Hydroponics Blog
Calcium Deficiency in Hydroponics: Symptoms, Causes, and Fixes
Quick Answer
Calcium deficiency in hydroponics shows as brown or dead leaf tips (tip burn), blossom end rot in tomatoes, and distorted new growth. Calcium moves slowly in plants — symptoms appear on new tissue first. Fix by checking pH (5.5–6.5), confirming calcium is in your nutrient solution, and increasing airflow to improve calcium uptake through transpiration.
Symptoms by Crop
| Crop | Calcium Deficiency Symptoms |
|---|---|
| Lettuce | Brown leaf margins (tip burn), especially inner leaves |
| Tomato | Blossom end rot (dark sunken bottom of fruit) |
| Pepper | Blossom end rot, distorted young leaves |
| Strawberry | Brown leaf tips, poor fruit quality |
| All crops | Stunted new growth, curled young leaves, dark brown edges |
Why Calcium Deficiency Happens in Hydroponics
- pH too high or too low — calcium availability drops outside 5.5–6.5.
- Calcium not in nutrient solution — some budget or incomplete formulas omit calcium.
- Low transpiration — calcium moves through the plant via water flow. High humidity, low airflow, or low light reduces transpiration and stops calcium from reaching new growth.
- Excess potassium or magnesium — these compete with calcium for uptake.
- Sodium interference — high sodium in UAE tap water can block calcium. RO water eliminates this.
How to Fix It
- Check and correct pH to 5.8–6.2.
- Confirm your nutrient solution contains calcium. Use a complete two-part or three-part formula that includes calcium nitrate.
- Improve airflow around plants — a fan running 24/7 increases transpiration and calcium movement.
- Reduce humidity if above 80% — high humidity stops transpiration.
- If deficiency is severe: foliar spray with 0.15% calcium nitrate solution on leaves (not fruit) in the evening.
⚠️ Note: Calcium nitrate is the most common calcium source in hydroponics. Handle with care — keep away from other concentrated fertilisers. Do not mix calcium nitrate concentrate directly with phosphate or sulfate concentrates.