Jennifer Martin, of cannabis consultancy Marijuana Propagation, spoke on “Plant Health Management for Optimal Quality and Yields” at the CannaGrow Expo, May 7, at the Paradise Point Resort and Spa in San Diego. Here are a few key takeaways from her presentation:
-Sick plants do better with less light and water until they heal. In general, said Martin, if plants are sick and/or yellowest under the brightest area of light, raise the light. “I see a lot of happy plants under less light,” she said. “I always pull the light intensity for unhealthy plants.”
-Ideal temperatures for flowering rooms range from 70 to 75 degrees, and 75 to 83 degrees for veg rooms. If you’re using LEDs, the ideal temperature is 83 degrees, and 79 to 80 degrees for high-pressure sodium (HPS) lights.
-Plants need lots of circulating air around them. “Plants have to stay moving and pruned, so you don’t have bunched up areas,” she said. It is ideal to have circulating fans every 8 feet or so. Martin noted that there are now tables out on the market with fans blowing air up, “which is a pretty cool thing,” she said.
-pH range is the first thing to check when there is a problem your cannabis plants are sick. The ideal pH zone is 5.7 to 6.3, she said, and 5.9 to 6.0 is where she has gotten the best results. Second to pH is food excess, she added.
-Martin said she always “looks for nutrients with less phosphorous and nitrogen, because there is usually more than a plant needs” in many synthetic nutrients. Synthetic fertilizers also tend to have high sulfur and chloride by design, she added, but “fortunately both are fairly flushable.” There are pros and cons to both synthetic and organic nutrients, but it’s more rare for “people to [grow using synthetics] properly, she said. “They tend to over-fertilize.”
-In general, Martin said,, “avoid excess variables” in your cultivation practices, and keep things simple.
