INTRODUCTION to TIM WOOD, this week’s guest writer.
Tim is a third Generation Plantsman who got his formal training at Michigan State University, the Arnold Arboretum at Harvard and the Chicago Botanic Garden, with a few other stops along the way. Tim has worked for several nurseries, and is currently the New Products Manager at Spring Meadow Nursery, Inc. in Grand Haven, Michigan. He has discovered plant ‘stars’ such as Wine & Roses® weigela and ‘Limelight’ hydrangea and brought them to the North American market. He also has his own plant-breeding program at Spring Meadow, and has recently introduced Incrediball™ hydrangea and Bloomerang® reblooming lilac. Tim was named Michigan Nurseryman of the Year is in the International Plant Propagators Society and the Garden Writers Association, among others. You can keep up with his international horticultural adventures on his popular blog, The Plant Hunter.
It is unfortunate that Caryopteris has the common name of Blue Spiraea for it is not a Spiraea and it’s just plain confusing. How this came about, I do not know as they are not even in the same family; Spiraea is in the Rosaceae family while Caryopteris is in the Verbenaceae family.
The genus Caryopteris is comprised of roughly 15 species, most being native to Asia. Only a few of these species are grown in North America as ornamentals. The majority of the ornamental selections sold here are hybrids; Caryopteris x clandonensis (pronounced Cary-op-ter-is clan-don-en-sis) which is a hybrid between Caryopteris incana and Caryopteris mongholica. Unless otherwise noted, the following information hereafter refers to this hybrid.
Caryopteris is a fall flowering shrub with rich blue to purple-blue flowers. While it is hardy to USDA zone 5, it is typically a dieback shrub in the North, behaving much like a Buddleia. While the plant makes woody stems, they are tender and die back during the winter. As the plant grows back quickly in the spring and since its flower buds (and flowers) are formed on new wood, the plant does not miss a beat.
Culturally there are three things necessary to grow a nice plant. First off, it loves full sun. It will grow in partial shade but it will not look happy or flower nearly half as well as a plant in full sun. In addition, the yellow leafed cultivars have much better color in full sun. In partial shade, the leaves will appear a dull, washed out green.
The next thing to know is that Caryopteris needs well-drained soil. It will not tolerate heavy, wet clay soils, or at least not for long. People often blame the plant for not being winter hardy because their plant did not make it through the winter, but the real culprit is wet soil. Well-drained soil is a must. Once established, Caryopteris is very drought tolerant and requires even less water.
My final bit of cultural advice deals with pruning – as the plant typically dies back in the winter, you should only have to prune the plant once, and that is in the spring after the plant starts to grow. Simply cut the plant back to wood with active sprouts. If you wish, you can give the plant a slight shearing in early summer to bulk up the body of the plant. Fall pruning is not recommended, as it stimulates the plant to grow when it should be going dormant - the result can be a dead plant the following spring.
Caryopteris is a wonderful garden plant because it offers a mass of colorful blue flowers in late summer when few other plants are blooming. It’s a great source of pollen for bees and butterflies. Its aromatic foliage is a turn off to deer so Bambi and her four legged friends rarely bother it.
There has been a flurry of Caryopteris breeding over the past 15 years and we have never had such wonderful plants for the garden. Here are a few of the newest cultivars to hit the market.
Petit Bleu (‘Minbleu’) is one of my favorites as it is a semi-dwarf plant with very tight branching and a nice mounded habit. The flower color is a very dark blue; the foliage is very dark and glossy, which makes a great background for the flowers.
Sunshine Blue(‘Jason’) is a yellow leafed form of Caryopteris incana. It is a larger plant than most (3-4’) with masses of clear blue flowers that appear a bit earlier than other varieties. This English selection has very good hardiness and is more adaptable to heavier soils. It was a vast improvement over ‘Worcester Gold’ that can look a bit ratty by midsummer.
Lil' Miss Sunshine ('Janice') is new variety that I hybridized using Petit Bleu and Sunshine Blue. This plant has the best attributes of both parents, as it is hardy and compact with glossy bright yellow foliage. The abundant flowers are a rich clear blue. It should be available in summer of 2010.
‘Sterling Silver’ is a new selection from the renowned English plantsman Peter Catt. It is a silver leafed selection that will most certainly replace 'Longwood Blue' once it is more widely available.
There has been a rash of variegated forms released in the last few years. Two of the better looking plants are ‘Summer Sorbet’ which has green and yellow leaves, and ‘White Surprise’ which has silvery-green leaves adorned with a thin cream margin of variegation. As with most variegated plants, these will throw the occasional non-variegated shoot. Simply prune and remove these shoots as they appear.
Proven Winners® ColorChoice® flowering shrubs are developed by Spring Meadow Nursery, Inc. in Grand Haven, Michigan to help consumers be more successful with gardening. Go to www.springmeadownursery.com or www.provenwinners.com for more information.
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