Connect with us


Grow Q&A: Why Are My Cannabis Clones Moldy?



Dear Dan,
I’m having a hard time with my clones.  I am using two gallons of distilled water with a little bit of Superthrive, and after 8 to 10 days I get this white mucus on the cut ends. The water temperature is 75 to 78 degrees, and I’m running the misting pump 24 hours a day. I need help! This is my second try and I lost them all on the first due to this ugly fungus. — Tom S. 

Dear Tom,

The water temperature in your cloner is too high. You need to bring the water temperature down to between 65 and 70 degrees with 65 as the ideal. If the temperature is too low, it will shock the plants. Too high and the dissolved oxygen levels decrease dramatically—and Pythium (mold) can and will become a serious issue.

Lowering the temperature of your nutrient solution can be accomplished in a number of ways. Some cloners come with the pump on the outside and this can reduce heat as well. Sometimes, moving a cloner out of a warm growroom under HID (High Intensity Discharge) lighting and into a cooler space with a fluorescent or LED light system can cool the water as well. Painting a dark-colored reservoir with a lighter color on the outside also decreases the amount of heat absorbed.

You may have to bite the bullet and invest some money into a water chiller. They come in a variety of prices and sizes to handle different reservoirs so you have to find the right one for you to dial in the temperature to exactly where you want it on the digital display.

A cheap but temporary alternative is to freeze a 2-liter bottle of water and chuck it into your reservoir. Bear in mind that this is not a long term solution and is a relatively crude and inaccurate way to accomplish cooler nutrient solution temperatures with consistency.

Don’t miss our previous Grow Q&A: My Pot Seeds Sprouted! Now What?