Volcano mulching likely to seriously stress trees


Published: Friday, January 16, 2009 at 6:01 a.m.
Last Modified: Thursday, January 15, 2009 at 12:34 p.m.

Volcano mulching makes Wendy blow her top and lucky bamboo gets a new home

Q: I have noticed in parking lots and in some medians that the landscapers really mound up the mulch tall around the tree trunks. Why do they do this, and what is the benefit?

A: Sometimes too much of a good thing can be wonderful, but not in the case of mulch. Proper mulching is one of the best things you can do in the landscape to make it Florida friendly. University of Florida IFAS recommends using a 2- to 3-inch layer of mulch underneath established trees. The practice you are seeing is called "volcano" mulching and it is not healthy for the tree or shrubs.

Mulch should be spread beneath the drip line of the tree and beyond if desired. Take special care not to let the mulch touch the trunk or stems of the trees. If the mulch is mounded up like a volcano right on the trunk, fungal rot can move into the trunk and the air flow to the roots will be cut down. This can actually suffocate the roots if the mulching material is thick and deep. Also, small feeder roots can move up into the mound of mulch instead of down into the soil. Ultimately, when the mulch breaks down these roots will dry out and lead to the demise of the tree.

Mulching properly at 2- to 3-inches deep under the canopy of mature trees will reduce the need for mowing, suppress weed growth, reduce soil temperatures and help to keep the soil moist. Volcano mulching will only end up hurting the trees.

New research from UF tree expert Ed Gilman shows that newly planted trees have better success when mulch is kept off the actual root ball. Gilman reports this mulch can intercept irrigation and light rains that could benefit the tree by reaching the roots. He recommends using the mulch at the 2- to 3-inch depth beyond the root ball out to the drip line but keeping the root ball clear or just lightly mulched until the tree is established and growing well. For more information about mulching, visit the www.solutionsforyourlife.com and read the new publication titled "Frequently asked questions about Florida friendly landscaping."

Q: I have two so-called lucky bamboo plants growing in water indoors. One is reaching for the ceiling and the other is growing slower. I want to repot both of them in another container with pebbles. What is the root system? Do I just take them from one pot and put both in another?

A: Since you are calling it "so-called" lucky bamboo, I am guessing that you already know that they are not a true bamboo, but I do hope that they have been lucky for you. This very tough indoor plant is Dracaena sanderiana, and it is often sold as a feng shui accessory. It is closely related to the "corn plant" that also is a popular houseplant.

Lucky Bamboo thrives in low-light settings and can grow pretty well without soil. You often see it in vases with only water or decorative containers with pebbles. It is a great plant for offices or other low-light settings. To repot or change the container, simply move the two plants to a new pot without drainage holes. When you remove each from its current pot, the roots will hold on to some of the pebbles; this is fine. Place each in the new container and add more pebbles of a similar size and situate the stems so they are stable. It is as simple as that.

The stems will sprout new roots if you increase the water level, so if you would like to put the two in a deeper pot you can do that. If the tall stemmed plant is very lanky, you could trim the stem down to about 12 inches and place the clipped stem in the container, new roots will sprout from the stem and the plants will look more even.

Chlorinated water can cause problems for lucky bamboo, so you may want to consider using filtered or bottled water. Change the water on a regular basis so it doesn't become stagnant, and occasionally add a diluted solution of a liquid fertilizer to keep the plants green and growing.

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