Why they appear and how to take care of them.
Yellowing leaves are a common sight on plants. They can be caused by a multitude of different problems which affect the production of chlorophyll, such as a pH imbalance in soil, hard tap water, toxic gas such as that from a stove, weed-killing chemicals, plant pests, an unhealthy amount of sunlight or water (water stress), or simply aging.
Some things to look for, outside of obvious things… like a broken limb:
Where you are in the growing season – if the leaves are growing old and turn yellow, this is usually not a sign of a plant problem. This only means the leaves are done growing and new leaves will grow in soon.
The pH level of your soil – if the pH level is more than 7.0, the plant most likely cannot take in iron, which is necessary in the process of photosynthesis. If the pH level is too low, the plant may not be able to take in magnesium. A high lime level in your water can cause soil to become too high in pH. Look for potting soils with proper pH for your plant, as well as soil-balancing amendments.
The placement of your plant – if the plant receives too much or too little sunlight, the process of photosynthesis will malfunction and cause a loss in the green color of the leaves. Or if you have your plant near a stove with a gas range, this could be dangerous to the plant.
Soil moisture – most gardeners recommend that when you water a plant, the soil should feel cool and moist to the touch without dampening your finger. Over-watering or under-watering can damage the plant.
Nutrients – Nutrient deficiency can cause yellowing. However, too much fertilizer can also cause leaf yellowing from salt damage. If you have been fertilizing heavily, cut back and see if that helps. If you haven’t been fertilizing much at all, try fertilizing a bit more. Using the wrong fertilizer can also cause problems.
Pests – They’re reasonably easy to spot and and there are many pest-control methods available to get rid of them.