Revegging, or re-vegging, means pushing a cannabis plant that has started or finished flowering back into vegetative growth. Growers do it on purpose to save a plant after harvest or to keep a valuable genetic. It also happens by accident when a flowering plant gets long days or light during its dark period. It works because photoperiod cannabis needs continuous long nights to keep flowering. Take the long nights away and the plant slowly returns to leafy growth, though the new growth often looks different from its first veg. The price is several weeks of lost time, extra stress and a smaller second harvest.
Why a flowering plant can go back
A 2024 study explains what happens inside the plant. Short days keep the levels of two growth hormones, gibberellin and auxin, low in the shoot tip. This allows the tight branching and short internodes that make a dense bud. When plants were returned to long days, those hormone levels rose. The internodes inside the flower cluster stretched, the cluster broke apart, and the plant went back to its long-day growth pattern.
The key finding: commitment to flowering does not persist. The plant needs continuous short days to keep building buds. That is the basis of both deliberate and accidental reveg.
Deliberate reveg after harvest
A Vietnamese grow handbook describes the method, often called regeneration.
- Harvest carefully. Cut the main buds, but keep most of the healthy green leaves, especially in the middle of the plant. On the lower branches, leave several small buds. These leaves and small buds are what will turn green and grow again.
- Trim and refresh the roots. The handbook cuts back the root ball on four sides and the bottom, then repots with fresh soil around it. A rooting stimulant can help after root pruning.
- Give long days. Place the plant under 18 hours of light and 6 hours of darkness, or outdoors in long natural days.
- Wait. It takes about 7 to 14 days for the plant to register the change and switch to vegetative growth. Unlike a normal plant, the lower branches usually sprout first.
- Regrow. Let it grow in veg for about 30 days. Then switch to 12/12 for a second harvest, take cuttings, or keep it as a mother.
In the handbook’s example, new leaves appeared 7 days after harvest and new branches after 15 days.
Growers who have tried it report that the second harvest is only about half of the first. The plant must be healthy. Indoors, any pests or disease from the first cycle come back with it.
Reveg to keep a genetic
The better way to keep a genetic is not to need reveg at all. One grow book advises keeping a few mother plants in veg as a clone source. Clones can be taken from a plant up to two weeks into flowering. But these clones go through shock when they return to vegetative growth and often root poorly.
The same book discusses sexing plants by flowering them and then returning them to long light. Males showed their sex after about two weeks of 12/12 and went back to vegetative growth about a week after returning to 24-hour light. The book still advises flowering a clone instead, because making the plant revert causes unnecessary stress and interrupts growth.
Accidental reveg
Most accidental reveg comes from light at the wrong time.
- Indoor light leaks. Grow books warn that any light during the dark period can break the flowering signal: a flashlight, a desk lamp shining into the tent, even small LED indicators. Check the room from inside in full darkness.
- Night lights outdoors. Greenhouse growers deliberately keep short-day crops vegetative with a short burst of light during the night. A street light, security light or porch light shining on a plant can have the same effect by accident.
- Moving a flowering plant into long days. The handbook’s second-harvest method relies on exactly this: an indoor plant harvested in late spring goes outside into long summer days and regrows.
In the tropics, natural day length stays short, so accidental reveg there is more likely to come from artificial light at night than from the season.
How to tell a plant is revegging
- New leaves with fewer leaflets. Small leaves with a single blade, or with only three blades, appear at the tips. This mirrors seedling growth, where the first true leaves have one blade and later ones have three, five, seven and more.
- Leaves growing out of the buds. In the 2024 study, plants that had flowered for 15 days showed simple leaves at the top of the flower cluster about 13 days after returning to long days.
- Buds loosening. Internodes stretch inside the cluster, splitting it into single flowers.
- New shoots from bud sites. Plants that had flowered longer took longer to show new leaves, but eventually grew new shoots out of the old flower clusters.
Revegging an autoflower
Changing the light schedule does not work on autoflowers. They are photoperiod-insensitive, and autoflowering cultivars in research flowered even under continuous light. Light is not what controls their flowering, so extra light will not send them back to veg.
Risks
| Risk | Why it matters |
|---|---|
| Lost time | Weeks of waiting before normal growth resumes |
| Lower yield | Second harvest reported at about half the first |
| Stress | Grow books link light disruption to hermaphrodite risk |
| Pests and disease | Problems from the first cycle carry over |
| Odd growth | Irregular leaves and branching for a while |
Common mistakes
- Stripping every leaf and bud at harvest. The plant needs green leaves and small buds to regrow.
- Expecting instant results. The first week often shows nothing.
- Revegging a sick plant. Only healthy plants reveg well.
- Ignoring stray light. Accidental reveg in a flowering room ruins a crop. Find the leak.
- Trying it on autoflowers. Light changes do not reset them.