Green Algae & Powdery Mildew When Growing Cannabis

When growing cannabis, green algae is a slimy algae that needs nutrient, light and the moisture from the growing medium. Luckily, it causes very little damage but attracts other pests to eat on it and they will eventually attack the cannabis plants.

You can prevent green algae by covering the growing medium to prevent light from contacting them or run an algaecide in the nutrient solution to kill them off when growing cannabis.

Growing Cannabis w/ Powdery Mildew Issues

Powdery mildew first shows small spots on the tops of leaves, so that’s the first place you want to look! Once you see powdery mildew on the cannabis plant’s leaves, this means the disease has been inside of the plant for a week or more and spreading.

Powdery mildew slows plant growth, leaves turn yellow and plants die as the disease advances. It has a look that is a fine, pale-gray on the white powdery coating on leaves, shots and stems so you will learn that cleanliness is the best prevention when growing cannabis.

Here are some recommendations for growing cannabis:

  • Prevent powdery mildew by avoiding cool, damp, humid and dim grow conditions
  • Increase the air circulation and ventilation to cool the room and reduce humidity
  • Make sure there is space in-between the cannabis plants so they aren’t touching each other
  • Remove contaminated leaves and plant parts
  • Avoid using too much nitrogen fertilizer

You can spray plants with copper and sulfur-lime sprays to help with these issues. A saturation of baking soda spray dries out to powder on the leaf and changes the pH on the leaf to 7.0, making sure the powdery mildew isn’t able to grow.

You can also use a biological control of Bacillus subtilis to the soil when planting.

Let us know what you think.