When to Start Training Cannabis Plants: Node Counts

Short answer

Start training a photoperiod cannabis plant at 3 to 5 nodes. That is day 14 to day 21 from sprout for most indoor plants. Autoflowers need work sooner, at day 14 to day 21, and high stress methods such as topping fit a narrow window. Seedlings below 3 nodes have soft stems and little leaf area. Training at that stage slows growth and can snap the stem.

What Is LST in Cannabis Growing? Low Stress Training Guide

What a node is

A node is the point on the main stem where a leaf and a branch meet. Count from the first set of true leaves with serrated edges. The two round cotyledons and the first single blade leaves do not count. Three nodes means three sets of branches on the main stem.

what is lst in cannabis growing

Photoperiod plants

• Day 1 to 14: seedling. No training. Water and light.
• Node 3 to 5, day 14 to 21: low stress training. Bend the main stem to horizontal and tie it down.
• Node 4 to 6, day 21 to 28: topping. Cut the stem above the node with clean scissors.
• Veg week 3 to 6: supercropping on stems that no longer bend by hand.
• Flower week 1 to 2: weave branches through a SCROG net during stretch. Stop high stress work here.

Veg runs 4 to 8 weeks indoors. Recovery from topping takes 4 to 7 days. Plan the flip to 12/12 at least 7 days after the last cut.

SCROG Net Cannabis Training: The Complete Guide to an Even Canopy

Autoflower plants

Autos flower on their own clock, often 3 to 5 weeks from sprout. The window is short.

• Day 14 to 21, node 4 to 5: start LST. Tie the main stem to one side.
• Day 18 to 21: top once. That cut suits plants with 5 nodes and fast growth. Skip it on small or slow plants.
• Day 30 onward: leaf tucking and light defoliation.

Do not top an autoflower after day 25. Recovery time overlaps with the stretch and cuts yield.

Supercropping

Pinch the stem between thumb and index finger. Roll it until the inner tissue softens. Bend the branch to 90 degrees. The stem forms a knuckle and hardens in 3 to 7 days. Use this in veg week 3 to 6. Do not supercrop after flower week 3.

SCROG net

Set the net 8 to 12 inches above the pot rim. Install it when the canopy reaches 12 to 18 inches. Weave the tallest branches under the squares. Fill 70 to 80 percent of the net before the flip.

Defoliation

Remove fan leaves that block bud sites. Two windows work: flower day 21 and flower day 42. Take 20 to 30 percent of leaves at one time. More than that stalls growth.

Signs to wait

• Fewer than 3 nodes.
• Yellow lower leaves or slow growth.
• Roots not yet at the pot walls after transplant. Wait 5 to 7 days.
• Plant under 12 inches and 21 days into flower. Leaves stay.

Timing details that matter

Train at lights on. Stems are firm then and the plant heals during the light period. Room temp 70 to 80 F and relative humidity 50 to 60 percent help recovery. Skip water on the day of topping, then water the next day. Clean scissors with 70 percent isopropyl alcohol between plants.