HST (High-Stress Training)
Definition: High-stress training (HST) is any cannabis training method that deliberately damages plant tissue, such as cutting, crushing, or snapping stems, to change the plant's shape and growth pattern. Common HST techniques include topping, FIMming, supercropping, and monster cropping. Plants need several days of recovery after each session.
How HST (High-Stress Training) works
The idea behind HST is controlled injury. When a stem is cut or crushed, the plant reroutes growth hormones and builds thicker tissue around the wound. Growers use that response to break up a single dominant cola, keep plants short, or flatten an uneven canopy.
Common HST methods
| Technique | What you do | Typical timing |
|---|---|---|
| Topping | Cut the main tip above a node | Veg, 4 to 6 nodes |
| FIMming | Pinch off most of the newest growth | Veg, 3 to 5 nodes |
| Supercropping | Crush and bend a soft stem | Late veg to early flower |
| Monster cropping | Root cuttings taken from a flowering plant | Weeks 2 to 3 of flower |
Rules of thumb
- Only stress plants that are healthy, well-rooted, and growing fast.
- Allow 5 to 7 days between sessions, and never stack several techniques on the same day.
- Do the heavy work in veg. Damage late in flower diverts energy from buds and, in some genetics, can raise the chance of a hermaphrodite.
- Go light on autoflowers, which have a fixed timeline and little room to recover.
HST is not required to grow good cannabis. It shines when you have limited height, a single plant to fill a large footprint, or a tall sativa-leaning strain that would otherwise climb into the light.