Home Articles Diagnose Your Weed: Here Is How

Diagnose Your Weed: Here Is How

Although growing cannabis could be quite a breeze, you might sometimes run into certain growing problems. Even if you apply the best gardening practices, you might still experience some minor issues. 

Cannabis is a very resilient plant and can survive in harsh environments and battle pests. This gives you all the time that you need to figure out what is wrong and how to go about correcting it. 

Diagnosing a cannabis plant problem could be pretty complicated at times – especially if you’re just starting out. However, by looking out for certain symptoms on the leaves, you can get a diagnosis fairly quickly. And provided you have the right diagnosis, you can find a solution rapidly.

 Here are some of the most common symptoms that you should look out for. 

Yellow or Pale Green Leaves 

When the leaves on your cannabis plants begin to turn yellow, it’s usually because of a nutrient deficiency. Pinpointing the part of the plant that is yellowing could help you figure out the problem accurately. 

  • Yellowing At Top Of Leaves

If the yellowing is at the top of the plant, it could be as a result of light bleaching or a nutrient deficiency of either iron or sulfur.

  • Yellowing At Bottom Of Leaves

If the yellowing is at the bottom of the plant, the light is either not extending to that part of it would be a nitrogen deficiency.

  • New Growth Turning Yellow

This is a clear indication that your plant is experiencing nutritional deficiencies. It could either be the nutrient content of the medium being low or the pH level being off balance. If you are growing with soil, you should either transplant or add nutrients to the medium. 

  • Yellowing of Leaf Veins

If the veins of your cannabis plants are turning yellow but the rest of the leaves remain green, this could be a result of a calcium or magnesium deficiency. Calcium and magnesium work together so they need to present always. 

Purple Stems and Branches

This should not be much of a bother because it could be a normal genetic trait displayed by that particular cannabis plant. But here are some other reasons why you may get purple stems and branches. 

  • Temperature

If your plants get too cold, it would typically release some hormones to protect itself. These hormones would then make secrete a purple pigment. This is also how purple buds come about. 

  • Nutrient Deficiency

If your plant is deficient in nutrients like Magnesium and Phosphorus, this could lead to a display of purple stems and branches. It could also be as a result of incorrect pH levels. 

  • LED Lighting

Using many “Blurple” LED lights would eventually cause your plant to bleach and turn purple. If you notice your plants turning purple, check the part that is shaded from the light. If you find out that the other part is green, then it is most likely a case of light bleaching. 

Leaf Spots

Leaf spots on your cannabis leaves could be as a result of many different reasons. It could be as a result of nutrient imbalances, bugs or the plants getting burnt by light after they have been foliar fed. 

In order to diagnose a plant problem using spots, you should, first of all, ensure that there are no bugs present. 

Furthermore, you should look under the leaves where the spots are because if bugs are the cause, they would be hiding underneath the leaves. 

  • Orange or Rusty Spots

Orange or rusty spots present on cannabis leaves can be caused by a calcium or phosphorus deficiency. 

The difference between a calcium deficiency and a phosphorus deficiency is that while a calcium deficiency would show relatively smaller spots than phosphorus and phosphorus also displays patches rather than spots. 

In addition, certain bugs like spider mites and thrips may cause orange or rusty patches on the leaves. You could check underneath the leaves for eggs. 

  • White Dots

White dots on cannabis leaves are a very clear sign of mites. These small insects bite the leaves and suck their juices then leave behind tiny yellow or white dots. 

  • Dark Purple/ Black Patches on Cannabis Plant Leaves

Phosphorus deficiency is the only cause of purple or black blotches on the middle and lower leaves on the cannabis plant. Purple blotches clearly imply the fact that yield is already being affected.

  • Silvery “Spit like” Patches

Silvery patches like this are an indication of the presence of thrips. They usually pierce the plant’s leaves and then lay eggs into them. This makes the patch resemble a snail trail or dry spit. 

  • White Powder on Cannabis Leaves

White powder on cannabis leaves can only be as a result of powdery mildew or nutrient splashback. While feeding your plants with foliar feed or splashing nutrients on the leaves, the salt would become fine white powder after the water dries up. This can be rinsed off very easily. 

However, for powdery mildew, you might need to get rid of the entire plant. Powdery mildew is a mold that can grow on your plant and given the right conditions, the spores will germinate and can infect your entire grow room. 



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