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Drought teaches benefits of mulch

As grassy lawns of necessity give way to dressed flowerbeds, gardeners can find plentiful sources of water-preserving mulch right in their own back yards.

This year's long cycle of drought in Florida's climate, be it caused by global warming or nature's own rhythm, has been a strict teacher. That nature is the boss has been the biggest lesson. We can't easily reduce the population or reverse deforestation, but we can learn how to reduce water use and make the best of what we are blessed with.

Plentiful water decades ago made lawn worship possible and fashionable, but this drought has inspired many of us to replace vast swaths of thirsty St. Augustine lawn with colorful beds of subtropical perennials attractive to the eye, birds and butterflies. Nothing benefits a landscape garden more than a deep layer of mulch that keeps the soil beneath it damp, cool, fertile and teeming with earthworms and other beneficial critters.

Red mulches are primarily decorative, best used as a top dressing over a truly functional organic mulch 6 inches to 8 inches deep. As our landscapes become more Florida-friendly, many folks are coming to prefer the more natural-looking mulches that truly heal our sandy soil and usually are much less expensive, even free.

My favorite is the chipped tree branches delivered for free or for a small delivery fee by tree-trimming companies ever since state law forbade dumping it in landfills, where it releases "greenhouse gases" underground. Above ground, it decays into a rich humus that improves our sandy soil while doing wonders to keep it moist and alive.

Order it in summer to get a mulch rich in pulverized nitrogen-rich green leaves, which help minimize the period of nitrogen deficiency a wood-based mulch can trigger as it decays. Applied 8 inches thick, this mulch will soon settle into a layer 6 inches deep that smothers out annual weeds while trapping summer's monsoon moisture in the soil beneath.

A summer mulch application is thus a "bank account" that saves up water in the soil for later use. Organic fertilizers such as fish meal or manure can be spread right on top of such a thick mulch layer, where they will leach their nutrients steadily and help the mulch decay into a rich, spongy layer like we see on the floor of an old-growth forest.

Decaying wood forms lignin, a remarkable soil component that holds many times its weight in water, while harboring beneficial organisms. If you've ever encountered a fallen log in the woods that was so old and soft you could crush it with your hand, you've met the lignin our soil sorely lacks. Chipped tree mulch is the easiest way to add it.

Horse stall sweepings, a mixture of sawdust, horse manure and horse urine, make up another wonderful mulch, usually free for the taking from stables. The animal waste is loaded with beneficial bacteria and nutrients, especially nitrogen; the sawdust decays into lignin; and applied to a depth of 4 to 6 inches, this mulch will do wonders for impoverished soil, especially for a vegetable or rose garden. Horse manure may carry the tetanus germ, which could enter a puncture wound, so be sure to keep your inoculations up to date.

Late each winter, we see countless bags of oak leaves out on curbs on garbage day. A pity: They make excellent mulch. Granted, it's not the prettiest you'll see, but the leaves decay into a rich, acid-forming substance that coastal folks can use to combat the excess alkalinity of beachside soils. Inland, that acid will be counteracted

Mulch from 3D

by your annual spring sprinkling of dolomite. Spread out several bags of leaves each week for the two months or so they are available, and you will have deeply mulched all your landscape beds for free.

You may already have seen just how many earthworms will live in decaying oak leaves as they transform into the black humus our soil needs. Why buy black peat when free leaves will do the job?

If your lawn is organic, use your mower to harvest pesticide-free clippings every other mowing. (The lawn needs some to decay into compost.) The fresh, green nitrogen-rich organic grass clippings make excellent garden mulch. I also use them in my potted plants as a 2-inch mulch to reduce drying of that small mass of soil, especially in hanging baskets. Veggie gardeners will quickly get addicted to this especially rich and free mulch source too often discarded on garbage day.

In 17 years of landscaping in Central Florida, and nearly 30 years of gardening in this area, I have not once used cypress mulch and never will. Why? There is longstanding evidence that natural fungicides in it suppress beneficial soil fungi that foster soil fertility and health, plus it does little to trap moisture or add humus. In addition, much of it is obtained by grinding up what little remains of Florida's formerly majestic cypress forests. Sure, it is pretty when it's brand new, but if it doesn't heal and protect your soil, why spend money on it?

Gardening pioneer Ruth Stout advocated very thick mulches way back in the '50s and lectured globally on that topic, especially in dry regions such as the Middle East. Our drought has made her lessons all the more appropriate for us. She favored straw and hay mulches, and I have used coastal hay as a thick, spongy mulch for many years.

Just buy the bales at a feed store, cut the strings and spread the thick slabs of hay each bale separates into by "tiling" the garden with them. These slabs of densely packed hay are easy to position around existing plants. Coastal hay decays quickly into black, earthwormy humus, so reapply it annually. Stout promoted hay mulches primarily for veggie gardens, and that is a good place to try out coastal hay as a mulch.

I keep hearing mixed reviews about eucalyptus mulch. Having tried it a few times, I have yet to see it as more than decorative. Enviro Mulch is another new mulch: I understand it is composed of ground-up melaleuca trees being purged from the Everglades. If so, it would be another recycled mulch vs. one made from a standing forest.

Pine bark mulches are a byproduct of the logging industry and are said to harbor termites. They, too, are decorative and seem to do little to protect and improve our sandy soils. Redwoodnuggets are expensive, float away in our summer rains and are a byproduct of the continued plundering of this country's now tiny surviving stands of redwood trees. By now, you see why chipped tree trimmings are my favorite mulch.

As a native Floridian I dread the annual drought, now made worse by a long drought cycle in our climate, and thus cannot imagine gardening without a thick mulch. Watering restrictions have taught most of us that times have changed and that our landscapes need to change, too.

Would you rather mow a huge lawn dozens of times a year, or mulch beautiful beds of perennial flowers once a year and get much lower water bills all year long?

John A. Starnes Jr. is an avid gardener and rosarian who studies, collects, cultivates and hybridizes roses for the diverse regions of Florida and Colorado. He can be reached at THE.GARDEN-DOCTORworldnet.