Why Plant Leaves Turn Yellow - And How to Fix Them
From the carefully tended garden to the prized potted plants, yellowing leaves is a sure way to scare hobbyist growers. Known as chlorosis, the yellowing of leaves is often caused by improper watering, soil pH, a nutrient deficiency or root damage, along with pests and aging.
What is Chlorosis?
Chlorosis occurs in a plant when the chlorophyll is damaged or disrupted, which is the pigment responsible for photosynthesis and is what gives you that distinctive green colour. You should make sure to distiguish chlorosis (yellow leaves) from necrosis (brown/dead leaf tissue) as both can often appear together and tends to confuse a lot of growers.
Common Reasons For Chlorosis
Improper Watering Technique
The leading reason being chlorosis is either too much or too little water being absorbed by the plant. You should check that you have installed proper drainage and are watering reasonably, ideally until the water comes out the bottom of the pot (ensuring deep root hydration), but not more. You should also remember to empty out the saucer after around 15 minutes so your plant isn't sat in standing water.
Imbalanced Soil pH
Another primary reason that leads to chlorosis in plants is imbalanced soil pH, especially in hydroponic systems. Most plants in hydro thrive at around 5.5-6.5, while most plants in soil tend to like 6.0-7.0, and you can use pH probes and pH test kits to measure your runoff pH, as well as using pH up and pH down additives to adjust accordingly.
Nutrient Deficiency
Conclusion
The yellowing of leaves in plants (chlorosis) is often caused by improper watering or nutrient deficiency- and can often be cured quickly, however if it is caused by viral infections, pests or root damage, the plant can often not be saved. Chlorosis is important to treat as it slows down photosynthesis across the entire plant by stopping it entirely in affected areas, which can stunt overall growth.
FAQ:
Can chlorotic leaves be turned green again?
Only if the chlorosis is recent, and is treated quickly. Leaf yellowing caused by aging, root rot or pests cannot be cured.
What's the difference between chlorosis and a nitrogen deficiency?
Chlorosis is the yellowing of leaves in a plant, whereas a nitrogen deficiency is just one specific cause of chlorosis.
How quickly does chlorosis spread?
It depends entirely on the cause. Yellowing caused by a nutrient deficiency spreads slowly, and only continues as long as the plant is deprived of the correct nutrients, however viral infections, waterlogging or root damage/root rot spreads much faster, and can be significantly harder to cure.
Can too much water cause yellow leaves?
Yes, absolutely. Overwatering is one of the main causes of chlorosis, and can cause the leaves to go yellow, soft and limp and will halt photosynthesis in affected areas, leading to stunted growth in the entire plant.
