Grow Guide . troubleshooting . G-05
why they stall,
how to fix it.
Clones not rooting is almost always one of four problems. Temperature, humidity, contamination, or a weak cutting. Diagnosing which one is the issue saves the batch.
Symptom: cuttings look healthy on top but no roots emerge past day 10. Diagnosis: feel the bottom of the tray. If cool to the touch, root zone is too cold. Fix: heating mat set to 75 to 78 degrees.
Symptom: leaves wilt, edges curl. Diagnosis: hygrometer reads below 60 percent. Fix: mist the inside of the dome twice a day. Aim for 70 to 80 percent in the dome.
Symptom: cut end turns brown or black, stem feels mushy. Fix: dispose of the cutting. Sanitize tools with 70 percent isopropyl. Take a fresh cut from clean stock.
Symptom: cutting limps from day one. Diagnosis: cuttings from heavily fertilized mothers resist rooting. Cuttings taken too thick or too thin do not root well. Reveg cuts take 3x longer.
Symptom: roots start to emerge then yellow and stop. Fix: replace the medium. Rockwool needs pre-soaking in pH 5.5 water. Peat plugs need pH 6.0.
Symptom: cuttings look bleached, top leaves curl down. Fix: drop to 200 PPFD or move the light farther from the tray.
Start with temperature. Feel the bottom of the tray. Then check humidity. Then look at the cut ends for rot.
Sometimes. Recut the bottom inch fresh, re-dip in rooting hormone, return to a clean plug. Success rate about 30 percent.
Genetic variation, branch position on the mother, thickness of the cut, microvariations in plug humidity.
Yes. Commercial nurseries see 5 to 10 percent failure rates. Home growers see 15 to 30 percent for first attempts.
Day 21 with no visible roots, in corrected conditions, means it is not going to root.