Why Is My Cannabis Turning White?

Cannabis comes in many colors, but white is not usually one of them. If your leaves or buds are going pale, something is wrong. Kind Seed Co explains how to work out why your cannabis is turning white and what to do about it.

What turns cannabis white

Most cases come down to two things. The first is the environment. Too much light or the wrong temperature or humidity can bleach plants and strip their color. The second is pests and disease. Spider mites and aphids leave white patches on leaves and buds, and powdery mildew shows up as white, powdery spots.

True white genetics are rare. If you are curious, our article on albino weed and whether it exists explains more.

How to pin down the cause

Light, heat and humidity

Strong grow lights can cause light bleaching, which turns the tops of buds white. Temperature swings and humidity that runs too high or too low can also cause discoloration.

Keep lights at a sensible distance and set the intensity to suit the stage of growth. Our guides to the best PAR for cannabis and when to increase light intensity in flowering help you find the right level. Aim for daytime temperatures between 70 and 85°F (21 to 29°C) and humidity between 40 and 60 percent. Make changes gradually and watch how your plants respond.

Pests and disease

Spider mites and aphids feed on sap and leave pale patches or dots behind. Powdery mildew coats leaves and buds in a white, dusty fungus.

Inspect your plants regularly so you catch problems early, when they are easier to stop. Look for fine webbing from spider mites, clusters of tiny aphids or the white dusting of mildew. Left alone, any of these can spread through your whole crop.

How to fix it

Adjust your growing conditions

Check light, temperature and humidity throughout the grow and adjust as needed. A light meter helps you set intensity, and a thermometer and hygrometer give you accurate readings. Steady monitoring keeps plants comfortable and lowers the risk of whitening.

Deal with pests and disease

For bugs, bring in beneficial insects such as ladybugs or predatory mites, or use an organic insecticidal soap or neem oil.

For mildew, good airflow is key because it keeps humidity down. Sometimes simply spacing plants further apart is enough. If powdery mildew appears, remove the affected areas and apply a cannabis safe fungicide. Keep a close eye on plants for several weeks afterward, since spores can linger even when plants look clear. Our guide on how to prevent, detect and fight mildew on your weed plants covers it in depth.

When to ask for help

If whitening keeps getting worse despite your efforts, talk to an experienced grower or a horticulture expert. Their know how can save plants that look lost and help you avoid the same problem next time.

White cannabis is alarming, but it is usually fixable. Find the cause, make a few simple changes and keep watching your plants to protect your harvest.