How to re-veg marijuana plants

What is re-vegging?

Cannabis is an annual flowering plant, its life cycle limited to just one season. In the wild, it grows from a seed, flowers, and dies, all between spring and fall. Once a female plant dies, it will drop seeds, which are responsible for carrying genes through to the next growing season.

But it’s possible to hack this process to give cannabis plants a second growing season. A grower can manipulate a plant and force it to revert from the flowering stage back to the vegetative stage again. This process is known as re-vegging, or regeneration, and it allows you to harvest buds from a plant, then grow the same plant again for a second harvest of buds.

Cannabis has a short-day photoperiod, meaning it transitions from a vegetative period to a flowering period—when it starts growing buds—because the amount of light it receives reduces. This happens outdoors as autumn approaches and days become shorter. Indoors, growers “flip” weed plants into the flowering stage by manually reducing the amount of light they get each day. 

Altering a cannabis plant’s photoperiod schedule after harvest will allow you to re-veg it.

Benefits of re-vegging cannabis plants

Reduce vegetative periods

A cannabis plant that has undergone a full growing season will have a complex and robust root system. If re-vegging a weed plant, it will move through its second vegetative phase quicker if it has a mature root system, whereas clones or seeds will take longer to establish roots.

Eliminate mother plants

Growers will sometimes keep mother plants, which are plants that always stay in the vegetative stage for the purpose of cloning only. But keeping mother plants takes time and space. Re-vegging allows you to get rid of mother plants, freeing up space in your grow for plants that only produce buds. It also saves time and resources, as you won’t have to tend to mother plants.

Increase yields

The process of taking a clone from a flowering plant is a re-vegging technique known as “monster cropping” (more below), and it can produce more vigorous and bushier plants. If done correctly, monster-cropped clones have the potential to create plants with higher yields the second time around because of an increased vegetative mass, stronger stems and branches, and more nodes for potential buds.

Cloning/Preserving a phenotype

If cloning a weed plant, growers usually need to take a clone of a plant before it begins flowering. But if a grower neglects to for any reason, that phenotype, or the genes of that specific plant, will get lost. Re-vegging is the only way to preserve an exact replica of a particular phenotype once it has transitioned into the flowering state.

Disadvantages of re-vegging cannabis plants

Difficulty

Re-vegging is hard to successfully pull off, even for seasoned growers. It takes a few weeks for new growth to appear so you might be wasting time and space waiting for new growth only for it to not happen.

Smaller yields

Most growers who re-veg say that yields decrease the second time around. So while re-vegging may cut down on the amount of time it takes to grow a plant, it might not produce as much.

Stress on the plant

The re-vegging process is highly stressful on a plant and even if it does re-veg successfully, aberrations often occur, such as unusual leaf growth and hermaphroditism. Re-vegged plants are more delicate and must be given more attention and care.

Types of re-vegging

There are a few ways a cannabis plant can revert from its flowering stage back to a vegetative stage.

Post-harvest re-vegging

Probably the easiest method, this will allow you to harvest a plant for buds and then re-veg it for a second growing season. This is typically done with indoor plants, as you’ll need to control the amount of light they receive.

How to:

When harvesting a weed plant, leave a few healthy buds and branches intact at the base of the plant. Reset the plant’s photoperiod back to a vegetative schedule: 18 hours of light/6 hours of dark a day (as opposed to the 12 light/12 dark schedule it had when flowering).

Also, change the plant’s nutrient regimen, giving it nutrients more conducive to early-stage growth. It will need more nitrogen for root and leaf development, as opposed to the high amounts of potassium and phosphorus it likely received during flowering.

Post-harvest re-vegged cannabis plants often take a little bit of time to take off at first and some strains may not even be receptive to this method at all. Early growth on a re-vegged plant may exhibit stress-induced mutations like single-fingered leaves and odd node patterning, but these issues should go away after a few weeks if re-vegging is successful. Plants that re-veg successfully can display increased vigor after the initial transition.

Monster-cropping clones

As mentioned above, cloning a plant while it’s in the flowering stage is called monster cropping. To successfully do this, take clones from the lower branches of a plant when it’s in the second or third week of flowering.

How to:

Take a clone as you normally would, but be sure to remove all visible flowering nodes from each clone. This will improve the clone’s ability to root out by halting flower production within the cutting.

As with post-harvest re-vegging, monster cropping may result in stunted and mutated growth at first, but with proper care and training, this method can produce massive plants with increased vigor and foliage growth.

Accidental re-vegging

Cannabis plants will unexpectedly revert back to vegetative growth if there is a disturbance in their photoperiod schedule—for example, if they receive 12 hours of light a day for a while, and then start to get more than that. 

This can occur both indoors and outdoors, usually because of a light leak or a light timer malfunction when growing indoors, or from planting outside too early in the season when growing outdoors.

Even the tiniest of changes in a cannabis plant’s light cycle can cause it to flip back to a vegetative state, and some plants may even turn hermaphroditic, growing both male pollen sacs and female flowers.

Patrick Bennett contributed to this article.

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