Be sure the strength is at least 15ppm, preferably 30ppm. Less than 15ppm produces male sacs with little viable pollen.
When sexing begins, male pollen sacs will develop instead of female calyxes and pistils. Male plants mature much faster than females, and viable pollen can be expected within 3–4 weeks once the plant has been sexed. Some growers will spray until the plant shows sexual growth, just to be sure the method has worked. Make sure these plants are well-isolated from any flowering females. A burst pod can release millions of pollen spores, and it only takes one spore per hair to create a seed.
TECHNIQUE 1: COLLOIDAL SILVER
Plants bred using feminization are homozygous. This can have two effects that can’t be assessed until the seeds are grown. Homozygosity will increase the dominant or recessive traits of the parent in the progeny, so features you don’t want and do want can be amplified. Genetics is a weird, weird thing.
Colloidal silver is by far the easiest to source or make. It is non-toxic, non-caustic, and can be bought from a pharmacy or easily online. The other solutions can be dangerous, difficult to get a hold of, and expensive—except gibberellic acid, which can be found in nurseries, but is not as effective as colloidal silver. But if you want to watch some freaky plant growth just for the fun of it, give gibberellic acid a try. It is a growth stimulant and makes plants stretch and stretch.
Spray the plants to be feminized with colloidal silver every day, and three times a day if you can manage. Soak them well. Do this for two weeks, then leave the plants to grow as normal. Some growers report getting results after spraying for only 5–10 days.
Keep a close eye on the temperature and moisture level of the soil to keep the seed happy. It’s very delicate at this stage. Use a spray bottle to water it—over-watering can suffocate and kill the delicate sprout.
Cultivating males is important for breeders trying to cross new strains and genetics, but most people growing for buds will want to remove the males.
Marijuana seeds can be acquired from an array of sources and can vary in quality. For more info on how to buy marijuana seeds, check out our Guide to buying cannabis seeds.
If cannabis is legal in your state, you can buy seeds or clones from a local dispensary, or online through various seed banks.
A seed has germinated once the seed splits and a single sprout appears. The sprout is the taproot, which will become the main stem of the plant, and seeing it is a sign of successful germination.
Check out Johanna’s full video series on how to grow weed on Leafly’s YouTube .
Autoflowers don’t need lots of nutrients because they’re small and don’t spend much time in the vegetative cycle. They won’t need as much veg nutrients—such as nitrogen—but will need more bloom nutrients.