Topping Practice for Cannabis

Topping removes the apical shoot during vegetative growth to interrupt apical dominance. This hormonal shift redistributes growth to lateral buds so plants branch wider and present more productive sites under uniform light. In practice this supports higher usable flowers per square meter and steadier quality for medical cannabis wholesale in Thailand. The physiology is well studied in horticulture: removing the shoot tip reduces auxin influence and allows cytokinin-driven axillary buds to extend.

Confirm the plant is ready

Work only in vegetative growth on vigorous plants. A common window is once the main stem has 4–6 complete nodes and roots are established. Most plants recover within 3–7 days if conditions are stable.

Prepare tools and the bench

Sanitize cutting tools before and after each session to avoid moving pathogens between plants. Extension guidance supports wiping or dipping pruners in isopropyl or ethanol at 70 percent or higher, used straight from the bottle. Staff should work clean with gloves, masks or hair covers, and a tidy bench, then bag green waste and clear the aisle. Clean handling reduces disease pressure and aligns with documentation expectations under GACP.

Pick the cut point

Count nodes from the base. Choose a healthy node stack that will carry the new tops evenly under your lights. Make a clean cut just above the chosen node so the two axillary buds below receive energy and become new leaders. Avoid cutting into the node.

Aftercare in the first 72 hours

Return plants to steady VPD, light, and irrigation. Do not stack other high-stress tasks on the same day. Inspect 24–48 hours later. If one side lags, use gentle low-stress training to balance height for uniform PPFD. Recovery typically completes within one week for vigorous plants.

When to top again and when to flip

If you plan a second topping, wait until each new leader has produced several nodes and the plant has fully resumed growth. Many programs allow 1–2 toppings before flowers. Allow a short recovery window before switching to 12/12.

• Keep the canopy level. Topping is most effective when combined with even light and airflow.
• Do not top in flowers. Hormonal priorities have shifted and recovery can reduce yield.
• Be cautious with auto flowers. Their short veg period limits recovery. Many growers avoid topping autos or only top very early on vigorous plants.
• Consider selective cleanup below the first node after topping if those sites never produce strong branches in your cultivar. This concentrates growth on upper nodes.

Training is effective only with stable room conditions. Keep airflow through the canopy and manage humidity, since persistent high humidity supports fungal problems in flowers. Facilities that pair pruning discipline with RH control report fewer mold events and more predictable drying. Monitor lights-off periods when RH spikes are common.

What does topping change inside the plant?

It reduces apical dominance and releases axillary buds, which then extend and become new tops.

When should I avoid topping?

Avoid topping in flowers and avoid topping weak or stressed plants. Most programs top once plants are vigorous at mid-veg.