Geraniums are one of the most common flowers in the garden and provide beautiful color all summer long. Unfortunately, they aren’t immune to disease, insect infestation or bacteria, which can all cause their leaves to yellow and fall off. You can prevent this from happening to your geraniums and have beautiful flowers all summer long.
Stick your finger into the soil to check the ground or container for wetness. If the soil is damp to wet, let the plant dry out for a few days. Many times, geranium leaves turn yellow as a result of overwatering.
Thrust your fingr into the soil once again to check the soil moisture after two or three days have passed. If you’ve let the soil dry out completely but still have problems with geranium leaves turning yellow, your plant may have rust, bacterial blight, bacterial wilt or an insect infestation.
Look closely at the leaves of the flower, and note if there are any brown spots. This could be a result of bacterial blight or wilt that can spread from plant to plant when drops splash during watering. Using a soaker hose or watering can will help keep plants watered but avoid splashing of bacteria onto other geraniums.
Pick off all yellow leaves and apply a copper fungicide to help control bacteria.
Lift the geranium leaves to look for aphids or white flies. Use an insecticidal spray to get rid of them. If your geranium leaves are still turning yellow, this may be the result of subterranean termites where they burrow through stems causing the leaves to yellow. Pull out and discard any termite-infested geraniums and treat for termites.
If all of your geraniums have yellow leaves and you bought them from one home center or nursery, report it to the store as their whole shipment may have bacteria or fungus.
If you’ve found termites in geraniums planted around the foundation of your home, check the foundation for termite tunnels. If you find them, have your house treated for termites.