Planting Bulbs

By Jackie Gitman, U. C. Master Gardener

Fall is the season for planting bulbs. They are one of the easiest herbaceous ornamentals to grow as they require little or no care after planting. They come back year after year, and they provide color in difficult areas. I know some gardeners who plant nothing else because bulbs are so carefree.

The word "bulb" is used generically for a variety of plants that may not be bulbs botanically. Some are corms, rhizomes, tubers or tuberous roots. All have underground organs that store food for the plant. Examples include the familiar narcissus (daffodils), crocus, hyacinth, grape hyacinth and tulips, all of which are hardy and may be planted in the fall.

The more tender bulbs, corms and tubers generally bloom in late spring and early summer and do not survive severe winter cold. However, many hardy and tender bulbs do well in the Napa Valley. You can count on local nurseries to carry the types that perform well here. If you cannot plant them immediately, keep them in a paper bag in a cool place.

Bulbs may be planted under trees, in shady areas, among other perennials or alone in pots or other containers. Choose a site with good drainage as bulbs do not like wet soil. However, the roots do need moisture to grow. Check with your nursery or read the package instructions to determine planting depth. Bulbs are picky about planting depth so follow directions precisely. Fertilize the soil before planting. Some gardeners sprinkle a little bone meal in the planting hole.

Paperwhites (a type of narcissus) can be forced to bloom in a three- to four-inch-deep decorative container that does not have drainage holes. To force bloom, put one to two inches of washed gravel or stones in the bottom of the container. Place several bulbs closely together on the gravel. Add enough gravel over or around the bulbs to hold them in place. Add enough water to reach the base of the bulbs and maintain it at this level. Do not immerse the bulbs in water; only the basal (root) plate should be in water.

Paperwhites will flower under any light conditions. However, for best results, place them in a window area with a southern exposure until they begin to flower. Then transfer them to the coolest part of your house, away from direct sunlight. This helps to prolong flowering.

A few more tips for good results:

• Plant bulbs that bloom at different times to enjoy color from spring through early summer. Check the bulb packages or ask nursery staff for help in selecting bulbs with different bloom times.
• Bulbs look better in masses than in groups of two or three. Use them to fill in bare spots in early spring before perennials come out of dormancy.
• Propagate bulbs and corms every two to three years by separating the bulblets and cormels where they detach naturally.

There is nothing more satisfying than seeing your hard work in the fall pay off in a blaze of spring color from blooming bulbs.