Collected Q&A from Readers’ Emails, Part 4

Forced Intersexing

1. I currently have a strain that I can’t get any seeds of. Can I intentionally hermaphrodite a female into producing seeds so I can carry on this linage or will the seeds produce hermies as well since technically that’s what I’d be cloning?

Cannabis exhibits a high degree of sex lability, meaning that it easily changes sex under stressful conditions. Since cannabis sexual expression is only poorly understood, we don’t know why this is. This tendency to change sexes is predicted in plants that have evolved dioecy (sexes on separate plants) from monoecy (both sexes on the same plant), which, it is suspected, describes the evolution of cannabis. Furthermore, in cannabis the Y chromosome is genetically inactive; it functions only to replace an X. According to Clarke and Merlin (Cannabis Evolution and Ethnobotany), this system is present in naturally hermaphroditic plants, too, so it appears that cannabis is still “working out the bugs” in the sex determination department.

For whatever reason, once set, the sexual expression of a cannabis plant is not permanent (but the genes are). What I can tell you from my experience is that once you have stressed a plant to the point of inducing it to change sex, a kind of “switch” seems to flip that makes subsequent sex expression a bit of a mess. In other words, I think this is a bad idea. I also think this is why feminized seed production produces so many hermaphrodites, because what you are proposing to do is exactly how feminized seeds are produced. Can you do it? Yes, but you will forever be on the lookout for male inflorescences—and you will never be able to find them all.

So what can you do instead? There are two solutions as I see it; 1) take a cutting and either give it to a friend while you take a break and then retrieve a cut from that cutting when you’re ready to grow again, or, root it in agar and put it in the refrigerator until you are ready to grow again; 2) cross it with a good, known male and put up with some genetic variance in the resulting generation. It will produce many plants much like itself and probably even some better ones (because outcrossed plants tend to do this—a phenomenon called heterosis, or “hybrid vigor”).

Live Plant Potency Test

2. Is it possible to test a live plant for potency? If so, how would I do that?

I put your question to the experts at CannLabs, in Colorado. Here’ what they had to say:

“Yes, it is possible to test a live plant for potency. Due to the high moisture content of an uncured plant the total [cannabinoid] content will be lower than a fully cured plant sample. Many growers test live plants to find out the ratio of different cannabinoids present, as the ratio will not change as significantly as the [total] content and also to find out if there are any specific cannabinoids present, such as CBD.”

Finally, I should point out that for your plant’s cannabinoids to become psychoactive, they must be decarboxylated—that means dried and heated/combusted.

Feeding in Hydro vs. Soil

3. I’ve been growing in a hydro system, but am considering switching to soil. Can I use the same nutrient feeding schedule in soil as I do in hydro or is there anything I should do differently when I make the transition?

No, you don’t have to feed if you choose a quality soil. In fact, this is the single most common mistake I encounter with new growers.

Very important: Resist the urge to feed when growing in soil!

The nutrient will accumulate, toxify the soil and you will be disappointed when you end up with spotted, crinkling leaves on a stunted plant. Do not “fertigate” (this is when you use low levels every time you water). Do not use compost teas except maybe once or twice at the outset to introduce beneficial bacteria (and use it fresh, well-aerated and never old). Fertigation and frequent use of compost teas will eventually cause a pH crisis. I will even go this far: if or when your plants do eventually show signs of soil nutrient depletion, simply potting them up into more soil is the easiest and safest fix. Finally, to ensure good drainage, make sure you place and inch or two of rock at the bottom of your pot.

Dirt From Outside is Dirty

4. If I’m growing indoors, can’t I just use dirt from outside instead of having to buy soil from a grow store?

You can, but you will be introducing a lot of pathogens into your grow room. When you introduce a pathogen that is being held in check in one environment and place it into a new environment where conditions are more favorable to it, it will flourish and you will be left dealing with the disease it causes. You don’t want that. You could go through the hassle of pasteurizing your soil by heating it, but by this time, you’d be better off having bought a quality product in a bag (not to mention, your house and oven will reek of earth for days when you’re done—I’ve tried this). Bagged soil is not sterile, but it is usually pasteurized from composting and it is always much cleaner than soil dug from outside, plus, if it is from a reputable and competent mixer it will have been balanced to provide the nutrients your plant needs. There are no such guarantees from dug soil, which will almost certainly be of questionable quality and nutrient profile.

Best pH Tester

5. I don’t have a lot of money to spend. Which pH tester is best on a $100 budget?

My favorite pH tester costs $50 and is branded “Sunleaves Essential.” There’s no reason for this and I’m not being paid to plug this product, it just happened to be the cheapest one I could find on the rack with temperature compensation and that was waterproof (you will dunk it eventually). It has served me well. I owned a hydro shop for a few years and didn’t have many of these come back. So that’s my recommendation: any pen that is cheap, has temperature compensation, and is waterproof.

Author’s Note: These questions originally appeared in my column in the October issue of Sativa Magazine.

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