UNITED STATES—Gardening is unnatural. Most popular plant species are not naturally native. Cultivars are products of unnatural selection and breeding. Most plants like unnatural watering. Some enjoy unnatural fertilizers. Removal of their detritus is unnatural. So is the replacement of their detritus with mulch. Actually, most of what happens in the garden is quite unnatural.

Ironically, gardening is how many of us incorporate more nature into our lifestyles. Much of our effort compensates for what plants naturally crave, but unnaturally lack. Watering is necessary for plants that get rain through summer within their natural ecosystems. Mulch might be nice for plants that naturally benefit from the decomposition of their own debris.

In nature, most plants benefit from their own debris. They enjoy the nutritiously decaying organic matter and enhanced moisture retention. Their shallow roots enjoy the insulating effect on the surface of the soil. Debris of some plants excludes other competitive plants. Mulch is not a perfect substitute for such detritus, but partly compensates for its removal.

Mulch is more appealing than natural detritus.

Although it would likely be an asset to the plants that produce it, the detritus produced by most plants cannot stay in the garden. Much of it is too abundant. Some are too shabby or too coarsely textured. Some might become combustible as it accumulates. Diseases can overwinter in some types of debris. Mulch is more sanitary, neater and less combustible.

Most mulches are organic matter of one sort or another. Compost does not last long as a mulch, but is appreciated by most plants. Uncomposted chips from a tree service occupy nitrogen as they decompose, but are more effective for inhibiting weed growth. Products that are available as mulch at garden centers are more refined, but also more expensive.

Some dense ground cover plants perform something like mulches. Many consume more moisture than they retain though. Also, they can retain bits of potentially infectious debris that falls from diseased plants above. Nonetheless, they insulate the surface of their soil, and inhibit or exclude weeds. Gravel over ground cloth is inert, but requires no watering.

Highlight: Rosemary

It is as familiar for culinary application as it is for home gardens, even with its new name. Rosmarinus officinalis is now known as Salvia rosmarinus, but the common name is still just rosemary. Like many Mediterranean culinary herbs, it is a member of the Lamiaceae Family. Since it is native to Mediterranean regions, it is quite happy within local climates.

While many culinary cultivars of rosemary are shrubby or upright, the most popular home garden cultivars are trailing types. Trailing rosemary disperses its woody stems laterally, but can eventually get deeper than two feet. Shrubbier cultivars get at least twice as high in less time. The finely textured dark green foliage is evergreen and pungently aromatic.

Bloom is generally most profuse from late spring through the middle of summer, but may never really stop. It can continue in sparser sporadic phases whenever the weather gets warm, and even throughout the year. The tiny flowers are various shades of blue. Purple, white and pale pink bloom is very rare. Bloom is appealing to bees and other pollinators, including hummingbirds.

Horticulturist Tony Tomeo can be contacted at tonytomeo.com.