Photo by William Hanley.
Magical and more than a little mysterious, Duke Gardens’ annual spring bulb displays in the Historic Gardens and Doris Duke Center Gardens are a source of fascination for both frequent visitors and newcomers alike. Over the years, the Gardens’ hardworking horticulturists have fielded many questions about these bulbs during what is consistently the most popular and well-known of the Gardens’ many dramatic vistas.
The ideal time for planting depends on the bulb in question. Many spring-blooming bulbs, such as tulips, require a certain amount of cold weather in order to bloom and are best planted in early to mid-fall in our region. However, as North Carolina has relatively short and milder winters, it is often difficult for fall-planted bulbs to rack up enough “chilling hours.” One way around this is to buy pre-chilled bulbs or to chill them for the appropriate time prior to planting. Another is to focus on bulbs with relatively low chill requirements, which are more likely to bloom reliably regardless of the weather—and may even take advantage of the warmer spells by blooming early.
As bulbs are most effective when planted en masse, advance planning is ideal to ensure harmonious results. Bulbs must be planted so that their developing stems are upright and situated at the correct depth in the soil for their size. Depending on the area in question, bulbs can be planted by hand with a trowel or a bulb planter, or even a small shovel. Because spring-blooming bulbs bloom before the trees leaf out, they can be planted beneath the existing canopy as long as the roots are avoided, or they can be planted in sunny open fields or dedicated garden beds.
Here at Duke Gardens, the tulip bulb display is treated as an annual planting, which means they are dug up and composted at the end of the blooming season to make room for summer flowers. Given the unreliable number of chilling hours each winter, high levels of summer humidity, disease, and predation by deer, voles and squirrels, tulips rarely survive a full year outdoors here without extensive protections. The best way to ensure a beautiful display is to start from scratch each fall with fresh stock purchased from commercial growers in the Netherlands.
Home gardeners who dream of beautiful bulb displays of their own but prefer not to dig up their gardens every fall to continually replant have a number of options available to them. They can focus on cold-hardy species that naturalize well in our area, such as daffodils and narcissus, whose leaves are laced with bitter toxins to ward off predators and come in a wide variety of shapes and colors. Careful cultivar selection is essential, with the North Carolina State Extension regularly trialing varieties for their performance in our climate. Gardeners can also experiment with “forcing” potted bulbs to bloom early indoors, where they are protected from the elements and make for beautiful gifts and centerpieces to brighten the winter doldrums—enjoyable not only in their own right but as a welcome stepping-stone on the road to spring.
One of the most frequently asked visitor questions during bulb season is, “When is the best time to see them?” The answer is always, “Whenever you’re here!” Strategic interplanting of early, mid-season and late-blooming varieties of tulips, along with a diverse mixture of other species, allows the “peak” to stretch from March through early May. As a result, there is always something in flower to catch and intrigue the eye for the duration of the season, with each day offering up a slightly different perspective than the day before.