A nice way to make the onerous chore of weeding more appealing is to call it gardening. At least, it sounds better.

At this time of year, there is a whole-lot of gardening to be done, but a little planning and good timing can reduce the hard labor and give us more time for the more rewarding kinds of gardening.

The current crop of weeds began last fall, when autumn rains brought up the annual cool-season grasses and other plants that make much of California green in the winter. Those cool green plants grew slowly through this winter's short days and cold temperatures. They are exploding into vigorous growth and seed production as the days lengthen and temperatures increase. Later this spring, additional warm-season weed seeds will begin to germinate.

As dealing with the weeds becomes more urgent, we need to make some crucial choices. What methods make the most efficient use of our time? Which weeds can be sufficiently controlled simply by mowing them down? Should I use herbicides? What effects might they have on my trees, shrubs and the environment?

The world of weeds and weed control is complex. There are perennial grasses, annual cool-season grasses, annual warm-season grasses, broadleaf annuals and perennials and woody-plant weeds. Any of these might appear in a variety of locations ranging from cracks in a paved parking area, to a flowerbed, a lawn or under the canopy of a tree. For safe and sensible control, we need to consider not only the target plant, but also potential non-target victims of our well-intentioned attempts at weed control.

Because weed control is so challenging, gardeners and garden product manufacturers have come up with a long list of methods and products for weed control, which further complicates things.

Physical and mechanical controls include mowing, pulling, cultivating, mulching (smothering with wood chips, fabric, poly sheeting, newspaper), solarizing (killing weed seedlings via solar radiation under poly sheeting), flaming, dousing with hot water and other heat treatments like the Eco Weeder (propane /ceramic heating element), or the Waipuna hot foam method (resembling a carpet cleaning system mounted in a van) and browsing by sheep or goats.

Checking the shelves of a local garden center, I counted and made notes on about 18 different weed killers. Addressing the complexity of weed types, herbicides range from soil sterilants and preemergents (seedling preventers), to selective grass killers, selective broadleaf killers and non-selective systemic herbicides. The best-known example of the latter is glyphosate, the active ingredient in Roundup and Kleenup. Herbicides are designed to do damage to certain undesired plants, but they can also damage or kill desirable plants and have unintended effects on people, animals and aquatic life. They all have the potential to do serious damage if they are used improperly.

Let's focus on weed control around trees and other woody plants.

It's crucial to keep a few principles in mind:

* Most of the absorbing roots of trees and other woody plants grow near the soil surface and well beyond the spread of the branches. This makes them susceptible to damage by chemicals and the physical disruption of cultivation.

* Like leaves, young stems and thin bark can absorb chemicals into a plant's system.

* Trees (except for palms and other monocots) are "broadleaf" plants in terms of susceptibility to herbicides.

* Pesticide labels give directions for timing and application rates have been carefully worked out for safety and effectiveness. Don't experiment!

* The harmful effects of herbicides may not be immediately visible in the plants or the environment.

When I posted an invitation to consulting arborists on the ASCA on-line discussion list to share comments about weed control around trees, I got an interesting response about Roundup, a longtime, favorite, non-selective systemic herbicide. It came from an arborist in the Portland area. His experience has shown that the careless use of Roundup may kill young trees and ivy. Where gardeners apply it freely, thinking it won't hurt trees or that ivy is resistant to it, it may build up in the plant's system over the course of several applications until a threshold of concentration is reached and the plant dies or loses vigor.

At a conference I attended a few years ago, I recall one of the speakers mentioning that Roundup -- although it rendered inactive by contact with soil particles -- may remain active in mulch and may be absorbed by roots that grow into contact with it. He also said Roundup can moved from one plant to another through soil fungi.

Herbicides can be great time-savers, but they can also have serious unintended consequences.

So, what's the best use of our time for weed control? It's probably in efforts to prevent weeds from getting started. For annual weeds that readily reseed, cut them down or pull them out before they set and release seed. That time is here, or fast approaching, for many of our annual weeds.

Assuming there will always be plentiful weed seeds in the soil, prevent them from sprouting by covering the soil with a thick layer of mulch. For added effectiveness, add a layer of weed control fabric or several layers of black-and-white newspaper as a weed barrier. Remember, mulch is beneficial to tree and shrub roots and soil organisms. Weed barriers can be sandwiched between layers of mulch to allow the mulch to be in direct contact with the soil. If you try this, be careful with irrigation and monitor to be sure it penetrates through the layers and into the soil. Avoid the long-term use of poly sheeting as a weed barrier. It prevents the normal irrigation and gas exchange that are needed for healthy soil.

For tough, established perennial weeds such as Bermudagrass, you'll need to thoroughly dig them out without leaving pieces in the soil, smother them with a secure barrier and/or use an herbicide, like Roundup, with appropriate caution.

For those using or planning to use herbicides (I admit, I have applied lots of Roundup over the years), keep a few cautions in mind: Mix and apply at the rate given on the label for the particular task at hand. When spraying liquid herbicides, use low pressure to generate large drops of spray, rather than mist that may drift to non-target areas on the slightest air movement. Keep the spray wand low and consider using a spray-wand hood or sheet of cardboard or stiff plastic as a barrier to stop the spray from hitting the bark, stems and low foliage of trees and shrubs.

Bill Pramuk is an ASCA registered consulting arborist. Please send questions to bpramuk@pacbell.net)