Winter chilling is crucial to most temperate climate fruit and nut trees, ornamental shrubs, perennial plants, and native seeds. These plants require a prolonged period of cold, aka chilling, to break dormancy and bloom in spring. One model used to calculate chill hours for South Carolina plants counts the number of hours when the air temperature is between 32°F and 45°F.
You’ve observed forsythia, Japanese apricot, cherry, plum, and saucer magnolia in bloom already. The leaf and flower buds of plants log the chill hours and when the requisite hours are met, e.g., 600 for the saucer magnolia, the buds open. Saucer magnolia is considered a low chill plant. Fig, pomegranate, quince, and persimmon require 300 or less chill hours in order to bloom and set fruit.
Knowing the typical chill hour accumulation of your geographic region is the primary standard to use in selecting cultivars of lilac for your garden. Lilacs are reputed to be a northern heirloom plant thriving best in USDA hardiness zones 4-7 gardens. The common or French lilac, Syringa vulgaris, a 17th century colonist introduction from Europe, requires long cold periods to trigger flowering and is not tolerant of Zone 8’s extended hot and humid climate or the highly acidic soil. Lilacs like a soil pH of 6.5-7.
Lilac ‘Baby Kim’ is the smallest lilac at two feet by two feet. Its purple flowers attract butterflies.
The good news is breeders have introduced low chill cultivars for Zone 8 while maintaining the luxurious lilac fragrances and adding qualities like compact size and reblooming in fall. Request these lilacs at your local garden center:
• Little Darling ® Lilac—This fragrant lilac (4 feet tall x 4 feet wide) blooms twice a year! Large clusters of dark-purple buds open to classic lilachue flowers in spring, with a second, lighter bloom set in fall. This compact lilac (4’ high x 4’ wide) with a rounded shape is perfect for containers and mixed borders.
•Syringa pubescens patula (Syringa patula) ‘Miss Kim’—Korean lilac is slow-growing reaching six to eight feet tall and wide. The late flowering lilac with purple buds open to very fragrant, lavender-blue blossoms that attract butterflies and hummingbirds. ‘Miss Kim’ gives three-season interest with burgundy-tinged leaves in fall.
Scentara ‘Double Blue’ has large clusters of highly perfumed, lavendar-blue, double flowers.
• Baby Kim ® — the smallest lilac, growing only two to three feet high and three feet wide. Shiny green leaves attractively feature the non-fading, purple flowers that attract butterflies.
•SCENTARA® lilacs (Syringa x hyacinthiflora)— a dwarf series ideal for warm climates to Zone 8 with the best fragrance from their parentage along with good resistance to powdery mildew. Scentara Pura® grows four to six feet tall and wide, bearing deeply scented, pure purple flowers. Scentara® Double Blue grows 6 to 8 feet tall and wide and is a sensational bloomer with large clusters of highly perfumed, lavender-blue, double flowers.
•Sugar Plum Fairy® (Syringa vulgaris)—reaching four feet tall and five feet wide is a late bloomer bearing spicy scented clusters of rosy pink flowers attracting butterflies and hummingbirds. References
Lilac ‘Little Darling’ is a compact reblooming lilac for containers and mixed borders.
Payero, J. and Sekaran, U. (2021) County Specific Chill Hours Accumulation in South Carolina. Atmospheric and Climate Sciences, 11, 508-519. doi: 10.4236/acs.2021.113030.
National Garden Bureau. ngb.org/year-of-the-lilac/
Researchers at Clemson University Edisto Research and Education Center provide this current graph of long-term average of total chill hours by county in South Carolina.
Loading Comments