How do I get rid of caterpillars on my crown of thorns plant? I was told that Neem oil is not to be used and soapy water will only keep caterpillars from eating leaves.
Bt works well on caterpillars. Here is more info:
I have several other plants and they don't seem to be affected.
Black sooty mold is a fungi that latches on to the sweet, sticky honeydew secreted by many insects like aphids and scale. When the insects suck the sap, they excrete a thick gooey sugary substance called honeydew. Determine which insect is causing the problem so you can apply appropriate counter measures. Your local plant nursery can help identify them if you put them in a sealed, transparent plastic bag. If you find aphids or scale, treat your plant with Neem oil. Spray all parts of the plant extremely well but consider not spraying the flowers, which attract pollinator insects (the "good" guys). Follow the directions on the product's label.
I didn't find any publication that said to beware of massive roots, only that you needed space for a 6 ft. tall by 3 ft. wide plant. It is a slow grower so even that will take a while (most publications said 3 ft. by 3 ft. was the norm). I think you can plant it in the ground and be fine as long as you allow the 3 foot clearance.
Hi Mary Dyer gave an account on how to prune. I have one in a 20 inch pot that is over 15 years old. In the fall, I took a hedge trimmer and just cut off every limb that was over the edge of the pot. It looks horrid. I must have gone too far. Wondering if I can do something to revive the plant. Would hate to lose it. Its in the shade indoors in our plant room now.
They need four hours of sun a day, so I would move it where it can get more light. The article you referenced said crown of thorns was a forgiving plant, so hopefully it will look better in time. Follow its care instructions below.
I have had it about 6 years. I have repotted and pruned once. It sits at a window that gets the morning sun.
Usually a plant not flowering isn't getting enough light. Try moving it to a south or west facing window. You also can move these plants outdoors in the summer if you would like. Just be sure to bring it back in before the temperatures drop in the fall.
full sun 110 to 114 degrees
Tucson is in USDA hardiness plant zone 9, so you are on the edge of its hardiness for outdoors (10 and higher). It can take temperatures and heat above 90 degrees F, so you can make a judgement call here. Zone 9 still gets some below freezing temperatures and crown of thorns cannot tolerate frost. If it's in a container you can always bring it indoors for the winter. Here is more: