Short answer
No. Unrooted cannabis clones live on their own reserves, so plain water or a very weak solution (EC up to about 0.4 mS/cm, 200 ppm500) is enough. Start feeding at EC 0.4–0.8 mS/cm once roots appear. Grower practice.
Why
A cutting has no roots to take up much feed. Its job is to make roots from the sugars and nutrients already in its stem and leaves.
Research cuttings root on almost nothing. In one cannabis substrate trial, cuttings were kept on water at an EC of just 0.20 mS/cm and still rooted within 9 days in the best medium [1].
The leaves are the cutting's pantry. Cuttings with three leaves made better roots than those with two [2], which is why stripping leaves hurts more than skipping feed.
Salt at a fresh wound is a stressor. A strong solution around the stem base draws water out rather than in.
Feeding has its moment. Extension seedling guidance waits until true leaves form before adding fertiliser [3]; for clones the equivalent is visible roots.
The numbers
| Stage | EC (mS/cm) | ppm500 | ppm700 |
|---|---|---|---|
| Unrooted cutting | 0–0.4 | 0–200 | 0–280 |
| Rooted clone / seedling, 2–3 true-leaf sets | 0.4–0.8 | 200–400 | 280–560 |
| Plug pH, rockwool | 5.5–6.0 | ||
| Plug pH, coco or peat | 5.8–6.2 |
What to do
- Soak plugs in pH-adjusted plain water, or EC ≤ 0.4.
- Keep plugs moist, not dripping.
- Mist with plain water only, if at all.
- When roots show, give a quarter-strength feed (EC ~0.4).
- Step up to half strength (EC ~0.8) after transplant as new growth starts.
Common mistakes
- Soaking plugs in full-strength veg feed.
- Foliar spraying nutrients under a sealed dome.
- Treating normal lower-leaf yellowing on day 7–10 as a deficiency.
- Never feeding rooted clones sitting in inert plugs.
Related
- Full article: Clone-only cuts and how to preserve them
- Why are my seedling's leaves yellow? · Best medium for rooting clones
- Terms: EC · ppm500
