Caryopteris is not a Spiraea

It is unfortunate that Caryopteris has the common name of Blue Spirea 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 Roseaceae family while Caryopteris is in the Verbenaceae family.

The genus Caryopteris is comprised of roughly 15 species, most being native to Asia. Only are few of these species are grown in North America as ornamentals. The majority of the ornamental selections sold here are hybrids; Caryopteris x cladonensis (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 here after 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 die-back 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 its flower buds (and flowers) are formed on new wood so 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 of 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.

Caryoteris 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 turn off to deer so it rarely bothered by Bambi and her four legged friends.

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 and 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’ which can look a bit ratty by mid summer.
Lil' Miss Sunshine ('Janice') is new variety that I hybridized using Petit Bleu and Sunshine Blue. This plant has be best attributes of both parents as it is hardy, 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’ 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


  1. Anonymous5:46 PM

    My five Sunshine Blue are a beautiful plant.
    BUT....bee careful where you plant it since the honey bees have a picnic on the plant.

  2. How are the yellow foliage and variegated ones in keeping their interesting foliage through the summer?

  3. Bees do like these plants when they are in flower but they are so busy collecting pollen that they should not bother anyone.

    As far as the folaige on the variegated plants, I can say as I've not grown them myself. I've only seen the plants.

  4. I like the sound of dark foliage on Petit Bleu. The yellowish caryopteris around my neighborhood look too much like the chlorotic rhododendrons around here. I can't get past the idea that they're sick, so I never enjoy seeing them. But maybe a dark-green-leaved cultivar would seem pretty to me!

  5. Anonymous2:03 PM

    I live in Zone 4 and planted a Sunshine Blue last year. It currently has no leaves and doesn't look to be doing anything. Is it dead or is it possible that it may still grow? Shouldn't it at least have leaves by now?

  6. Caryopteris is a plant that is very late to break bud in the spring so it might be alive. You should note that Caryopteris is rate at a zone 5 so it may be that your plants did not survive. Time will tell.

  7. Two years ago, I planted two Petit Bleu on the south side of the house in what seems an ideal location. They did great last year, with plenty of blooms and healthy foliage, but this year, the leaves have been turning orange and dropping, with die-off spreading from the center of the shrubs outward. I live in Cincinnati, which is on the Zone 6/7 border. Any ideas? I love this plant and want to save it.

  8. Anonymous1:06 PM

    I have a lovely group of three caryopteris that are staggered and thriving under a row of pine trees. I would like to place a group of three companion plants with them for color...Does anyone have any suggestions? I love the airy appearance.


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