Bulbs

Planning to plant spring-flowering bulbs provides gardeners a welcome hint of another season with all its beauty and freshness when most of the garden is spent and tired-looking. From late August through October, garden centers start selling spring bulbs—crocus, daffodils, hyacinths, tulips, and more!

Bulbs are often the easiest flowers to grow, and some choices will reward your initial investment for years with color, scent, and blossoms. Once properly planted, bulbs need minimal care. Some, such as daffodils (Narcissus), will naturalize and provide an expanding color display.

Two categories of bulbs
Plant spring-flowering bulbs, such as crocus, daffodils, hyacinths, and tulips, in the fall before the ground freezes. Most of these bulbs require a 12- to 16-week period of chilling to produce flowers and before breaking dormancy.  Planting dates for Zone 6 are no earlier than October; for Zone 7, it is November through early December.

Purchase summer/fall-flowering bulbs, such as caladiums, cannas, dahlias, gladioli, and lilies, in the spring and plant after danger of late frost, when the soil temperature is above 55-60ºF or they may rot before sprouting. Unlike spring-flowering bulbs, chilling or a prolonged cold period will damage or even kill them.

Selecting and storing bulbs
Look for the largest bulbs available. Choose those that are firm and have no mold or obvious bruising. Store the bulbs until planting in a cool, dry area away from fruits—which produce ethylene gas that prevents blooming and may cause flower abnormalities.

Planting bulbs
Plant bulbs in a partial- to full-sun area. Because much of their growth is completed before deciduous trees and shrubs leaf out, bulbs can be planted underneath to lovely effect. Plant in sweeping groups instead of singly or in rows. If space is limited, you can plant bulbs in containers or window boxes.

As with any planting, proper soil preparation is important and good drainage is essential. Getting the soil right is probably the most important step to ensure gardening success. Bulbs do best in soil with a pH of 6 to 7. Fertilize and lime according to a soil test.

Plant bulbs with their root plate facing down and the nose of the bulb facing upward. Planting depth is important, too. As a general rule, plant bulbs at a depth of 3 times the bulb’s width. Tulips and narcissus will typically need to be planted 8-inches deep; smaller bulbs such as snowdrops and crocus about 3- to 4-inches deep.

Plant snowdrops immediately, but wait to plant daffodils until October or November. Keep other spring-flowering bulbs until the soil temperature at the planting depth is below 60ºF.

Cover the bulb with soil, then water to settle the soil and provide moisture to encourage rooting. Rain usually provides enough moisture for spring-flowering bulbs, but additional watering may prolong bloom during a hot or dry spring. Mulching with organic matter, such as pine bark or shredded leaves, helps maintain moisture and an even temperature, as well as enriching the soil.

Critter-resistant bulbs
Narcissus and allium are generally safe from the appetites of voles, squirrels, and deer, while tulips and hyacinths are tasty treats. Using planting cages or surrounding bulbs with wire mesh helps protect them. Rabbits enjoy feeding on tulip and lily foliage. A taste repellant can be useful.

What to do with foliage after flowering
After the colorful flush of spring blossoms is over and the flowers are spent, the foliage becomes unsightly as it dies back. Unattractive as it is, resist the urge to remove foliage until it has yellowed, withered, and comes up easily with a gentle tug. It is important to the health of the plant and its flowering. Through photosynthesis, the foliage manufactures nutrients that the bulb will store for the following year.

Strategies to divert attention from yellowing foliage include:

• Interplant colorful blocks of annuals among the bulbs
• Put bulbs behind other plants along the front edge of the border
• Plant taller flowering bulbs behind lower-growing foreground shrubs
• Plant bulbs among groundcovers or perennials, such as hostas and daylilies.

Care, maintenance, and repeat bloom
Daffodils reliably return year after year in Western North Carolina, with some varieties eagerly naturalizing. Crocus, grape hyacinth, lily-of-the-valley, and snowdrops also perform reliably. Many varieties of tulips and hyacinths are treated as annuals in the South as they decline after their first glorious year.

Spring-flowering bulbs need little care after planting. After about 5 years, daffodils can decline, with a decrease in flower size and vigor, and uneven bloom and plant height. You can often prevent this by regularly fertilizing according to a soil test. If your planting becomes too shaded or there is too much competition from other plants, dig the bulbs and relocate them. Dig them after the foliage has died back, but before removing it—otherwise it is easy to forget exactly where they are planted!

Most summer-flowering bulbs need plenty of water while actively growing and well-drained soil. Some bulbs, such as gladioli, lilies, and calla lilies, can overwinter in the soil with a protective layer of mulch, depending on the severity of the winter. Others should be dug up and stored after their foliage has yellowed. Tall, blossom-heavy flowers, such as dahlias and gladioli, may need staking with wire rings or study supports. Drive the stakes in at planting time to avoid damaging the bulbs. Cutting the blooms for indoor use will prolong and encourage more flower growth.

Article written by Sally Wheeler, Extension Master Gardener^SM Volunteer.