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Ask Dr. Hort: Remove old flower stocks on kalanchoes

Give up on damaged Chinese fan palms

Q: A new problem has developed after this severe winter. I have two Chinese fan palms, pictured above, that were supposed to be hardy. As the photo shows, new growth on the smaller of the two has prematurely yellowed and appears dead at the top. Some of the lower branches are also very brown. Both plants' leaves have always gotten very brown more quickly than expected on their outer edges — they are exposed to lots of wind. These were planted more than three years ago, and receive the same fertilizer and water. Can I salvage the smaller one?

Lawrence R. Jauch, Homosassa

A: I'm afraid there is bad news on both accounts. It is extremely difficult to identify these palms as Chinese fan as they are both deficient. Chinese fan palms with that much clear trunk should have fronds 4 feet across and 8 feet in length. The smaller one has succumbed to Texas palm decline, an incurable disease. I would remove both palms and start over.

Treat flowering bushes rigorously for pests

Q: Every year my gardenia bush gets something that looks like black soot on the leaves and the camellia bush gets something that looks like cobwebs all over it. I seldom get any blooms, except a few months ago I started putting Miracle-Gro Acid Fertilizer on them and did get a few blooms on the camellia bush. They are in an atrium and face east. Thank you for any help you can give me.

Shirli Kleiber, Sun City Center

A: A favorite insect pest of gardenia is white fly, and tea scale loves camellia. Actually they are both soft scales, so we'll treat them with one product, horticultural oil. Horticultural oil works by smothering the scale, so multiple applications will be necessary and the spray will have to come in contact with the insect. Both scales are concentrated on the bottom side of the leaves so the spray needs to be directed there. Applications should be made every two weeks for a total of three applications, then monitor weekly. It is very important to cover 100 percent of the infected area, and as with all pesticides, follow label directions. Continue to fertilize every four months to increase vigor for bloom next year.

Remove old flower stalks on kalanchoes

Q: I purchased four kalanchoes about a month ago when they were in full bloom. I have never grown them before but everyone said they were great plants. I have them planted in window boxes. They continued to bloom a couple of weeks and then died off. Will they rebloom if I do nothing or should I cut off the old bloom stems? How late should they keep blooming in the fall? Can I bring in the same plants in the fall and grow them inside or should I just leave them outdoors?

Mary Remmel, Largo

A: Kalanchoes bloom best in full sun, so don't try to grow them for continuous bloom in the house. Outside they will continue to bloom if you remove old flower stalks (a process called dead-heading), provided sunlight is sufficient.

Tracking down Mexican sunflower

Q: I have been looking for a nursery or store that sells Mexican or Bolivian sunflowers with no luck. I have called numerous nurseries, gone online and tried seed catalogs. Can you tell me where I can purchase these bushes locally? I would love to replace the nine ficus trees that I lost with these showy, attractive flowering shrubs.

Harri Miller, Clearwater

A: I think the plant you are looking for, called Mexican sunflower, is Tithonia rotundifolia. It grows up to 10 feet and dies to the ground each year. Use the scientific name in your search. If you know someone with the plant, get some cuttings, stick them in the ground and they will root.

Need help?

Enter Greg "Dr. Hort" Charles, who for more than 30 years educated gardeners through the Pinellas Technical Education Centers. He answers questions about landscape and garden pests. E-mail your questions to drhort@ or to (put Dr. Hort in the subject line). Mail questions to HomeLink, Features Department, St. Petersburg Times, P.O. Box 1121, St. Petersburg, FL 33731. Describe your problem in full, and include your name, city and contact information. If possible, include a photo. We will print his advice on Saturdays in HomeLink.

Ask Dr. Hort: Remove old flower stocks on kalanchoes 06/04/10 [Last modified: Friday, June 4, 2010 4:30am]
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