Re-vegging a Flowering Marijuana Plant: Why, When and How

Many a grower has looked upon their prospective harvest, their garden teeming with beautiful, trichome-laden buds ready to bend and snap the branches supporting them, and wondered why the magic must end there. The plants are big, strong, and well-structured, so what is stopping the grower from simply pruning off the buds and forcing the plants back into the vegetative stage? As it turns out, very little. 

Re-vegging, as it is known, is the act of reverting a flowering cannabis plant back into veg conditions, causing it to transition back into vegetative growth. The most significant factor in reverting plants back into vegetative growth is photoperiod, as it is the transition from 18/6 (18 hours on, six hours off) lighting to 12/12 (12 hours on, 12 hours off) lighting that triggers the flowering stage in the first place.

Thus, it is possible to re-veg your plants once they’ve bloomed (or even mid-bloom), though the results may be less than favourable. Understanding why cannabis plants re-veg, when this phenomenon occurs, and how you can control and actually utilize re-vegging in your garden can prove beneficial and help avoid many common mistakes.

Why Re-veg Cannabis Plants?

There are several reasons why growers may choose to re-veg a plant (or plants), some of which include the hope of increased yields, the preservation of a particular lineage or phenotype, or simply the desire to experiment with a second harvest. Some growers may experience accidental re-veg, a phenomenon usually spurred on by unexpected or unintentional changes to the photoperiod. Whether intentional or accidental, re-vegging cannabis plants is always an interesting experiment.

Monster Cropping – One common instance of re-vegging marijuana plants is “monster cropping”, a process during which a grower will cut clones from an already-flowering plant in hopes of increasing yields. Monster cropping involves cloning from the lower branches of a flowering plant (as lower branches have higher concentrations of growth hormones), removing any flowering nodes from the clone, and introducing it into veg lighting (although many growers prefer a 24/0 light cycle while waiting for seedlings and cuttings to root). It is a commonly held belief that monster-cropped clones, once reverted back into vegetative growth, tend to grow bushier, sturdier plants than typical clones. It should be noted, however, that monster-cropped clones often require extensive low-stress training (LST) to help them develop into productive plants.

Preservation of a strain – Occasionally, growers run into the problem of losing genetics, either by lack of preparation or accident. It is not uncommon for growers to begin flowering a particular batch of plants before realizing that, in their haste and excitement, they’ve not cut clones to continue the plant’s lineage. In this case, cuttings or a whole plant may be placed back into veg lighting conditions for the sake of preserving the genetics. Once the plant has successfully re-vegged (a process made quicker and easier by a solid root system), clones may be taken, and the genetics passed on for another generation. The process of re-vegging flowering clones also eliminates the need to keep mother plants on hand, a task that can further bog down amateur growers.

Second harvest – Many novice growers believe that after harvesting the first time, they should be able to prune their plants and harvest a second time. Unfortunately, marijuana is an annual plant, meaning that its life cycle takes place within one year, rather than a perennial, such as apple and stone fruit trees, which produce a new crop each year. Therefore, while it is possible to trick the plant into thinking it is experiencing another spring by increasing the hours of light it receives from your grow lights, it should be noted that this is not the natural growth pattern of cannabis. As a result, second harvests brought about by re-vegging a harvested plant tend to be diminished, producing decreased yields and light, airy buds, despite the plant’s fuller, bushier appearance. In addition, plants tend to take a while (up to ten days) before reverting fully back to the vegetative phase, often leaving the grower wondering if anything will happen at all. Sometimes it doesn’t, another of the assumed risks of intentionally re-vegging your plants.

Sexing plants – When growing with regular (as opposed to feminized) cannabis seeds, it is necessary to determine the sex of a plant before forcing it into the bloom cycle. Sex characteristics in many strains can remain undeveloped until flowering begins, creating a unique conundrum for growers. Rather than risking a male plant flowering in their grow room and being forced to remove it, many growers opt to “pre-flower” their plants to determine the sex. This involves placing young plants under a flowering light schedule and allowing them to develop sex characteristics. Once the sex of the plant has been determined, females can then be re-vegged to further develop foliage and mature into the desired size before flowering.

Not all re-vegging is intentional. Much to their dismay, many growers have experienced accidental re-vegging of already-flowering plants. Accidental re-vegging typically occurs for one of a few reasons, such as faulty light timers which alter the plant’s light cycle, a light leak in a tent or grow room (allowing light in during the plant’s dark period), or an outdoor crop being planted too early in the year.

When Should You Re-veg Marijuana Plants?

There are few instances when re-vegging your plants will prove fruitful, productive, or necessary. The fact remains that re-vegging flowering plants can be tedious and tricky, as proper care and handling of clones involves proper sanitation, attention to detail, and patience, all factors which can prove difficult for beginner growers.

Additionally, clones don’t always root, which can be frustrating to a new grower. Re-vegging plants is typically a process left to growers operating larger operations with lots of available resources to maintain a consistent growth cycle. Care of monster-cropped clones can prove a tedious and challenging task as well, one which may be best left to experienced cannabis growers.

Another determining factor in deciding whether or not to re-veg is a grower’s circumstances. Understandably, throughout the length of a full grow cycle, a grower’s work or living circumstances may change, forcing a move. If a grower’s garden is already a week or two into its bloom cycle, this can pose some obvious problems.

Once the plants have been moved, depending upon their degree of shock from lack of light, transplant, or other disturbance, it may be necessary to place them back under 18/6 lighting to re-establish root structure and overall plant health. This may be particularly useful if the plant’s flowers have been significantly affected or damaged by the move.

How to Re-Veg a Flowering Plant

Re-vegging a plant is really as simple as placing the plant back under the proper lighting conditions to trigger vegetative growth. In most instances, this means an 18/6 light cycle, though, in the case of clones and some badly damaged plants (such as following a harvest), 24/0 may be more appropriate.

The first signs of re-vegged growth emerge slowly, typically taking between 10-14 days. New growth on re-vegged plants tends to be ugly and malformed at first, with leaves appearing rounded and smooth. It may take multiple weeks before recognizable, normal foliage begins to develop.

Once a re-vegged plant has developed established roots, it tends to grow bushier than normal. This makes re-vegged plants prime candidates for many plant training techniques, such as SCROG (Screen of Green) training and bending. Monster-cropped clones, especially, tend to develop into large, many-branched plants capable of supporting a decent harvest.

While re-vegging may not be suited to your particular cannabis grow, it is undoubtedly an interesting and fascinating phenomenon. It can be fruitful and productive for some growers and in some situations, but by and large, most small-scale growers find it easier to begin new plants from seed or cut clones from a mother plant.