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Letter to the editor

Not just sea oats thrive in beach gardens

Salt and alkalinity may challenge the seaside gardener, but a green oasis is within reach.

By John A. Starnes Jr., Special to the Times
Published September 8, 2007

That romantic sea spray and alkaline beach sand thwart the best efforts of even seasoned gardeners, who simply want a presentable lawn, colorful landscape beds and a productive vegetable garden.

In a past story I addressed one approach: growing salt-tolerant plants. But lots of gardeners want to grow other things. What about them?

Transform the soil. Work with natural materials that add acids, leach salt, and add water-holding organic matter. Soon you'll enjoy a tantalizing taste of successful seaside gardening.

Central to this approach is applying a deep mulch once or twice a year, at least 6 inches thick each time. Excellent choices include bagged oak leaves, which are already acidic; a big load of chipped limbs and leaves delivered by a tree-trimming company; and manure and sawdust bedding, free at local stables.

All organic matter generates natural acids as it decays. Summer rains wash those acids deep into the sand and balance the excess alkalinity that makes plants struggle. Soon that loose sand will darken and enrich and begin to hold water. Then it can support our gardening allies, earthworms, who till the soil and enrich it for us. Mulch those landscape beds and gardens.

Powdered gypsum can be tricky to find in bags larger than 5 pounds, but this natural mineral calcium sulfate is unsurpassed for helping to leach salt out of soil. Sprinkle it on once or twice a year, especially after a hurricane or other major storm has splashed saltwater all over the landscape.

Chunks of broken-up gypsum wallboard can be scavenged from a construction site with the permission of the foreman. Or buy whole sheets at the hardware store and break them up. Place a few hand-size pieces at the bottom of the hole when planting new perennials and shrubs, and their roots will mingle with this built-in defense against salt buildup.

Bermuda grass is the best choice for beachside lawns. Municipalities and hotels sod it into playgrounds and parks where, even with no care, it looks surprisingly good. But fed every March, July, September and December with cottonseed meal, Bermuda grass will become lusher and greener than you thought possible for a lawn by the beach, yet remain amazingly drought-tolerant.

Sold in 50-pound bags by feed stores, cottonseed meal is a potent natural acidifier that also supplies nitrogen, phosphorus and potassium in abundance if sprinkled on lawns and beds as heavily as you'd put Parmesan cheese on spaghetti. It is a non-burning natural soil food perfect for healing seaside soils. And contrary to belief, your Bermuda lawn can be mowed with a conventional rotary mower.

Each November, apply winter rye grass seed to your dormant Bermuda lawn for a quick greenup that will add organic matter to the soil when it dies and decays each spring. Mowing with the bag off your mower all year long will allow the clippings to decay and nourish the sandy soil as a form of mulch. Once again, as it decays, the natural acids it releases will steadily combat alkalinity.

If you can't find cottonseed meal at feed stores and are comfortable with chemical fertilizers (they too tend to acidify alkaline soils), feed the Bermuda four times a year with either Sunniland Palm 8-6-6 (if you rarely water) or something along the lines of Lesco 16-4-8 (if you irrigate frequently) to provide ample nitrogen, phosphorus and potassium plus trace elements like manganese, iron, magnesium, boron, molybdenum, zinc, copper and sulfur.

The natural mineral sulfur is sold in 5-pound bags at garden centers. Sprinkled lightly atop your thick mulch layer each spring, it will quickly acidify the soil when the summer rains come. At last your pale, sickly ixoras, gardenias, hollies and azaleas can perk up. That Parmesan cheese analogy will help you decide how much to use.

Iron sulfate works even faster. Apply it more sparingly, like salt on food, because it is potent. Keep it away from concrete surfaces, which it will stain rusty red-brown. But boy, does it work on yellowing plants.

Successful seaside gardening can be a part of your parcel of paradise if we change salty sand into soil.

John A. Starnes Jr., born in Key West, is an avid organic gardener and rosarian who studies, collects, cultivates and hybridizes roses for Florida. He can be reached at johnastarnes@msn.com.

[Last modified September 6, 2007, 17:08:19]