvers, doorways and the intake side of any exhaust fan.
It won't make a greenhouse pest-free. Pests also arrive on new plants, on your clothes, and through gaps you didn't know you had. But it cuts the number of flying pests that drift in from outside, which is the steady source of reinfestation for many growers. It's also a strong partner to biological pest control: netting keeps your purchased beneficials from flying out the vents.
Mesh size: what stops what
Insect screens are sold by mesh count (threads per inch), by opening size, or by fabric weight in grams per square meter. Those systems don't convert neatly, so compare products within one system and read what pests the maker says the mesh excludes.
As a general rule, larger pests like moths, cabbage butterflies and beetles are stopped by relatively coarse mesh. Aphids, whiteflies and leafminers need finer mesh. Thrips, which are tiny, need the finest screens. Suppliers publish exclusion charts for their products, so use the maker's own pest list rather than a generic chart.
| Mesh type | Stops (per typical maker claims) | Airflow | Best use |
|---|---|---|---|
| Coarse (butterfly or moth netting) | Moths, butterflies, larger beetles | Least restricted | Summer vents in low-pest areas |
| Medium (standard anti-insect) | Many aphids, whiteflies, leafminers | Moderately restricted | Most hobby greenhouse vents |
| Fine (anti-thrips) | Thrips and smaller pests | Most restricted | Houses with recurring thrips problems |
The picks
ProtekNet insect netting (lighter weight)
$$ProtekNet, made by Dubois Agrinovation, is one of the best-known exclusion nettings in North America and is sold by suppliers like Johnny's Selected Seeds and Fedco. The lighter weight is fine enough for many small pests while staying relatively breathable. It's also used as row cover, so offcuts have a second use.
Why we like it
- Widely available from seed suppliers
- Good balance of mesh and airflow
- UV-stabilized per supplier listings
Keep in mind
- Sold in long rolls, which is a lot for one greenhouse
- Cutting and hemming needed
ProtekNet insect netting (heavier weight)
$$–$$$The heavier ProtekNet weights are sturdier and handle being fastened, stretched and brushed against for years. That makes them a better fit for permanent vent and doorway screens than for row cover. Check the listing for which pests each weight is rated to exclude.
Why we like it
- Tougher fabric
- Long service life
- Good for fixed screens
Keep in mind
- Heavier weights cost more
- Check exclusion rating per weight
Agfabric insect netting
$Agfabric sells insect netting in a range of cut sizes, which is handy if you only need to cover a few vents. It's a good way to try exclusion before investing in premium rolls. Check the listed mesh and pest rating, and expect a shorter life in strong sun than premium options.
Why we like it
- Small cut sizes available
- Low cost
- Easy to find
Keep in mind
- Shorter UV life in many cases
- Mesh ratings vary by product
Fine anti-insect screen (sold by mesh count)
$$Shade cloth and greenhouse suppliers sell anti-insect screens by mesh count, including finer anti-thrips grades. If thrips are your recurring problem, the finer grade is worth the airflow trade-off on at least some vents. Pair it with an exhaust fan sized for the extra resistance.
Why we like it
- Clear mesh ratings
- Finer grades for thrips
- Sold in custom widths
Keep in mind
- Restricts airflow most
- Needs good fastening
Magnetic screen door curtain
$A magnetic mesh curtain hangs inside the door frame and closes behind you, so the doorway stays screened while the door is open for airflow. It's the cheapest way to screen a hinged door. Choose a size that overlaps your frame and a finer mesh if the listing offers options.
Why we like it
- Closes itself behind you
- Cheap and easy to fit
- Lets you prop the door open
Keep in mind
- Mesh is often coarser than vent netting
- Magnets weaken with wear
Zippered screen door for greenhouse
$–$$Zippered mesh doors fasten over a doorway on hoop houses and film greenhouses, where a hinged door isn't practical. Look for heavy-duty zippers and a design that seals at the floor. See our hoop house guide for door framing.
Why we like it
- Fits odd doorways
- Seals well when zipped
- Easy to retrofit
Keep in mind
- Zippers wear out
- Takes two hands to open
Aluminum lock channel and wiggle wire
$–$$Lock channel is the aluminum track greenhouse builders use to attach film, and it works just as well for netting. Screw the channel around the opening, then press the zigzag wiggle wire in to lock the netting tight. It's much more secure than staples or tape.
Why we like it
- Tight, even hold
- Easy to remove and refit
- Standard greenhouse hardware
Keep in mind
- Needs a solid frame to screw into
- Cutting channel to length
Where to fit netting first
You don't have to screen everything at once. Start where pests enter most often:
- Roof vents and automatic vent openers. These are open most of the day in warm weather. Fit netting to a frame on the inside or outside of the vent, and make sure it doesn't stop the opener. See best automatic vent openers.
- Doors. Add a magnetic or zippered screen so you can leave the door open for airflow without leaving it open to pests.
- Side vents and louvers. Screen these next, especially on the upwind side.
- Fan intakes. On a fan-ventilated house, screen the intake openings. The fan pulls air through them hard.
- Gaps and seams. Seal gaps around the base and where panels meet. Draft-proofing seals help here too.
How to choose
- Know your pests. Use sticky cards to see what's actually coming in. Our sticky traps and monitoring guide explains how. Don't pay the airflow cost of anti-thrips mesh if you don't have thrips.
- Check UV stabilization. Netting in full sun degrades. Look for UV-stabilized material.
- Measure with overlap. Add enough extra on every side to fasten securely.
- Plan the fastening. Lock channel, battens, or hook-and-loop tape are all better than staples.
- Think about pollination. Netting keeps bees out. Tomatoes, peppers, cucumbers (non-parthenocarpic types) and strawberries may need help. See hand pollination and bumblebee pollination.
Installing netting on vents and doors
- Clean and dry the frame around the opening.
- Fit lock channel or battens around the outside of the opening.
- Cut netting with overlap on all sides.
- Start at the top, fasten, then work down each side, keeping the netting taut.
- Fasten the bottom last and check for gaps at corners.
- Test the vent or door through its full range of motion.
- Inspect monthly for tears, sagging and dust buildup, which cuts airflow further.
Mistakes to avoid
- Screening vents without adding airflow. Fine mesh can push summer temperatures up. Plan ventilation too.
- Leaving gaps at corners and seams. Small pests find them.
- Screening, then bringing in infested plants. Quarantine new plants first. See bringing container plants under glass without importing pests.
- Forgetting pollination. Fruit set can drop if bees can't get in.
- Letting dust build up. Dirty netting restricts airflow even more. Brush or rinse it periodically.
Frequently asked questions
Does insect netting work in a greenhouse?
Yes, as part of a wider plan. Netting over vents and doors cuts the number of flying pests drifting in from outside. It won't stop pests carried in on plants or clothing, so combine it with inspection, quarantine and monitoring.
What mesh size stops thrips?
Thrips need the finest anti-insect screens. Mesh ratings differ between manufacturers, so check the maker's own exclusion chart and pick a product rated for thrips.
Does insect netting reduce airflow?
Yes. Every screen slows air, and finer mesh slows it more. Many suppliers recommend adding vent area or fan capacity to compensate, especially in summer.
Will insect netting keep bees out of my greenhouse?
Yes, netting that stops small pests also stops bees. Crops that need pollination may need hand pollination or a bumblebee hive inside the greenhouse.
How do I attach insect netting to a greenhouse vent?
Lock channel and wiggle wire give the most secure hold. Battens screwed over the netting or hook-and-loop tape also work. Avoid staples alone, which tear out.
When should I install greenhouse insect netting?
Late fall or winter is ideal. Pest pressure is low, vents are mostly closed, and the screens are in place before spring pest populations build.