A Note on Temperature
- It's crucial to understand the difference between ambient air temperature and water temperature. The temperatures on our Plant Guide cards refer to the ideal AIR temperature.
- High ambient heat will raise your water temperature. Warm water holds less dissolved oxygen, which is the leading cause of root rot and crop failure.
- The ideal water temperature for most hydroponic plants is between 18-22°C (65-72°F). Managing this is the key to success in hot climates.
Root Rot & Heat Stress
The #1 killer of hydroponic plants, especially in warm climates. Caused by poor oxygenation from high water temperatures or pathogens. Roots will appear slimy, brown, and have a foul smell. Above ground, the plant will wilt and look droopy, as if it's underwatered.
Remedy
- Keep water temperature between 18-22°C (65-72°F). This is critical.
- Increase aeration in your reservoir using a larger air pump or more air stones.
- Use a water chiller or add frozen water bottles to the reservoir in hot weather.
- Paint reservoirs white or use insulated ones to reflect heat.
- Add beneficial bacteria (like Hydroguard) to outcompete harmful pathogens.
- Gently clean the affected roots and trim away any dead, brown material before returning to a sterile system.
pH Imbalance
Incorrect pH is one of the most common issues, locking out nutrients even if they are present in the solution. Look for stunted growth, yellowing leaves, or brown spots.
Remedy
- Test your pH daily using a calibrated meter or test strips.
- If pH is too high (alkaline), add pH Down (phosphoric acid).
- If pH is too low (acidic), add pH Up (potassium hydroxide).
- Add small amounts, mix well, and re-test after 15-30 minutes before adding more.
Nutrient Burn (High EC)
Caused by a nutrient solution that is too concentrated. Symptoms include dark green leaves, weak stems, and burnt, crispy leaf tips that curl downwards.
Remedy
- Check your EC (Electrical Conductivity) or TDS meter reading.
- Dilute your nutrient reservoir with fresh, pH-balanced water.
- Reduce the amount of nutrients in your next mix.
- Flush the system with plain, pH-balanced water for a day if the problem is severe.
Nitrogen Deficiency
Nitrogen is vital for leaf growth. The most common sign is a general yellowing (chlorosis) of the older, lower leaves. The yellowing will then move up the plant. Growth will be stunted.
Remedy
- Ensure your pH is in the correct range for Nitrogen uptake (usually 5.5-6.5).
- Use a complete hydroponic nutrient formula with a balanced N-P-K ratio.
- Consider a Cal-Mag supplement, as many also contain Nitrogen.
- For a quick fix, a diluted foliar spray with a nitrogen-rich solution can be used, but address the root cause.
Calcium Deficiency
Calcium is crucial for cell wall development. Deficiency often appears in new growth, causing stunted, deformed, or dead leaves at the growing tips. In fruiting plants, it causes blossom-end rot (dark, mushy spots on the bottom of fruits).
Remedy
- Ensure pH is not too low, as this can lock out Calcium.
- Use a comprehensive nutrient solution that includes Calcium.
- Supplement with Calcium Nitrate or a dedicated Cal-Mag product.
- Maintain good air circulation to promote transpiration, which helps transport Calcium through the plant.
Pest Infestation (Aphids/Spider Mites)
Small pests that suck sap from your plants. Look for tiny dots (the pests themselves), webbing (spider mites), yellow stippling on leaves, or a sticky 'honeydew' substance (aphids).
Remedy
- Introduce beneficial insects like ladybugs or predatory mites as a preventative measure.
- For minor infestations, wipe pests off with a damp cloth or spray with a strong jet of water.
- Use insecticidal soap or neem oil sprays, ensuring complete coverage, especially under leaves.
- Isolate new plants before introducing them to your main grow area to prevent spread.