Gardening: How much mulch do you need

EILEEN WARD
David Albers/Staff 
 - Local entrepreneurs Michael and Peggy Hoggatt have developed a product called EnviroHOLD as a water-based garden adhesive that locks mulch into place.

Photo by DAVID ALBERS

David Albers/Staff - Local entrepreneurs Michael and Peggy Hoggatt have developed a product called EnviroHOLD as a water-based garden adhesive that locks mulch into place.

This is the time of year when snow birds and tourists return to the island. Everyone is busy cleaning the last of the summer growth from their landscapes. Many people will begin mulching their gardens as mulching adds a uniformity to the landscape which makes it appear neat and pleasing to the eye.

If your landscape is planted and maintained properly you should need less and less mulch as the years go by. Plants should be allowed to mature so that they become one large mass in your garden beds and should always be trimmed so that the foliage shades the ground underneath. This does not allow weed seeds to germinate due to the lack of sunlight. But mulching plant beds in the landscape is a good thing to do for many reasons. Mulch cools the soil to help retains soil moisture, reduces weed growth in open areas, and decomposes to add organic matter to the soil. It will cover the sticks and leaves left behind by summers excessive growth which will decompose and generate more organic matter to help combat poor soil conditions.

Mulch should be applied evenly throughout the beds at a depth of four inches if this is the first application or two to three inches if previously mulched beds are being redressed. Always leave an inch or two of breathing space around the stems or trunks or the plants and trees. Mulch applied next to plant stems can cause rot from the constant moisture and this could result in their death.

Never mulch citrus trees. Citrus trees prefer a clean, raked soil under them out to the drip line. They have very shallow feeder roots which are susceptible to disease when constantly moist. If the tree develops foot rot it will attack the bark of the lower trunk causing it to peel and lift away. In time this will girdle the entire tree causing death. Once the disease appears it is not curable. You can try to slow the progress of the disease by cleaning the loose bark and applying a fungicide to the area.

There are many types of mulch to choose from. Chipped is cheaper than shredded mulch. The chipped mulch will wash away much quicker than shredded. Shredded will matt together and stay in place while it decomposes. You can get shredded or chipped mulches made from the wood of cypress, eucalyptus or Florimulch from the melaleuca tree. Another mulch is pine-bark. This mulch which tends to stay in place a long time and has a more rustic look. Or pine-straw, which is really pine-needles and has a soft, fluffy appearance. The various types of mulch are all different in color and smell so it is really a matter of personal preference which is the best. Since the melaleuca tree is a nuisance tree which we are trying to eradicate from our native forests, Florimulch or Enviromulch would be good choices environmentally.

Dyed or colored mulches like red, black and gold mulch, which have been very popular since coming on the market, may be hazardous to your health. Two Florida engineers, Helena Solo-Gabriele of the University of Miami and Tim Townsend of the University of Florida studied the use of lumber debris. Some dyed mulch is made from lumber debris. Dyed landscape mulch containing wood treated with CCA(chromium, copper and arsenic), or better known as pressure treated wood can raise the level of arsenic in soil above safe levels. Walt Disney World will not use treated lumber anywhere they keep animals. Cooperative Extension agents advise against using CCA treated wood in vegetable and fruit gardens or in children's play areas. While not all dyed mulch contains debris from pressure treated wood, some brands do. If you still want to use this kind of mulch, you should examine it closely looking for particle board or plywood. If the mulch contains either try buying another brand or kind. Marco is a small island and we use our ground water through reverse osmosis. You should use dyed mulch cautiously.

Florimulch or Enviromulch have been around for many years. It used to be hard to find but is becoming more popular. I have always been intrigued by this mulch as a good replacement for cypress mulch, which is the mulch most people use. Cypress trees are very slow growing and we are cutting them down at an alarming rate to mulch our gardens. Melaleuca, on the other hand, is a tree we are trying to eradicate from our native forests. This mulch also seems to repel many insects including termites. And it is not contaminated with arsenic and other chemicals found in the dyed, recycled wood mulches. It decomposes more slowly and is a no-float mulch.

Florimulch or Enviromulch are my top choices for mulching your gardens. They are an easy way to help the environment while improving your property. It costs a little more for a bag than other mulches but you should just consider that a charitable contribution to helping our native forests.

How much mulch will you need? By the bag. At a depth of two inches a 2 cu. ft. bag will cover 12 sq. ft. and a 3 cu. ft. bag will cover 16 sq. ft. At a depth of 3 inches a 2 cu. ft. bag will cover 8 sq. ft. and a 3 cu. ft. bag will cover 12 sq. ft. At a depth of four inches a 2 cu. ft. bag will cover 6 sq. ft. and a 3 cu. ft. bag will cover 8 sq. ft. in bulk; 1 cu. yd. will cover 162 sq. ft. at a depth of 2 inches – 129 sq. ft. at 3 inches or 81 sq. ft. at four inches. To figure area multiply length times width.

Most Marco yards will need at least one pallet (75 to 80 bags) of mulch to cover their gardens. Larger yards can use several more pallets. It is a common site to see the landscape suppliers hauling pallets of mulch around the island. Let the mulching begin!

A final alert. The Spiraling Whitefly has had a serious outbreak on Marco Island in the last two weeks. The Ficus Whitefly has also been causing a lot of trouble with ficus hedges on Marco this year. Look around and you will see many defoliated ficus hedges. The spiraling whitefly is different. It does not cause the severe plant damage or branch die back of its predecessor the ficus whitefly. Look for white spirals or circular patterns on the undersides of the leaves. There will be a buildup of a white, waxy substance as well. This waxy buildup can build up to amounts so great it begins to drip off the affected plants and onto cars, patios and pools causing a sticky mess. This honeydew is actually the insect's excrement and can turn into what is referred to as sooty mold which will then turn black. This whitefly is huge compared to other whitefly species and so causes extreme amount of sooty mold. The outbreak is so bad you can see them flying around in areas of infestation, which is most everywhere, and it looks like snowflakes or fire soot falling from the sky. My pool has a coating of them floating on the surface!

The best thing to do when you first discover you have this whitefly is to try and wash as much off the plant as possible with a strong stream of water. Follow this with a treatment of systemic insecticides like Merit or ask at the garden center. These can be applied as a spray to the foliage, a drench of the roots or trunk injection. You can treat with an insecticidal soap or horticultural oil but you will have to reapply once a week for approximately a month for complete control. The systemic insecticides will once again last for up to a year.

For pictures of both of these insects visit the University of Florida, IFAS Extension web site.

Eileen Ward and her husband Peter have owned and operated Greensward of Marco, Inc., a lawn maintenance and landscaping company since 1981.

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