Spiraea

( spy - REE - uh )

At-A-Glance Information

This genus of flowering deciduous shrubs, commonly called Spirea, Meadowsweet, or Steeplebush, needs full sun to light shade and moderate to regular water. These shrubs are native to the temperate area of the Northern Hemisphere, with the most naturally occurring species found in eastern Asia. There are two distinct types of Spiraea, those in the 'Bridal Wreath' category have white flowers and bloom in spring to early summer, and the 'Shrubby' category of Spiraea blooms from summer through fall in a range of colors from pink to red to white. The flowers on these shrubs will attract butterflies to your garden.

Spiraea Species and Varietals

The genus Spiraea is in the plant family Rosaceae, and includes between 80 and 100 species (including many beautiful hybrids). Previously, the genus included plants in the genera Filipendula and Aruncus, though they have now been separated. There are many plants whose common names include 'False Spiraea'; these are plants that look similar and can be used in many of the same ways in the garden, but are not true Spiraea species. Spirea growing zones vary depending on the species. For more information, review the descriptions below. To find your zone, click here: Zone Map.

Spiraea cantoniensis 'Flore Pleno' (Double Bridal Wreath)
This species is native to China and Japan and grows well in zones 3-11 and 14-23, reaching 5-6 feet tall and 10 feet wide. Branches have an arching habit and double flowers bloom in late spring to early summer Leaves are blue-green, and this plant is nearly evergreen in milder climates.

Spiraea densiflora (Mountain Spirea)
This species grows well in zones 1-9 and 14-21, native to the Sierra Nevadas up to British Columbia. The leaves are wooly white underneath, green on top, and turn yellow in autumn. Flowers bloom in summertime in a rose-pink color. Variety 'Summer Song' reaches 2.5 feet tall and just as wide, with bronze new growth and fall color.

Spiraea douglasii (Western Spirea)
Best in zones 1-9 and 14-24, native to the Coastal Ranges in Northern California up to British Columbia and east to the Rocky Mountains. It reaches 3-6 feet tall and just as wide. It can be invasive; it will spread via suckers. Leaves are dark green on top and velvety and white underneath. Flowers are pale to deep purple-pink and blossom at branch tips in summertime. This species prefers acidic soil and needs ample water. Great for wild plantings near streams or rivers. 
Spiraea japonica
This species grows well in zones A2, A3, 2-10 and 14-21, and is native to Japan and China. It has an upright, shrubby habit and produces clusters of pink flowers above bright green foliage. The varieties of this species are more widely known and grown in gardens; they are listed and described here.
Spiraea x bumalda
Reaches 3 feet tall and wide, with dark pink flowers and bronzey new foliage.
'Anthony Waterer'
3-5 feet tall, with carmine-pink flowers and reddish-purple new growth that matures to a vivid green.
'Goldflame'
2.5 feet tall and just as wide, with pink flowers and bronzey new foliage that matures to chartreuse, and turns red-orange in autumn.
'Little Princess'
To 3 feet tall and 6 feet wide, this variety has rose-pink flowers.
'Magic Carpet'
This variety reaches 1.5-2.5 feet tall and a little wider, with pink flowers and new foliage in bronze which matures to chartreuse and yellow.

Spiraea nipponica 'Snowmound'
This variety grows ell in zones 1-11 and 14-21, and is native to Japan. It is a Bridal Wreath type of Spirea that reaches 2-3 feet tall and 3-5 feet wide, with a profuse bloom of white flowers in late spring to early summertime. Leaves are dark green.

​Spiraea prunifolia 'Plena' (Bridal Wreath Spirea, Shoe Button Spirea)
This species grows well in zones A2, A3, 2-11 and 14-21. It is native to China and Taiwan, and has graceful, arching branches. It reaches 6-7 feet tall and wide. Flowers are double and white, and leaves are dark green and turn colors in fall.

Spiraea thunbergii
This species is native to China and Japan, and grows well in zones 1-11 and 14-21. It is a Bridal Wreath species that reaches 3-6 feet or more, and produces round clusters of white flowers along branches in early spring, before leaf-out. Leaves are blue-green and turn red-brown in fall. Variety 'Ogon' has yellow-green leaves.

Spiraea trilobata 'Swan Lake'
This variety is native to Siberia and northern areas in China, and grows well in zones 1-11 and 14-17. It reaches 3-4 feet tall and produces many tiny white flowers in springtime. Variety 'Fairy Queen' is a more compact plant reaching just 3 feet tall.

​Spiraea vanhouttei
Best in zones A1-A3, 1-11 and 14-21, and is the quintessential Bridal Wreath variety of Spirea. Branches have an arching habit, and leaves are dark green, turning purple in autumn. Flowers form in clusters of white from the middle of spring to late spring, and will continue into early summertime if temperatures do not get too high. Variety 'Renaissance' is powdery mildew and rust resistant. 'Pink Ice' has leaves variegated with white.

Caring for and pruning spiraea shrubs

Spirea are relatively easy to grow, and are not fussy about soil. Plant your Spirea in full sun to partial shade. Most species in this genus do well with at least six hours of sunlight per day; this exposure will ensure optimal growth and flowering. These shrubs, although not too picky about their soil conditions, do prefer soil to be well-draining with a slightly acidic to neutral pH (between 6.0 and 7.0). Water new plants regularly to help establish a strong root system. Once mature, Spirea shrubs are generally drought-tolerant, but do benefit from regular waterings during drier periods of the year. Ensure that soil is draining well; waterlogged roots can cause many issues. Apply a layer of organic mulch around the base of these shrubs after planting to retain soil moisture and regulate soil temperature, as well as to suppress weed growth. Fertilizing is not needed.

Prune Bridal Wreath types after flowers have faded, and cut the flowering wood down to the ground. For Shrubby Spireas, prune in late winter or early spring before new growth begins to show. Remove spent flower clusters to encourage repeat blooms. These shrubs generally respond well to pruning after the flowering period has ended. As with many other plants, removal of dead, diseased, damaged, and crossing branches is a good rule of thumb. 

Propagation

Spirea can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Spiraea shrub, follow the instructions below:

Propagating Spiraea by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Spiraea by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a paper towel, a sealable plastic bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
  2. Harvest your seeds. The seed pods will dry out, turn brown and begin to open when the seeds are ready to be harvested. Once they have dried out and begun to split open, cut them off the plant and place them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Place the seeds on a damp paper towel, roll the towel up, and place it in a sealable plastic bag. Place the bag in your refrigerator and leave it in there for between 90 and 140 days. Then, move it to an area that stays light and at a temperature of between 65 and 70 degrees Fahrenheit. Seeds should sprout within a few days
  4. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light and stays around 70 degrees Fahrenheit.. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes a couple of days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  5. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
The seed heads on Spirea plants are left behind after flowers have faded.
Spiraea seeds.

Problems and Pests

Although Spiraea plants are generally resistant to pests and diseases, they can have some issues with the following common garden pests:
  • Spider Mites
  • Aphids
For information on dealing with these issues, see the following links:
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Gallery

Use Spiraea shrubs to line walkways and steps.
The graceful, drooping branches showcase profuse blooms.
These shrubs come in a variety of foliage and flower colors; there is really a Spirea for every landscape.
Dwarf Spirea forms are wonderful for edging lawns and fronting mixed beds.
Flowers on these shrubs bloom profusely in spring, summer, or fall, depending on the type chosen.
There are many plants known commonly as 'False Spirea', including Astilbe and Sorbaria (pictured).

Videos

An informational video about these gorgeous ornamentals.
How to prune your Spiraea shrub.
Caring for Japanese Spirea shrubs.
An introduction to the Spirea genus.

Resources

How to Plant and Grow Spirea
Spirea: Plant, Grow and Care for Spiraea Bushes
How to Grow and Care for Spiraea Shrubs
Wikipedia: Spiraea
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 610 - 611, Spiraea
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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