Negligence of irrigation of plants that are sheltered from rain is as common as failure to disable automated irrigation. Fortunately, cool and damp air limit evapotranspiration (evaporation from foliar surfaces) and evaporation from the surface of the soil, which would otherwise desiccate plants deprived of moisture. Most species are so groggy and inactive during dormancy that they are not easily damaged by desiccation anyway. However, plants in planter boxes or portions of the landscape under eaves or lanais may occasionally require irrigation nonetheless.

In my garden, a planter box containing geraniums and nasturtiums, as well as several potted palms under the eave of the garage in back, require supplemental irrigation through winter. I water the planter box less often than once a week, and perhaps only twice monthly, just to keep the geraniums and nasturtiums alive until spring. I do not think they would appreciate any more. They have never expressed want for more by dropping or discoloring foliage. However, the palms should be watered at least weekly because they are more exposed to sunlight and breezes that enhance evapotranspiration, and their roots are confined to proportionately less potting medium. Not only do they use more moisture, but they also have less medium from which to take moisture.

The potted palms also need more frequent irrigation because they were the victims of my recent indulgence in prissy flowering annuals that I would not want anyone to see in the front garden. I planted purple stock and pansies instead of my favorite white, so it looks as if my neighbors, who prefer purple, planted them. Stock can actually be a perennial in cool shaded areas of a garden, but will eventually succumb to summer heat so close to the driveway.

The various primroses and sweet Williams are other "perennial" flowering annuals that will happily bloom through winter. Nemesia, schizanthus, Iceland poppy and viola are seasonal "annual" annuals. My "neighbors' " purple pansies are actually a type of viola. Seed for cool season vegetables, such as beet (yum!), carrot (ick!), radish, turnip, lettuce, spinach, chard and onion can be sown anytime through winter.

Berries of the Week: Toyon

When there is not much to eat during winter, birds enjoy toyon berries, Heteromeles arbutifolia, like those of related firethorn or cotoneaster. The rusty red, or very rarely orange-yellow, clusters of berries ripened in autumn and will soon be mostly eaten. The flat-topped clusters of white flowers that bloom in summer are popular with bees. Occasional light pruning promotes bloom and subsequent fruit. The 3-inch-long leaves are slightly serrate.

Toyon, also known as Christmas berry or California holly, is native to the foothills of the Sierra Nevada and Coast Ranges, including the Santa Cruz Mountains and the Diablo Range that surround the Santa Clara Valley. It can be seen growing along Highway 17, both in the wild and where it has been planted in the unrefined and naturalized landscape of the Los Gatos Creek Trail. It is obviously drought tolerant, but blooms and fruits more profusely and is more densely foliated if irrigated during summer. It can be quite happy within an irrigated garden if soil drains well and irrigation is not excessive.

Toyon is most commonly grown as a screening evergreen shrub less than 8 feet tall, but can be as high as 20 feet if lower growth is pruned away to expose several trunks, forming a small tree. Single trunks may be inadequate to support a large canopy, and look unnatural for toyon anyway. Full sun exposure is preferred. Light shade is easily tolerated, but inhibits bloom, fruit and foliar density.

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