We’ve written about the most popular plant groups for the Bay Area: California natives, dahlias, irises, roses and succulents. In today’s column, we focus on tulips, which are popular in many parts of the nation but infrequently seen in our gardens.
Tulips are members of the genus tulipa, which is one of 15 genera in the lily plant family (liliaceae). The genus includes some 75 species that are native within a wide area ranging from Southern Europe through the Middle East and Central Asia.
Tulips are widely cultivated, and a broad variety of colors, forms and bloom periods are available. There are 15 divisions of tulips based on flower morphology and plant size. These divisions also are listed within three categories to their flowering season: early, mid and late.
Despite the impressive diversity of today’s tulip cultivars, local gardeners generally do not grow these plants because much of the Bay Area lacks the chill period that most tulips require during their dormancy.
The large majority of tulip bulbs that are available from mail-order nurseries or local garden centers are recommended for planting in USDA Zone 8 or lower. The Monterey Bay, for exampled, is in Zone 9, which does have cool and even freezing temperatures but does not provide the 12 to 14 weeks of cold soil (temperatures below 55 degrees) that tulips require in order to bloom during the following spring.
It is possible to get lucky with a tulip variety that adapts to the local climate. I have had regular blooms from Tulipa ‘Peer Gynt’, purchased in 1998 during a visit to Keukenhof Gardens in the Netherlands. It has bloomed every year since then, without special care on my part. Evidently, all tulips do not require the same chill treatment.
But all is not lost! You can grow tulips in a temperature climate by using an appropriate strategy. Here are approaches to consider:
Pre-chilled tulip bulbs
Some online nurseries and possibly local garden centers offer tulip bulbs that have been pre-chilled and delivered in time for planting. For example, browse to www.tulipworld.com and search for “pre-chilled.” As the season advances, more temperate-climate gardeners and cold-climate procrastinators will want to grow tulips and more nurseries will offer pre-chilled bulbs.
DIY bulb-chilling
You could order tulip bulbs early enough for you to chill them below 55 degrees before planting in late November or mid-December. Some online recommendations call for a chill period of as short as four weeks, but the optimal duration is 12 weeks, reflecting the natural period for tulips. The bulbs should be refrigerated in a paper bag, and located away from fruits or vegetables, which emit ethylene gas that can kill the tiny flower inside the bulb.
This approach calls for ordering your bulbs soon. Most mail-order nurseries prepare to ship tulip bulbs on a schedule that is appropriate for areas with the required natural chill period, so place early orders by phone to confirm that you need the bulbs in time for an artificial chill period.
Tulips should be planted in November in most parts of the country. This schedule allows the bulbs to come out of summer dormancy and develop roots before the ground freezes and then burst into bloom when warm weather arrives in late March or early April.
It’s acceptable to plant the bulbs in the late fall in the Bay Area, anticipating that the ground is unlikely to become frozen during the winter, and will not become warm enough to stimulate premature sprouting.
Whether you plant pre-chilled bulbs or chill them yourself, plan to lift the bulbs after the foliage has ripened (usually around mid-May), store them in a cool dry place during the summer, and provide a chill period again before replanting in the late fall.
Purchase Temperate-zone Species Tulips. As indicated above, there are many species of tulips, some of which are native to climates similar to that of the temperate Bay Area. These species are attractive in their own right, although perhaps not as showy as the most recent crop of cultivars.
Species to search for online include Tulipa clusiana (several named varieties can be found), T. saxatilis, and T. urumiensis. These species are listed for Zone 9 and could be just planted in the fall, but providing the usual chill period might provide optimal blooms.
Advance your gardening knowledge
Preparing today’s column brought me to several tulip-related websites of particular interest. To learn more about the genus tulipa, check out these sites.
For brief descriptions of the 15 divisions of the genus tulipa, browse Wikipedia.com. Search for tulips, and scroll down to “Horticultural classification.”
For an overview of tulip cultivation, visit brecks.com/category/Tulip_Flower_Bulbs
For a discussion of tulips’ chilling needs, visit https://amsterdamtulipmuseumonline.com and search for “cold period.”
For virtual visits to the spectacular Keukenhof garden, visit Keukenhof.nl. Numerous short videos are available online by searching for “Keukemnhof” and clicking on “video.” An interesting presentation is “How 7 Million Flowers Are Planted At Keukenhof Every Year,” available on YouTube.
For images of a sampling of the thousands of cultivars of the genus tulipa, visit commons.wikimedia.org/wiki/Tulipa_cultivars.
For images of species of the genus Tulipa, visit commons.wikimedia.org/wiki/Tulipa.
Finally, for a virtual tour of species tulips, visit www.tulipsinthewild and click on “slideshow.”
Enjoy tulips in your garden!
Tom Karwin is past president of Friends of the UC Santa Cruz Arboretum and the Monterey Bay Iris Society, a Lifetime Member of the Monterey Bay Area Cactus & Succulent Society, and a Lifetime UC Master Gardener.
Source: www.mercurynews.com