A Gulf Coast summer afternoon can drop an inch of rain in twenty minutes. Beds built the inland way — mulch spread on flat ground with plastic edging — simply relocate themselves into the lawn by July. Building beds for this climate is a design job.
Why beds fail here
Three forces gang up: downpours that move loose material, sandy soil that offers mulch nothing to settle into, and summer humidity that composts thin mulch layers at double speed. The result is the annual ritual: buy mulch, spread mulch, watch mulch leave.
Bed design that holds
Real edges. A defined edge — steel, stone, thick commercial-grade border, or a properly cut trench edge maintained at depth — is what physically stops migration. The flimsy plastic strip from the garden center loses to the first real storm.
Correct depth, not maximum depth. A settled two-to-three-inch layer locks together and sheds rain around plants; piles deeper than that stay fluffy and float. And never mounded against trunks and stems — volcano mulching holds humid-climate moisture exactly where it rots plants.
Slight grading inside the bed. Beds pitched so water moves through them slowly, rather than pooling or sheeting, keep both mulch and plantings healthier in storm season.
The right mulch for the spot. Pine straw knits together and grips on any slope — there's a reason it's everywhere in the South. Larger bark nuggets resist floating in flat beds. Fine shredded mulch looks tidy but travels most.
Beds like this pair naturally with salt-tolerant plantings and drip irrigation, which waters plants without blasting mulch. It's all part of the landscaping service.