Many garden enthusiasts perform all the procedures necessary to maintain their gardens. Some of us employ gardeners to simply maintain the lawn. Others want additional chores attended to as well, such as shearing of hedges. Regardless of the extent of the tasks assigned, maintenance gardeners often require some maintenance themselves.

Excessive irrigation is the most common innate problem among trees within landscapes maintained by gardeners. Some landscapes are so saturated that puddles linger long enough for algae to grow. No kidding: I must wear boots without tread to avoid leaving such sites with bits of the lawn attached. Soil saturation indirectly promotes development of shallow and buttressed tree roots by inhibiting development of deep roots. Excessive moisture promotes decay among mature roots, particularly among those of old native oaks that had not been subjected to irrigation prior to installation of the landscape.

Irrigation is so often excessive because the problems it causes are not as apparent as the desiccation that may occur if irrigation is insufficient. For example, clients may not see shallow roots or decay below the surface of the soil, but cannot miss a brown lawn.

An irrigation schedule cannot be prescribed, but must be determined by the unique environmental conditions of each site. If the shallow root system of lawns necessitates frequent irrigation, it should not be applied so generously that the soil is continually saturated. Areas that are landscaped with more deeply rooted species certainly do not need to be irrigated as frequently, so should not be assigned the same irrigation schedule that a lawn requires, as is typically done by gardeners.

Gardeners are generally very efficient with lawnmowers, edgers, blowers and most of all—the dreaded hedge shears. They seem to compete by shearing species that are less conducive to shearing than those their colleagues have previously sheared. Consequently, many items that should develop into small trees, vines or freeform shrubbery are indiscriminately sheared into rigid, nondescript forms. Clients may need to protect some of such items so that they may develop as intended. An "efficient" weed-whip is not as common, but can be fatal.

Those who are interested in visiting a garden that completely lacks gardeners and features many naturally structured small Japanese maples and blooming rhododendrons will be happy to know that the open house at Bay Laurel Nursery will continue for two more Saturdays, May 1 and 8. Located at 1554 Bean Creek Road in Scotts Valley, the nursery specializes in rhododendrons, azaleas and pieris and will be open between 10 a.m. and 5 p.m.

Perennial of the Week: Aeonium arboreum

I would not have guessed that Aeonium arboreum is in the family Crassulaceae and is therefore related to jade plant. Instead of pairs of succulent leaves separated by obvious internodes, the pale foliage of Aeonium arboreum is flattened and compressed in dense "rosettes" that may be as wide as 8 inches. Weight of the foliage usually holds stems near to the ground, but mature specimens may be as high as 2 ¹/2 feet. If unadorned foliage is preferred, the interesting yellow floral trusses may be removed before they develop.

The dark purple Aeonium cultivar "atropurpureum" is the most popular. "Zwartkop" has even darker foliage. This species is more common and happiest in coastal areas, but can be accommodated in the Santa Clara Valley if partially shaded. It is not very common here, but is occasionally found at garden shows where exotic species are exhibited.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.