Plant problems · Nutrients · Any stage · Act this week

Calcium deficiency

What you see

• Small brown spots with sharp edges on new and middle leaves
• New growth is twisted or crinkled
• Leaf edges die back in irregular patches
• Common in coco, in reverse osmosis water and under strong LED lights

Why it happens

Calcium does not move inside the plant, so new growth shows it first. Pure or soft water, coco that binds calcium, a pH below 6.2 or poor transpiration in high humidity cause it.

What to do

1. Add a calcium and magnesium supplement to every feed, especially with coco or RO water
2. Keep soil pH between 6.2 and 7.0
3. Improve air movement so the plant transpires and carries calcium up

Next time

• Buffer coco before use
• Use cal mag from the start with soft water

Easy to confuse with

• Magnesium deficiency: Yellowing between the veins of older and middle leaves while the veins stay green
• Light burn and light bleaching: The top leaves closest to the light turn yellow or white while their veins stay green
• Septoria leaf spot: Round yellow spots on lower leaves that turn brown with a yellow halo

Not sure?

Take a photo of new leaves near the top, close up, with the spots in focus and ask the Grow Doctor, or send it to the grow companion on Telegram.

More nutrients problems

• Nitrogen deficiency
• Too much nitrogen (the claw)
• Phosphorus deficiency
• Potassium deficiency
• Magnesium deficiency
• Iron deficiency
• Sulfur deficiency
• Zinc deficiency
• Manganese deficiency
• Boron deficiency
• Nutrient burn
• pH lockout