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The Art of Re-Vegging Cannabis Plants to Save Space

By Jennifer Martin | Last updated: April 22, 2021
Key Takeaways

Fear not if you’re tight on growroom space but want to clone some of your best plants. Re-vegging is a technique that will help create great clones and save precious space in your facility or grow area.

Are your cloning results dependable? Are you short on space but interested in phenotype hunting for new production stock? Then re-vegging is for you! This article will fine-tune your planning and skills for reliably reproducing your favorite new cultivars.

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Re-vegging is the process of reverting a flowering plant back to foliage production, or to the “veg” stage of growth. The main reason to “re-veg” a plant is because it allows you to preserve a special flowering cultivar from which new vegetative mother plants can be made.

Those of you with more time and space will understandably stick with the status quo, which is to cut a few clones from all your teenage female seedlings before they’ve ever flowered, then flower those teenage seedlings you’ve just taken clones from, assess their quality, and only keep the now-rooted progeny of the best flower producers. The big downside of this method is the considerable amount of time, and especially space, it takes to pot the clones and care for them for the six weeks it might take to determine their value as their flowering mother develops. And all this knowing 95 per cent or more of them will be destroyed, since great new phenos are quite rare to find.

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Bigger facilities with plenty of space do very little re-vegging because, for the preservation of a potentially valuable cultivar, it’s fundamentally more reliable to cut clones from it before it has ever flowered. This method also has the advantage of getting you up to full production on new cultivars a couple months sooner than re-vegging can do. It’s standard practice to take at least four clones from each prospective mother, assuming as a worse-case scenario that only one of the four survives. Labeling them accurately is critical. If, for example, you sprouted 10 feminized Huckleberry Soda seeds, you’d label each seedling and the four clones taken from it as HS1 (you’d have five HS1s in this case — the original seedling and the four clones cut from it), HS2, HS3, up to HS10. Your HS3 seedling might turn out to be the best flowering plant, in which case you’d discard all of the HS clones except for the four HS3s. Those four HS3s would become mother plants, and you’d propagate out your stock from there.

Re-Vegged Cannabis Plant

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Cloning and Saving Canopy Space

For those of us who are always looking to optimize canopy space, and we fashion ourselves as pretty good cloners, re-vegging is a more attractive option than cutting all those mostly doomed clones we discussed above. In this case, you put your female seedlings straight into flower without cloning them first, knowing you can clone the flowering plant once you determine its value and revert those rooted flowering clones back to vegetative growth for further propagation. Yes, this takes two months longer in the end, but the delay isn’t usually a problem because growers already have other cultivars in production and aren’t in a hurry to rotate in new stock, as much as they prefer saving cloning and vegetative cultivation space.

Okay, because we’ve decided we are comfortable rooting flowering clones, we will label and flower all of the female seedlings without cloning them first, knowing we can clone from the flowering plants once we identify the keepers. The keepers start showing themselves as early as four weeks into flower, but six weeks is more realistic for most of them. Within six weeks, you will see how stretchy the plant is going to be, if it’s got above average resin content, above average smell, strong flower formation, good vigor, strong branches, etc. You’ll know if it’s special to you and works with your cultivation method. At that point, you can cut two to four clones from the bottom of the plant. Be careful not to go overboard with lower branch pruning in the early weeks so you’ll have enough clones to choose from. It’s much better to choose lower branches because, with their smaller flowers, they revert more quickly back to vegetative growth, and because smaller flower clusters are less likely to get moldy when they are rooting under humidity domes.

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If you have no choice, you can clone a branch with bigger, more mature flowers, but in this case you have to be really careful about the humidity levels inside the dome and modest watering levels in the media during rooting because bigger flower branches, when sitting still without roots, are very prone to rot. All in all, the sooner you identify your favorite cultivars from the flowering seedlings, the better, so you can more quickly and effectively root a few branches from them and start re-vegging the successful ones. The most common time for me to cut clones from the lower parts of flowering plants is in week five of flower, but sometimes a keeper takes longer to show itself, in which case I cut clones as late into the flower cycle as it takes. If the clones fail, there’s one last chance to re-veg that cultivar by taking the whole plant and putting it back in the veg room without any cloning. This can be done at any time up to harvest. You can even harvest the best flowers from the plant and leave some lower shoots and leaves that will be sufficient for re-vegging.

Trimming a re-vegged cannabis plant

Rooting Flowering Clones

If you decide to clone from the flowering plant, you can treat those clones almost exactly like regular clones. That means using low light, around 50-75 PPFD, 80°F root zone, 24 hours of light, moderate moisture levels in the plugs or stonewool, and maintaining medium-high moisture levels (minimal condensation) in the humidity dome. You’ll see roots in 8-12 days and can then plant those clones in bigger cubes or pots.

Re-vegging the Entire Plant

If cloning flowering branches has not worked out, you can re-veg the entire plant, in which case it’s common to cut all of the best flowers off the top of the plant and leave enough growth at the bottom to re-veg. Just a few leaves and grow shoots is enough, although more is better. Just put the whole plant back into 20-24 hours per day of light and wait.

This is where it gets interesting. You’ve basically just put a flowering plant back into veg, but it’s not going to grow like a regular vegetative plant. It will sit there for about a month in what seems like a state of confusion. Because it’s not producing new biomass or getting bigger, you should maintain low levels of light, water, and nutrients. It’s easy to overwater and overfeed transitioning plants, and this is probably the most common step of the re-vegging process that growers get wrong.

Ask a Grower: Why am I seeing seeds in the buds of my cannabis plants?

Think of keeping the plant in a comfortable cozy kind of environmental homeostasis while it reprograms itself for veg growth. Four to five weeks into it, just when you’ve begun to lose hope, you’ll see new veg growth coming out from one of the flower clusters. It’ll be a tiny little sprout emerging from a random place. Now you’ve succeeded at re-vegging, but you aren’t out of the woods yet. The plant still needs gentle light, food, and water until the new growth really takes off. As the foliage emerges, you can cut back any remaining flower material on the plant since it remains susceptible to rot, given that it’s an increasingly old and moist flower cluster.

After you see several new vegetative leaves and branches, you can clone the re-vegged plant to make new mothers. Some growers might try to turn the re-vegged plant itself into a mother, but I have found that re-vegged plants commonly have odd leaf patterns and branch structure. Thus, I prefer waiting until a few normal branches emerge and taking those as clones that will become the future mother stock for that cultivar.

Growers can be very creative, and so I’ll finish by saying it’s unusual, but not impossible, to actually re-flower your re-vegged plant. This has come up for me when I want to run the cultivar through a second flower test as quickly as possible. If I have cut a few good clones from the re-vegged plant and thus secured my mother stock, I can take the weirdly shaped re-vegged plant and put it back into flower while its clones are rooting and get another quick chance to see if it’s the awesome flowering plant I thought it was the first time. You’ll see some cultivars responding better to this type of whiplash treatment than others, but barring some kind of disease or nutrient problem, it should work out ok.

Read next: What are the Best pH Levels for Growing Cannabis?

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Written by Jennifer Martin | Cannabis Cultivation Consultant

Profile Picture of Jennifer Martin

Jennifer Martin is an indoor cultivation consultant who specializes in custom nutrients, propagation, and vertical LED facility design. She is the winner of the 1998 Bay Area Cannabis Cup and currently advises and educates cultivators on the West Coast and in Hawaii. She can be reached at marijuanapropagation.com

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