leaves - Knowledgebase Question

Mission, Te
Question by yameidaalani
April 8, 2010
I have grandiflora roses that its leaves are drying out and pedals have like black lining on top part. Whats the problem? im a beginner and a rose bloomed and i loved it then dryed out and no more roses. how do i keep them healthy? what do i do after fully bloomed?i live in south texas had them on full sun but noticed the rose was drying out moved to indirect sunlight and still not doing good.

Answer from NGA
April 8, 2010


The black coating the the tops of the leaves is probably sooty mold. Insects such as aphids, scales and mealybugs suck the plant juices and excrete a liquid called honeydew. The sugar content of this excrement is just high enough to encourage fungal growth. That's what you're seeing on the leaves of your rose bushes. You'll need to control the insects to keep the leaves from becoming black. Roses need all day sunshine or at least 8 hours of sun each day in order to bloom. If you keep your rose bushes well watered they should be able to take the Texas sunshine. When a rose begins to fade or lose its petals you'll need to prune it off the plant. Cut the stem down to a 5-leaflet leaf and a new flowering stem will develop. Find a garden spot with about 8 hours of sunshine each day. Amend the soil with compost or other organic matter and plant your rose. Build a watering basin beneath the rosebush and fill the basin with water, allow it to drain and then fill it a second time. This will concentrate the moisture over the root mass and allow it to trickle down and wet the entire root mass. Once a week should do it in the spring and fall; twice a week during the summer months. You can feed your rose with specialized Rose Food fertilizer and discourage insect pests with a neem oil based product such as Rose Defense. Hope your roses perk up soon!

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