I have a lot of pictures of this plant, and for a good reason. Starting in mid-summer into early fall it is enshrouded in a cloud of deep-blue flowers with a halo of pollinators all around.
It is also known as Blue Mist, Blue Spirea, or Blue Beard. These names are good descriptors given the way the flowers form on spires and have a “fuzzy” texture. This particular variety is even more stunning with a deep, true blue color that is not common in many garden plants. I’m not the only one who appreciates them, as they attract bees, butterflies, and other pollinators to our yard.
*A handy growing summary chart is at the end of the article.*
The foliage is also noteworthy as it has sharply pointed leaves that have a grey-blue tinge to them. The flower buds are the same color, though lighter, before the flowers open so even they add a unique structural component to the landscape. “Dark Knight” is not a plant you will want to bury in the background!It’s color both stands out, yet coordinates so well with a variety of other textures and hues.
Caryopteris also has the added benefit of being somewhat drought tolerant. Some sources say that the plant will not tolerate heavy soil, but that is exactly where it is growing in our yard. However, the soil is allowed to dry out and is not heavily watered so that helps to reduce the water-logging that can happen in heavy clay soils.
It has tolerated our very hot and dry summers (prolonged stretches of 100°+ F) with ease and will tolerate light frosts. Temperatures lower than those found in zone 7 will likely kill off the tissues above ground, but the roots will survive down to zone 5 winter temperatures. Any winter damaged stems can be pruned back.
It’s spread and height is moderate, so it is not a big space hog, but at the same time is large enough to be noticeable and to function as a specimen plant. The plant can be pruned back if needed, without impacting flowering since the flowers are formed on new growth. It is also a deciduous plant, so you will want to keep that in mind when deciding where to place it and what other plants to put near it.
- Height: about 3 feet
- Width: 2-3 feet
- Sun: full sun, can tolerate a little shade
- Water: somewhat drought tolerant, does not tolerate soggy soil
- Soil pH: neutral to slightly acidic
- Soil type: amend heavy clay or loose sandy soil
- Key nutrients: fertilize as you would for other flowers
- Planting time: best to plant before summer heat to allow it to get established