Question From: Boston, Massachusetts, United States
Q: The potted geraniums on my terrace in Boston have new- growth leaves coming in light green with normal dark green edges. I checked the plants for aphids and whiteflies and find none.. Overall the plants still look healthy and robust and have some buds. They were teeming with flowers that when faded I actively deadheaded and then fertilized with miracle grow. Earlier in the season they showed some slight mildew so I have been spraying them every 10 days with Serenade Disease Control which I learned of last year when I saw mildew on that crop of geraniums. I have been growing geraniums on my terrace each summer for the last 6 years and have never seen the new growth light green. Yearly I pot in fresh soil that has some nutrient and over watering protection. I would appreciate any information on this condition. I have a small terrace and potted geraniums are my only crop. Thank you very much.
Two things come to mind. One is the soil is too wet. Wetting agents in potting soil pose a double edge sword. This year our weather has been cool and wet and the potting soil remains wet. Geraniums like to have their soil dry out a bit between watering. Second, Miracle Gro is high in salts and can cause burning when it builds up. I prefer to use a potting soil that is free of wetting agents and fertilizers. Sadly it is hard to find. Try a hydroponic store or a garden center that also grows plants. Too much fertilizer also can cause yellowing. I prefer using a fish and kelp fertilizer such as Neptune's Harvest. It too can be purchased at a hydro store or on Amazon. I do not change my potting soil out every year unless the plants have been diseased. I mix it with a good quality compost at a rate of 2 parts potting soil and one part compost. Hope this is helpful. Best Nancy
Q: Thank you for your prompt response; it was very helpful. I have cut back on watering and will eliminate any further fertilizing. My plants seem to still be thriving, but I wonder if I should cut off the discolored leaves to help speed the recovery.
You can remove leaves, but it won't speed the recovery. Best Nancy