Yellow Leaves On Roses
Gardening Question From Chris:
I have been following your Rose Pro program from your Southern California gardening book. The roses in my back yard and the front yard roses in pots are doing well. However, the roses in my front yard which are planted directly in the ground have yellowing leaves. The leaf itself turns yellow first, and then the veins turn yellow. I have also noticed this on my camellias which are also planted in the ground. Is there something I should be doing beyond your Rose Pro program? Thank you.
Answer from Pat:
Yellow leaves on roses can be caused by a variety of factors. Whenever a plant has yellow leaves the first thing one thinks of is lack of nitrogen, but if you are following the Rose Pro method that is unlikely to be the problem with your roses. Secondly if a leaf turns yellow but has green veins, then one thinks of chlorosis. Chlorosis (yellow leaves with green veins) is caused by an insufficiency of iron within a plant. Camellias prefer acid soil and may suffer yellow leaves from chlorosis if they are growing in soil that is too alkaline. This can happen annually since our water is alkaline. Make sure that your camellias are being fed with acid fertilizer. As I am sure you understand, since you use my book, we don’t use the same fertilizers on camellias that we would give to roses. If you overfed camellias with phosphorus this also might cause chlorosis, since phosphorus can prevent uptake of iron. To correct this problem I suggest you apply chelated iron to the ground over the roots surrounding your camellias according to package directions.
If the yellow leaves on your roses are down low on the rose bushes, this might be caused by thick foliage higher up on the plant shading out the lower parts of the bush. This is natural and will stop when the plant has dropped off enough leaves as it grows taller. If trees in the area have put on more foliage than they once had thus causing more shade, this too can make roses suffer from yellow and dropping leaves. Extremely hot weather can also make rose leaves go yellow and fall off and so can swings of temperature from hot to cold or cold to hot, which unfortunately some areas have experienced this year. Mites can also cause yellow leaves. (Knock them off with water from the hose and use soapy sprays or other organic miticides.)
I have another idea as well: The fact that the camellias as well as the roses in your front yard this year have yellow leaves makes me wonder if the problem might be root rot of both plants due to poor drainage and heavy clay soil. If the soil in your front yard is clay or if it is waterlogged in this area I suggest treating you entire front yard with soluble gypsum according to package directions and watering it in to the ground. Do this job annually. Applying soluble gypsum to poorly drained soil according to package directions will do no harm and might do a lot of good.
