The instinct is to block as much wind as possible. In practice that's usually wrong — a too-solid barrier creates turbulence and humidity that harm crops more than the wind did. Porosity is the number that gets it right.
Windbreak netting works by slowing wind gradually, not by stopping it dead. Its porosity — the percentage of open area that lets air pass through — is the single number that decides whether your barrier protects the crop or quietly damages it. Get it right and a net shelters a protected zone several times its own height; get it wrong and you build a turbulence machine. Here is how to choose.
The goal of a windbreak is not to stop wind completely. A solid wall — 0% porosity — forces wind up and over the top, where it dumps back down in a violent, turbulent eddy on the leeward side. That turbulence does more damage to the crops just behind the barrier than the open wind ever did, and the still air it traps breeds humidity and fungal problems.
A porous net instead bleeds the wind through in small streams, reducing its speed smoothly and evenly. The air stays moving, stays dry, and the crop behind gets real protection without the moisture trap.
For most farms, 50% porosity is the reference point. It breaks strong wind into smaller, gentler streams, reduces direct pressure on the crop, and creates a protected zone of roughly 6–8 times the height of the net downwind. It is the balanced default — enough protection for vegetables and orchards, enough airflow to avoid stagnation.
| Site / crop | Porosity | Why |
|---|---|---|
| Coastal / strong-wind zones | 30–40% | Denser net for constant high wind |
| Mixed farms, vegetables | 40–50% | Protection with airflow |
| Orchards & citrus | 50–55% | Placed 2–3 m from the tree line |
| Greenhouses & nurseries | 70–80% | Light protection, high light & air |
The pattern is simple: the harsher the wind, the lower the porosity; the more delicate the airflow needs, the higher. Resist the urge to “over-protect” with a tight net — a 75%-blockage net sounds stronger but creates the humid, stagnant pocket that brings on fungal disease.
Measurements tell the same story. At two barrier-heights downwind, the reduction in wind speed is surprisingly close across the useful range: a 20% porosity net cuts wind by about 62%, while a 50% porosity net still delivers around 52%. In other words, you get nearly the same protection at 50% as you do at 20% — but with far better airflow and a lower risk of the turbulence and humidity problems that come with a dense net.
A windbreak is not a wall you butt up against the crop. Give it 2–3 m of space from the tree line or row so the slowed air can settle before it reaches the plants. Placing a dense net too close concentrates the turbulence right on the crop it is meant to protect.
The protected zone extends roughly 6–8 times the net’s height downwind, so size the net’s height to how far back you need coverage, not just to the crop’s own height. String it taut on posts or a frame — a windbreak that flaps is fighting the wind instead of managing it, and it wears out its fixings fast. Our knitted HDPE windbreak net is built for exactly this: strong, UV-stabilised, and made to the porosity your site actually needs.
Not sure whether you need 40% or 60%? Tell us your site, prevailing wind and crop and we’ll recommend the right porosity and height.
See also our windbreak netting installation and the livestock shade netting.
50% is the balanced default for most farms. Drop to 30–40% for coastal or strong-wind zones, and rise to 70–80% for greenhouses and nurseries that need light and airflow.
No. A solid barrier forces wind up and over, creating turbulence and trapped humidity that harm crops. A porous net slows the wind smoothly and keeps the air moving.
Roughly 6–8 times the height of the net downwind. Keep the net 2–3 m from the crop so the slowed air settles before it reaches the plants.
No. A 50% net delivers nearly the same wind reduction as a 20% net, with far better airflow and none of the humidity problems that come with a too-tight barrier.
Start at 50% porosity, go denser only in truly harsh wind, and keep the net 2–3 m from the crop. Tell us your site and we’ll spec the right windbreak net.
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