How Many Times to Top Cannabis Plants | Pop's Cannabis

Quick answer

Top a photoperiod cannabis plant once or twice. A third topping works if you plan a vegetative phase of eight weeks or more and the plant stays healthy. Autoflowers get zero toppings in most cases. If you top an autoflower, do it once, above the fourth node, before day 21 from sprout.

when to top cannabis plants for best yield

What topping does to a cannabis plant

Topping cuts the apical meristem, the main growth tip at the top of the plant. That cut removes the source of auxin that keeps lower branches suppressed. The plant responds by pushing two new shoots from the node below the cut. Repeat the process and each top splits into two more. One cut turns one cola into two. Two cuts can turn one main cola into four. Three cuts can produce eight.

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Recommended topping counts by grow type

Indoor photoperiod plants

One topping for small tents and short veg cycles. Two toppings for plants in a 4x4 or larger space with six to eight weeks of veg. Three toppings only for screen of green setups, long veg, and vigorous strains.

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Outdoor photoperiod plants

Two toppings suit most outdoor grows. A third is common in long-season climates with a veg period over ten weeks. Outdoor plants can handle a fourth topping in warm regions, but the canopy gets wide and needs support.

Autoflowering plants

Skip topping. Autoflowers run on a fixed clock and have little time to recover. If you do top one, do it once at the fourth node by day 18 to 21. Never top an autoflower after it shows pistils.

Minimum spacing between toppings

Wait for full recovery before the next cut. That means new growth of two to three nodes below the previous cut, usually five to ten days. Topping twice in the same week stalls the plant and can cost you two weeks of growth.

Signs you should stop topping

• The plant has switched to flowering.
• Growth has slowed or leaves show nutrient problems.
• The plant is under 6 inches tall or has fewer than four nodes.
• An autoflower is past day 21.
• The canopy already fills the space.

How to top a cannabis plant

1. Wait until the plant has at least five to six nodes.
2. Sterilize a pair of sharp scissors or pruning snips with isopropyl alcohol.
3. Locate the newest growth tip at the top of the main stem.
4. Cut just above the fourth or fifth node, leaving a small stub.
5. Leave the plant alone for five to seven days.
6. Check for two new shoots emerging from the node below the cut.
7. Repeat the cut on each new shoot if you want more tops.

Common mistakes

• Topping during flower, which wastes the plant's energy.
• Topping a sick or slow-growing plant.
• Topping autos late or more than once.
• Skipping sterilization and risking infection at the cut.
• Topping again before the last cut has healed.