Mites and Yellow Leaves
It’s my first time, and I’ve had a li’l friend in my room for over a month. We have spider mites, and I’m pretty sure we got the bad boys. We use Schults insect spray, but the damage to the leaves is terrible. I’m using Miracle-Gro soil and all-purpose 24-8-16 Miracle-Gro food. The bottom leaves are falling off and getting yellow. The neighbor’s cat put a couple of holes in the damaged leaves, too. The seventh set of leaves is growing on top. The overall height is, like, stunted. Help!
The spider mites have to go! First, clean the room well and spray it with disinfectant. Don’t give mites a place to live. Clean off and disinfect containers and the floor, too. Next, smear a line of Tanglefoot around the lip of each container. This will isolate the pests to a specific container. Spray undersides of leaves with aerosol pyrethrum. My favorite is Whitmire’s X-Clude, because the pyrethrum, which generally has only a two-hour life span, is encapsulated. Encapsulation gives the pyrethrum a life of up to 24 hours.
Change fertilizers to a balanced organic blend or a high-quality hydroponic mix. Changing to such a fertilizer will solve many problems quickly. And keep the cat out of the room! Cats are often attracted to cannabis plants because the leaves move. Cats also dig in pots, which disturbs surface roots, and their hair sticks to resinous buds.
More Yellow Leaves
I’m a newbie grower and have selected Power Plant from Dutch Passion to grow first. I am starting them out in a 2’ x 2’ x 5’ grow box. The temperature is 75Â°F to 80Â°F, with humidity slightly above 40%. I use distilled water with SuperThrive and Oxy-Plus, but after almost four weeks the leaves are beginning to turn yellow, starting from the bottom of the plants. The leaves have also developed a slight brown in the veins. I’m using 190 watts of fluoro as my light source. Can you help me save the plants?
Cold Sober Mike
Dear Cold Sober,
Power Plant is an excellent choice for your first garden. It’s a strong grower, but it can be a very heavy feeder. Many growers have reported that it uses a lot of magnesium, and this is what your symptoms indicate. I always recommend 1 cup of fine dolomite lime (calcium and magnesium) per cubic foot of soil to head off this problem. Since you’re growing in a hydroponic system, the fertilizer you’re using doesn’t supply nearly enough nutrients for rapid growth. SuperThrive is a supplement that’s not meant to be used as a fertilizer, and Oxy-Plus is a very mild fertilizer designed to avoid overwatering slow-growing houseplants. Also, the plants aren’t receiving enough light.
Power Plant is one of the main commercial strains in the Netherlands. Growers give it a full fertilizer schedule of good-quality hydroponic nutrients. They also give this sativa-dominant strain plenty of light for highest yields.
Your best bet would be to switch to a 400-watt high-pressure sodium (HPS) lamp and augment it with a compact fluorescent light. This plant really needs a lot of light for the best performance. Also, remember, since it’s sativa-dominant, stretching between the internodes is common when buds are forming. You could easily wind up with plants four feet high or taller. Start bending and build a trellis before buds start to stretch. Less light will make them stretch more.