I just noticed some spotting on some of my fan leaves. They are brown and orange and only on a couple of fan leaves. What does this mean and should I be concerned?

Hugo, Madrid

Grow guide for marijuana beginners.


Your plants are showing the first signs of a nutrient buildup in the soil, probably potassium. Nutrients are classified as mobile or immobile within the plant. Mobile nutrients-nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and zinc (Zn)-are able to translocate, move from one portion of the plant to another as needed. For example, nitrogen accumulated in older leaves translocates to younger leaves to solve a deficiency. The result, deficiency and excess symptoms appear on the older, lower leaves first. Immobile nutrientscalcium (Ca), boron (B), chlorine (Cl), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), silicon (Si) and sulfur (S)-do not translocate to new growing areas as needed. They remain deposited in their original place in older leaves. This is the reason deficiency symptoms appear first in the upper, new leaves on top of the plant.

Head this problem off before it gets any worse by flushing the plant containers with three times the volume of water to the volume of soil. For example, pour 9 gallons of water through a 3-gallon container of soil. The water will leach out all the built up nutrients that have accumulated in the soil. Once flushed out, the problem is solved.


how to grow weed

This wall of weed shows how large older leaves turn yellow from a lack of nitrogen during flowering. The purple color is a result of cool 40-degree nighttime temperatures that restrict phosphorus.