On Growing: Clone The Right Way

On Growing: Clone The Right Way

May 3, 2020

On Growing is written by home-growing enthusiasts and professionals in the industry, with advice for today's DIY gardener. This month, Rhett Thompson, former dispensary manager and long-time grower, shares his method for cloning, first forged and tested in a small apartment closet.

What I like best about cloning--as opposed to growing from seed--is that it shortens your grow cycle significantly, up to 4 weeks, or even more. The one downside--often debated among growers--is that significant degenerative changes (essentially, weakening) can occur as you continue to take clones from clones, from clones and so-on. When this begins, growers may notice thinner, more spindly branches, or plants with a higher susceptibility to bugs, mildew or mold where there was no problem before -- all of which will eventually lead to a smaller harvest -- ultimately signaling that it’s time to start from seed again. 

So remember: the healthier the plant that you clone from & the quicker your clones take root, the more likely you will have robust plantlings and awesome harvests for generations to come. That said, let's take a step back and review a quick and easy cloning method, a sure-fire way to preserve those long-perfected or hard-to-find genetics you have in your garden.

Step #1. Select your mother plant. I recommend keeping mothers separately in perpetual (ongoing) vegetative state and taking the cuttings you intend to root from there. This prevents your variety from degenerating, and allows constant clones at the ready. If you can’t do this - don’t worry. I used to cut clones right before the flowering stage, and successfully harvested clones from clones, time after time, with great outcome.

Step #2. Put your cloning kit together. I prefer using rooting powder instead of gel; you get more bang for your buck and it’s just as effective (just be careful not to breath it in!). For rooting medium, grab some all-natural grow plugs made with composted tree bark; they're biodegradable and hold far less water than rockwool, making it easier to control your moisture levels, especially for beginners. They can also be used for both soil & soilless set-ups. Buy a cheap propagation dome (or make your own - I made my first one in college out of a wire hanger and a plastic grocery bag) and some new razor blades for all your cuts. For lighting, you only really need one or two cheap compact fluorescent “daylight” bulbs so they have somewhere to stretch toward. Too much light at this stage can be detrimental.

Step #3. Get set up. On a table, line up your open rooting power, bowl/or small bucket of water, a plate filled with about 1cm of water, and razor blades. Open the plugs and use a small nail to enlarge each hole to about a skittle-size in width, and 1-2 inch deep (a little more than halfway). Then put them in the bucket of water. When completely saturated, squeeze out slightly to reduce wetness to about ¾ water capacity, and place each evenly on the tray of your dome. Take mental note of how heavy the cube is at this point. Make sure there’s no standing water in the tray after placing them.

Step #4.  It's important to use a healthy shoot toward the bottom of the mother plant as they're more nutrient-rich due to gravity, and produce roots much faster (plus, if you take cuttings right before flowering, it’s not always a great idea to prune where you top cola’s will be). Cut the branch (or section of a branch) off, keeping the snips around 4in long.

Step #5.  Clip off any leaves lower than 3in, and submerge stem in the plate of water. At a 45 degree angle, carefully recut the stem about a centimeter upward at its end, making sure to cut it underwater. This keeps air bubbles out of the stem, which can kill the cutting.

Step #5. “Scuff” up the stem lightly with the razor, scraping it along the sides, an inch up. Be gentle. This will allow more surface area for the powder to work. Dip the stem into the powder liberally, and place into a plug. Typically I repeat at least twice to make sure the powder reaches all the way to the bottom of the hole, using the cutting itself to push the excess inside.

Step #6. Repeat for each clone. Then cover dome, and place in a warm room under your bulbs. If the room is warm enough, your dome should fog up within 2-4 hours. If it doesn’t, move to a warmer area. Check daily but don’t open unless you’re planning on re-saturating the plugs. To do this, take a glass of water, and carefully submerge cube about ¾ of the way until it feels almost as heavy as when you first took your clones.

And that’s it! They should root relatively quickly- within 5 days - if your conditions are right. Otherwise, they could take up to 2 weeks (or not at all). Avoid overwatering - this will rot the stem. If in doubt, error on the side of underwatering. You will be able to tell when your cubes are dry by look & touch but don’t base your judgements solely on the fog level of the dome.