Plant problems · Nutrients · Any stage · Act today
pH lockout
What you see
- Several deficiencies at once: yellowing, spots and burnt edges together
- Feeding more makes it worse, not better
- Growth stalls although the plant gets food
Why it happens
Each nutrient is taken up in a pH window. When the root zone pH drifts out of range (often from unadjusted water or salt build up), nutrients are in the pot but the plant cannot use them.
What to do
- Measure the pH of what you water and of the runoff
- Flush with pH adjusted water (soil 6.5, coco and hydro 5.8) until runoff is in range
- Restart feeding at half strength and adjust the pH every time
Next time
- Adjust pH on every watering
- Calibrate the pH meter once a month
Easy to confuse with
- Magnesium deficiency: Yellowing between the veins of older and middle leaves while the veins stay green
- Nutrient burn: Leaf tips turn yellow, then brown and crispy, a few millimetres in
- Overwatering: The whole plant droops with leaves that feel firm and swollen, not limp
Not sure?
Take a photo of the whole plant, plus a close up of the worst leaf and ask the Grow Doctor, or send it to the grow companion on Telegram.