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Ask Dr. Hort: Moisture caused dollar week; herbicide will kill it

Moisture caused dollar weed; herbicide will kill it

Q: We have an abundance of dollar weed. I am being told that the only way to get rid of it is Azatrene. After reading about the harm it can do, my husband used roundup but the weed has survived. Any suggestions? There is too much for hand digging! Linda Baker

A: There are other choices of herbicides, but what created the problem? Dollar weed gets a strong hold in moist situations, in fact, it is an aquatic plant. Once it gets started it no longer needs a moist environment to live and survive, so check your irrigation system for leaks, broken pipe or sprinklers and improper run times on the clock. Herbicides that contain imazaquin such as Image do a great job of eliminating dollar weed and nutsedge in turf or in plant beds. In a period of 3-4 weeks, your dollar weed will turn into change, then no currency at all. So don't be impatient, follow the label directions and easy on the water.

Magnolia not old enough to bloom

Q: I have a magnolia tree that is about 5 feet tall, and it gets direct sun. We give it Ortho and it still has not bloomed. Is there anything I am doing wrong?

I also read your article about leggy plants. I have a big leggy plant that has big pink blooms and once it blooms it just keeps blooming. Your article said the leggy ones should be trimmed back to about a foot tall. I sure would hate to do that to ours as it is about 4 feet tall. The only time I have seen one is at Busch Gardens. We actually have two. One is in shade and just keeps getting bigger and the one in morning sun is the oldest but it has such beautiful blooms. The one in the shade blooms also but the leaves are darker as are the flowers. Am I still supposed to trim them that much? They just started blooming now and just keep blooming. Nancy Ballard

A: Your magnolia, Magnolia grandiflora, at 5 feet isn't old enough to bloom just yet. Southern magnolia is a slow grower and must be kept moist and well fertilized to coax it along. Make a soil saucer, 4 feet in diameter, 6 inches high and fill with water every other day through the dry season (March to mid June), then twice per week if it doesn't rain. Use a quality 6-0-6, 10-0-10 with secondary nutrients such as magnesium, zinc, manganese, and 50 percent slow release nitrogen. Apply in February, May and October.

Now for the pentas. Herbaceous perennials (plants with green stems and live year to year) such as pentas could use a hair cut annually, early spring, or the growth is all at the top and bare beneath. By cutting them back, they branch and make a fuller, stockier plant with more leaves and more flowers, if 1 foot seems too drastic, try 2 feet. Pentas bloom on new growth, so after they are cut back, the growth returns as do the flowers. After pruning is a good time to hit them with a dose of fertilizer (the same 6-0-6 or 10-0-10) and be sure to water it in.

Need help? Dr. Hort (Greg Charles) answers questions about garden problems. E-mail him at or mail questions to HomeLink, Features Department, Tampa Bay Times, P.O. Box 1121, St. Petersburg, FL 33731. Describe problem in full, and include your name, city of residence and contact information. If possible, include a good-quality photo. Fuzzy ones won't do. Photos cannot be returned.

Ask Dr. Hort: Moisture caused dollar week; herbicide will kill it 06/02/12 [Last modified: Saturday, June 2, 2012 4:31am]
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