Leaves Turning Yellow
Yellow leaves can be caused by several factors;
- Incorrect nutrient solution temperature (keep solution between 18 -22°C). Use a water thermometer to measure nutrient temperature solution and use a water chiller if required.
- Low oxygen levels due to lack of aeration in the nutrient solution. Aerate the nutrient solution using air stones or pumps.
- Over-feeding (high EC). Always check the EC of your nutrient solution.
- The onset of root disease. Treat with a fungicide such as Fungarid.
- The pH is too high. Check the pH of your nutrient solution and adjust it if necessary.
- Salt build-up. Treat with a product such as BAC Flush or House & Garden Drip Clean. Flush your system every 7-10 days. If using BAC Flush or H&G Drip Clean, flush every 2-4 weeks. Always flush with pH adjusted water @ 20-23 degrees C°.
- Incorrect room temperature. Measure the room temperature and ensure it remains within the optimal zone (day temp 26 - 28°c and night temp 20 - 23°c).
All of these factors can prevent the plant from taking up nutrients in the correct quantities and balance.
Leaves Yellowing and Dying
If leaves are turning yellow from the bottom of the plant upwards – particularly in early flower, this is usually caused by root disease. Root disease is usually caused by oxygen starvation. Check the root system of the plant. If the roots are brown, it is likely caused by pythium, phytophthora, or oxygen starvation. A holistic treatment approach is required in these circumstances.
- Oxygenate your nutrient solution with an air pump, air stones or a product such as Oxy Plus
- Ensure the temperature of the nutrient solution is between 20-23°c
- Reduce the strength of your nutrient solution to ½ the usual concentration and add a fungicide such as Fungarid for 1 week. Follow-up with preventative treatments containing beneficial bacteria such as BAC Daily.
Plants Yellowing and Looking Generally Unwell
Check your light timers. Incorrect light cycles can create a lot of problems for plants. If your light timers are OK, check the root systems of the plants to determine if the roots are brown.
Brown roots are an indicator of disease, likely pythium or phytophthora. Use a product such as Fungarid to treat root diseases.
Another frequent cause is over watering. Healthy roots should clearly be white. Products that promote healthy roots include RYZO and BAC Daily.