September 4, 2010
D. F. Braun
There is confusion about the definition, but biennials are not plants that bloom every other year. Individual plants in this category do have some peculiar flowering habits. Technically they are all plants that require two full seasons to mature, building up their reserves of leaves and roots for the first year and flowering the second. An annual plant will complete its life cycle in a single growing season. A perennial plant persists from year to year and produces flowers and fruit in two or more different years. There are many variations of this schedule. Let's look at a few examples.
Biennials are some of the most treasured plants in our gardens; they are loved not for their rarity but for their homey, simple charm. They are considered "cottage garden flowers": foxglove, forget-me-not, hollyhocks and sweet William are among the most notable. Yet, despite of the tug at the heart of these cherished plants many gardeners avoid them because most require much more effort than any annual. The marigold can be expected to give two to three months of nonstop blooms. Usually lacking time and space, and desiring long-lasting color in our summer garden, we opt for impatiens or petunias. And why not? They are predictable in their profusion. Biennials, on the other hand, are far less dependable. Those magnificent foxgloves may look as though they have had a dreadful hangover in mid-summer when you expect your garden to look its best. But let me plead their case. Think of some of the advantages of these beauties.
Forget-me-nots will colorize almost anywhere a reasonable amount of ground is kept clear by light cultivation. Even as infant plants they are appealing with their fuzzy green, mouse ears and thick clusters of limpid blue buds in early spring. In an acid soil they are pale blue and with a little more lime they are a deep cerulean. Either way there is nothing more winsome. Older gardeners consider forget-me-nots as instruments that can measure the health of their gardens.
Among biennials the foxglove is probably the reigning queen, not just for the cunning shape of each flower, but for the vertical rods of bloom with their mystical interiors. The genus Digitalis, to which all foxgloves belong, has many wonderful plants, but the most beloved is Digitalis purpurea, which is native to much of northern and central Europe and most popular with English gardeners.
Add to this list the old fashioned hollyhocks, perhaps 7 feet tall against a fence or wall (and pick your color). While many varieties may be subject to rust, Alcea ficifolia and Alcea pallida though not as varied in color or height are rust resistant. 'Dame's rocket' likes a partly shady spot and bears a candelabra of little, four-petaled flowers in beautiful shades of purple, pink and white. The fragrance is better than fresh laundry.
Lack of space rather than patience may be one reason to resist growing biennials. An easy solution is to buy young plants in their second year of growth. Forget-me-nots, foxgloves and even hollyhocks transplant readily, if a generous amount of earth is provided for each plant. Ideal conditions for transplanting would be a cool, damp day.
It is probably only fair to say that biennials will always grow in country gardens not given to too much tidying up. For they are far from the manicured, crisp-edged suburban gardens as one can possibly get. The values they carry of ease, abundance and a lightness of heart are comparable to old shade trees and the bulbs that surprise us each spring with their fresh bouquets. They all seem to say, "We have been here a long time, and we will be here a while more." In any garden that is a voice to be treasured.
Biennials may be a sort of benchmark of the committed gardener whose motto might be: "Think how beautiful they will be ... next year.”
The University of California Marin Master Gardeners are sponsored by UC Cooperative Extension. For questions about gardening, plant pests or diseases, call 499-4204 from 9 a.m. to noon, and 1 to 4 p.m. weekdays, or bring in samples or pictures to 1682 Novato Blvd., Suite 150B, Novato.