It's spring - now's the time to think about flowers and shrubs

The best garden reference books offer more than you expect. In the new edition of "Taylor's Guide to Perennials" (Houghton Mifflin, $23), Barbara Ellis suggests a new way of looking at these popular flowering plants.

Gardeners often turn to perennials because the plants come back year after year and they have to be planted only once, instead of every year, as annuals do. But have you ever thought of perennials as "agents of change" in your yard, counteracting a dull and static appearance?

"A perennial garden changes from day to day, week to week, and month to month," Ms. Ellis writes. "Perennials provide an ever-changing parade of color and form from early spring right on up to the first killing frost of fall."

With so many types - from iris to chrysanthemum, daylily to fern - how do you choose the right ones for your garden?

It's simple, she says. Match the plant to the site. This means learning the conditions in your yard: Is the soil damp and heavy or rich and loamy? Is the spot where you want to plant in the sun all day, shady in morning, or does it receive dappled sun through tree limbs?

Once you're familiar with the conditions in your garden, then you can use the encyclopedia section of "Taylor's Guide to Perennials," which covers more than 600 plants in detail, to find the right plants for any spot.

The new edition of "Taylor's Guide to Shrubs" (Houghton Mifflin, $23), by Kathleen Fisher, is laid out much like the sister volume on flowers - plenty of good-sized color photographs and comprehensive, easy-to-access information.

But it also offers "added value" beyond the listings of more than 500 shrubs. For instance, Ms. Fisher discusses invasive plants that are crowding out native species in the wild.

Rather than issuing an all-encompassing condemnation, she points out that while Scotch broom may be a weed in California, it's not in New England. Then she provides species name, problem area, and risk level. Did you know that butterfly bush is a moderate-risk invasive plant in the mid-Atlantic and Pacific Northwest?

Like her fellow author, Fisher suggests that readers think about shrubs from a slightly different angle. There's no rule that says you have to use shrubs around the foundation of your house, but if you want to, she recommends giving a mixture of perennials and dwarf shrubs a try.

And why not mass shrubs as you do marigolds? Especially effective in groupings are shrubs that provide bright fall or winter color, she mentions - also low-growing, wide-spreading shrubs to cover bare spots.

Both these books deserve prominent shelf space in the library of every gardener.

(c) Copyright 2001. The Christian Science Monitor