By Val Whitmyre, U.C. Master Gardener

Penstemon

Perennials, by definition, do not have an annual life cycle. Annual

Gaura

Some perennials, such as agapanthus or fortnight lilies, have been called freeway plants or gas station plants because they bloom dependably even with continual gas fumes and other abuse. I think they are the perfect plants for the gardener who can't be bothered with constant watering or spraying. They're evergreen, and snails and slugs don't eat them. Snails do reside in agapanthus leaves, but that's okay. At least you know where to dump the bait.

Some perennials continue growing throughout our mild winters, but most will die back to the ground each winter with new growth emerging from the crown in spring. Some, like bulbs and irises, die back but store enough energy in their bulbous roots to enable them to survive the winter.

Many perennials can be almost carefree if you remember three important things. Plant them in soil that has good drainage, a must for most plants. Give them room to breathe; they like good air circulation. And don't water them too often.

When planting, dig the hole slightly deeper and wider than the container. Break up the soil and mix in about 10 percent compost or other amendment. Water the hole well the night before you plant, then situate the plant about an inch above the ground level. Mulch all around the plant with well-aged manure, keeping the manure away from the main stem. Mulch will keep the soil cool, help keep weeds down and feed the plant as the mulch decomposes. Most perennials aren't bothered too much by pests or diseases.

Some favorites in my yard are Tagetes lemmonii, or Copper Canyon daisy, a lacy, four-foot plant whose foliage smells like mint, lemon and marigolds. Kangaroo paw (Anigozanthos), an Australian native, sends up tall, arching stems with fuzzy flowers in red, yellow or pink. Verbena bonariensis has the same tall stem growth with large basal leaves. The lavender flower clusters look good bobbing between rose bushes. It's known as the "see-through plant" because you only notice the flowers. Winter-blooming hellebores have dusky, mysterious-looking cup-shaped flowers in various colors. Some have unusual striped basal leaves. This plant likes filtered shade.

Most perennials grow large after a few years and may then be divided into several plants. Some pull apart easily after their roots have been immersed in water. Others, like agapanthus, can be chopped with an axe or pried apart to gain at least three new plants. Throw the old center of the plant into the yard-waste bin.

When perennials finish their bloom, prune back spent flowers and stems to the basal growth to keep the plant energized and encourage new growth.

If you would like to have new plants for nothing other than a little elbow grease, then perennials are for you. Year after year, you can divide them and redesign your landscape or give them to neighbors and friends. There are hundreds of different species, for both shade and sun. Call the Napa County Master Gardener office and ask for a list, or visit a local nursery where the employees will be happy to help you.