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Autumn clematis, how sweet it is

By By Steve Strong / area horticulture extension agent
Aug. 20, 2003
Plant lovers out for a stroll or a lazy drive with the windows down can catch a whiff and a glimpse of one of Mississippi's best native wildflowers for late summer color.
Sweet autumn clematis covers roadside privet hedges and fences with cascades of billowy white blooms from now through September. It's a semi-evergreen climbing vine that thrives in moist thickets and neglected areas.
Clematis paniculata, or sweet autumn clematis, is one of the 200 species of related herbs and trailing woody vines found throughout the temperate regions of the Southeast. It is easily identified by its masses of small, white, star-shaped flowers that emit a pleasant, sweet fragrance, with compound leaves arranged opposite on the stem with three leaflets each.
Not to be confused with poison ivy, which has toothier leaflets, this type of clematis can be found naturally climbing over the tops of larger shrubs and along creek banks. Moist woods offer the same type of habitat for two of sweet autumn's cousins, Clematis crispa, (swamp leather-flower, small blue bell shaped blooms), and Clematis glaucophylla (pink bloomed small leather-flower).
Sweet autumn is one of the most vigorous of the native clematis vines, and may be too invasive for some gardeners. This plant wants a lot of room to grow, and like other clematis species, seems to prefer full sunlight while having its roots cooled by the shade of other shrubs nearby.
The flowers are particularly attractive to honeybees that swarm the vines in late summer when other pollen-producing plants become scarce. There are conflicting reports about whether clematis pollen causes an off-flavor in homegrown honey, but another attractive feature of sweet autumn is the silvery-plumed seed clusters that resemble spent dandelion blooms.
The hybrid clematis vines that most gardeners train around mailboxes and lampposts are actually native to Asia and the Himalayas, and are a little more challenging to grow. The larger flowering hybrid types are adapted to much cooler weather, and one tip for success is using a good amount of mulch to help shade the roots (or let the vine grow inside of an evergreen shrub).
A second key to success for the hybrids is keeping the soil pH near neutral, around 6.5 to 8.0. Most soils in East Mississippi are somewhat acidic and require periodic applications of lime to maintain the optimum soil pH to grow clematis.
Soil testing through Mississippi State University is just $6 per pint size sample, and fall is a perfect time for soil analysis.
Unlike the hybrids, Sweet Autumn clematis is rarely found in local garden centers since it is more of a roadside weed that can be easily propagated by seeds and cuttings.
The seeds persist on the vine for several months and can be collected any time in the fall, with refrigeration for three to four months recommended to increase germination. Sowing indoors will speed up the growth cycle, but new plants may take two years or longer to flower.
For more information on Mississippi wildflowers or other gardening information, contact the county Extension office at (601) 482-9764, or me directly at steves@ext.msstate.edu.
Also go to the Mississippi State University Web site at www.msucares.com for additional articles on hot new plants and upcoming gardening events.

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