Wind burn is a form of stress. Plants respond by curling their leaf tips under or “clawing” when ventilation is too strong. In the worst cases, leaf tips and edges can become desiccated.
Wind burn is one of those rare cannabis symptoms that is more about prevention than cure.
Once plants are wind-burnt, the damage is already done. Poorly watered plants that are drooping and already under stress can be killed by the extra stress of wind burn, but unless the plants were dehydrated before the wind burn, then the problem is really cosmetic.
Wind burn rarely occurs outside with well-watered plants. Even on the hottest, windiest days, plants will thrive outdoors. Wind burn happens more often within the indoor grow-op. When fans are awkwardly placed too close to plants or are set too strong, wind burn can happen. Your plants will start looking stressed and the growth will slow down.
Depending on the amount of harm done, long-term plant performance can be affected as there is less leaf surface area due to damage. Solving the wind problem will see plants return to good health and keep growing well.
They will just look a bit ragged where leaves or dried edges of leaves have been removed. End yields may be affected due to compromised plant performance, but cannabis is a very hardy species. It can bounce back from a number of ailments.
If you think end yields might be compromised, veg the plants for an extra week to make up for the time spent under stress. Plants are rarely burnt during flowering as the problem would have been identified and solved before bloom began.
Plan ahead when preparing an indoor cannabis grow. Jamming plants into a grow space in an effort to get more bud at harvest time usually backfires. Marijuana requires shoulder room to grow at its best.
Unless you are purposefully going for a sea of green (SOG) setup, make sure to allow each plant adequate space. A number of problems, including wind burn, can occur when there a too many plants per square meter.
Seedlings and young cuttings are better off without any direct ventilation, as they are very fragile and this might damage the plants. During the first 2 weeks of their life cycle it is better to point the ventilators towards the sides of your tent or the lights. This way the plants will receive indirect air blows, but still giving them all the aeration needed to thrive.
Always have fans set on oscillate, and be sure they have multiple speed settings. When placing your fans, make sure they are not too close to your plants. Air movement is necessary for stem strength, efficient gas exchange, and to ensure healthy transpiration, but leaves should vibrate and flutter, not be blown wildly around. When this is the case, your fans are placed either too close to the plant, or have too much power.
When placing your fans, you want them to receive a bit of breeze from each side, and placing some lower and some higher would be the ideal set up.
When ventilation is too strong in an effort to make sure the whole crop receives moving air, the plants closest to the fans can get wind burnt. Even distribution of plants, proper fan placement, and moderate speed settings will prevent wind burn in most cases.