Spirea is a fast-growing shrub, and it usually achieves full size within a single growing season. Like many shrubs, this native of China, Korea, and Taiwan is best planted early in the growing season as a container-grown nursery plant, which will allow the shrub’s root system plenty of time to become established before winter. If you must plant in the fall (this sometimes is when nurseries are discounting available stock), try to do it with enough time so the shrub’s roots can settle in and begin growing before winter weather sets in.
Light
This shrub will do best in a spot in your garden that receives full sun; it will tolerate part shade, though with slightly reduced flowering. When planting young bridal wreath spirea shrubs, make sure to provide plenty of room between them: They will grow and can block each other’s light if planted too close together.
Soil
This plant is not picky about the soil it’s planted in, and can thrive in clay, loam, and even acidic soils. Its biggest need is soil that’s well-draining, so the roots never sit in water.
Water
Bridal wreath spirea prefers to grow in well-drained moist soil, though it is able to withstand some periods of drought. Water the plants once a week during the summer whenever rainfall is less than 1 inch. Keep the plants well-watered as they are becoming established—that is to say, for the first full growing season after planting them.
Temperature and Humidity
This plant is quite hardy, surviving both cold winter and hot summer temperatures in its defined range. It thrives in any climate conditions within its USDA hardiness zones (4 to 9). It has no preference for humidity conditions.
Fertilizer
Every spring, add a 2-inch layer of compost over the soil under the shrub. This is usually sufficient to feed the plant, and it will also help to retain moisture and prevent weeds. Additional fertilizing is not necessary, and may even reduce flowering.
Types of Bridal Wreath Spirea
The bridal wreath spirea offered for sale is usually S. prunifolia ‘Plena’. The pure species, as well as a a naturally occurring single-flowered form (Spiraea prunifolia var. simpliciflora) are rarely found for sale. Spiraea prunifolia is a very old landscape specimen, in cultivation since 1864 and regarded by some as inferior to modern cultivars. But it can still be a very dependable and easy-care shrub for more informal landscapes, and it is often seen around farmhouses and rural residences.The common name “bridal wreath” is also sometimes applied to a hybrid shrub, Spiraea x vanhouttei, which is a cross between S. trilobata x S. cantoniensis. This hybrid is very similar to S. prunifolia, but is a somewhat larger specimen, growing as much as 12 feet across, and is hardy to zone 3. It is a very common nursery offering. There are several good cultivars of S. x vanhoutttei, including ‘FiregoldTM’, ‘Gold Fountain’, and ‘Pink Ice.’
Pruning
This plant tends to spread through suckering, so ground suckers will need to be trimmed off if you want to keep the shrubs confined. If desired, the shrubs can be pruned for shape or size immediately after the spring flowering period. Always use clean, sharp pruning shears. A good pruning routine is to remove all dead wood, as well as some of the oldest stems all the way to ground level. This will open up the center of the shrub to sunlight to reinvigorate it. Tips of branches can also be trimmed to control the size of the shrub.
Propagating Bridal Wreath Spirea
The best way to propagate bridal wreath spirea shrubs is by rooting softwood cuttings during the active growing season. To do so: Remember that it is technically illegal to propagate trademarked or patented cultivars. If you are planting a named cultivar, check the plant labels for indications that the plant has been granted or is pending any kind of copyright protection. If so, it should not be propagated in any way.
How to Grow Bridal Wreath Spirea From Seed
Although not common, seed propagation is possible. It’s best to sow the seeds collected from seed clusters in the spent flowers immediately after you collect them. But seedlings will take several years to grow into mature landscape plants, which is the reason why propagation is usually through vegetative means, such as softwood cuttings (see above).
Overwintering
These hardy shrubs generally require no winter protection against cold. Their spiny stems make them fairly resistant to deer browsing, but rabbits sometimes nibble on them when the plants are young, so a protective screen of wire mesh is a good idea for young shrubs.
Common Pests & Plant Diseases
There are no serious pest or disease problems for the bridal wreath spirea, but they can be mildly susceptible to many of the diseases and insects that attack other members of the rose family. These include leaf spot, fire blight, powdery mildew, root rot, aphids, leaf roller, and scale.
How to Get Bridal Wreath Spirea to Bloom
Bridal wreath spirea typically blooms robustly in spring before the stems leaf out. The flowers are small, grouped in clusters of three to six, white with a tinge of green. Flowering is minimal with new shrubs, but after a year you should experience good flowering, provided the shrub is getting plenty of sunlight. This is not a plant that blooms more robustly if you fertilize it. In fact, excessive fertilizer may well lead to fewer flowers. Pruning at the wrong time can also remove the flower buds and cause a temporary loss of flowers. These shrubs bloom on the previous year’s wood, so they should be pruned immediately after they flower. If you prune too late in the fall or in early spring, you likely will be removing the stems containing the buds that will produce spring flowers.
Common Problems With Bridal Wreath Spirea
Bridal wreath spirea is a mostly care-free plant, The chief complaint, mostly among gardeners who haven’t researched the plant before choosing it, is that it can be a somewhat shaggy, unkempt shrub—not the elegant, cascading plant they are expecting from a spirea. If you want that kind of shrub, you are better off planting one of the S. japonica cultivars or hybrids. Bridal wreath spirea is a better choice for large yards where you need an easy-care background shrub that provides a natural, woodsy transition to adjoining property.
