Symptoms:
Leaf Colour:
Edges Appear Brown or Burnt
Yellow Leaves - New Growth
Dark or Purple Leaves
Brown or Dark Spots
Leaf Symptoms:
Upper Leaves / Newer Growth Affected
Leaf Edges Appear Burnt
Spots
Twisted Growth
Abnormal Growth
Leaves Curl Under
Leaves Curl Upwards
Wilting / Drooping
Plant Symptoms:
Twisted Growth
Leaves Curl Under
Plant Wilting / Drooping
Are tips/edges of leaves brown or burnt?: Yes
Spots on Leaves?: Yes
Most indoor cannabis growers use fans to blow air around within the grow area. This creates a nice breezy environment that cannabis plants love. But sometimes there can be too much breeze!
Be Careful! Too Much Wind Causes Clawed Leaves and Sometimes Spots
When there’s too much breeze, the affected marijuana leaves will start getting “wind-burned.”
Another example of cannabis wind burn in the flowering stage - they plant had twisted, unhappy leaves where the fan was blowing on them. It almost looks like root problems!
Wind-burned leaves are often curved under and form “claws.” They can look like they’re droopy from overwatering, under-watering, or possible a nitrogen toxicity, but you know you’ve got wind-burn when the leaves in front of the fan are clawing, and leaves further away from the fan look fine.
Sometimes too high levels of wind can cause other unusual problems on the affected leaves, such as brown or bronze spots that almost look like burn marks. These are the result of the leaf not being able to fulfil all its normal processes.
A close-up of those wind burn leaf spots - not bugs, not a nutrient deficiency!
Placing Fans
Ideally you’d like a nice breeze surrounding the main canopy, which means you want air blowing above and under the plants.
All the leaves should be gently rustling in the best-case scenario, but should never be waving around.
Don’t point a strong fan directly at a plant, because too much wind can start to damage the leaves and stems. Sometimes if you have a small space it's better to point the fan at the wall than directly at the plants.
After placing fans, check around the grow area to make sure that all parts get a slight breeze. If you feel stagnant air or a lack or breeze, you may want to adjust your fans.
Small oscillating fans are great for the grow space since they’re cheap and can be used to provide a nice gentle breeze to a relatively wide area without blowing on any one part too long.