# Tan or tea-stained roots that are still firm: likely causes and fixes

> Tan or tea-stained roots that are still firm on cannabis is most often Harmless root staining (nutrients, tannins, additives) or Ammonium toxicity (too much NH4 in the feed). How to tell them apart, the fix for each and what recovery looks like.

Also called: roots turning tan, stained roots, orange roots, roots not white but firm.

Run the checker with this sign: https://genetixbay.com/knowledge/diagnose/?at=roots&s=roots-stained-firm

## Likely causes, most likely first

### Harmless root staining (nutrients, tannins, additives) (Likely)

- Kind: Root zone; urgency: Low urgency
- Fix: Nothing to fix if roots are firm, odourless and still growing white tips. Organic additives, humic products and some nutrient colours stain roots tan.
- Recovery: New tips keep appearing white; plant grows normally.
- Confirm: Look at the roots: Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
- Confirm: Smell test of roots, medium and reservoir: Smell the roots, the bottom of the root ball, the drain water or the reservoir up close. Healthy roots smell earthy or of nothing. A sour, rotten, swampy or sewage smell means anaerobic conditions and rot. In hydro, a slimy feel on the reservoir walls or tubing adds to the case.
- Article: [Brown roots in hydroponics (DWC, RDWC, NFT): a differential](https://genetixbay.com/knowledge/diagnosis/root-browning-hydro.md)

### Ammonium toxicity (too much NH4 in the feed) (Less likely)

- Kind: Too much of something; urgency: Deal with it this week
- Fix: Keep ammonium at or below about 10-30% of total N (cannabis trials showed toxicity and lost yield above ~30%); switch to a mostly nitrate feed and correct root-zone pH.
- Recovery: pH stops falling and new leaves lose the dark claw within a week.
- Confirm: Measure input pH and root-zone (runoff or reservoir) pH: Calibrate the meter with fresh pH 7 and pH 4 buffers, then measure the mixed feed and the runoff (containers) or reservoir (hydro). Soil and living soil should sit at 6.0-7.0, coco, rockwool and peat mixes at 5.5-6.5, hydro at 5.5-6.2. Track 3+ readings; one reading is not a trend.
- Confirm: Look at the roots: Hydro: lift the net pot and look at the root mass in good white light. Containers: tip the plant out with a hand over the medium and look at the edges and bottom of the root ball. Healthy roots are white to cream with fine fuzzy tips. Brown roots whose outer layer slides off between the fingers leave a bare thread: rot. Firm, evenly tan roots with white tips in coloured solution are staining.
- Article: [Nitrogen (N) in cannabis: nitrate vs ammonium, deficiency, toxicity and targets](https://genetixbay.com/knowledge/nutrients/nitrogen.md)

## Note

Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.