Most cannabis plants live one life: sprout, veg, flower, harvest, compost. But cannabis is a photoperiod-responsive annual — not a genetically programmed annual. It flowers because the light cycle tells it to, not because it's reached the end of its biological lifespan. Switch the light back to 18/6 after harvest, and the plant will slowly, weirdly, revert to vegetative growth.
This is re-vegging. It's slow, it's strange-looking, and it's not for every situation — but it lets you preserve genetics without taking clones, harvest twice from one root system, and discover phenos you missed.
Monster cropping is the related technique of taking clones from a flowering plant. The clones revert to veg and develop an unusually bushy structure that's ideal for training.
Re-vegging: the second harvest
When to re-veg
- You found a special phenotype and didn't take clones in veg (the most common reason). Re-vegging is your only option to keep it
- You want a second harvest from the same root system without starting from seed
- You want to preserve genetics that you can't replace (rare seeds, discontinued strains)
When NOT to re-veg
- You have clones or seeds. Starting a new plant is faster and produces healthier growth. Re-vegging takes 4–8 weeks before the plant looks normal again
- Autoflowers. Autoflowers can't re-veg — they flower based on age, not light cycle. Once they're done, they're done
- Stressed or unhealthy plants. Re-vegging requires the plant to have enough energy reserves to restart growth. A plant that barely survived flower won't survive re-veg
How to re-veg
Step 1: Harvest selectively
Don't harvest the entire plant. Leave the bottom 1/3 with small buds and fan leaves intact. These remaining leaves provide the photosynthetic capacity the plant needs to restart vegetative growth.
Removing the top 2/3 of buds is your harvest. The bottom 1/3 is the plant's recovery reserve.
Step 2: Switch the light cycle
Immediately move the plant back to 18/6 (or 20/4). The extended light period triggers the hormonal shift from flowering back to vegetative growth.