Crop Rotation Group
Miscellaneous
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Soil
Fertile, well-drained soil enriched with compost or other organic matter, with a slightly acidic pH.
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Position
Full sun to partial afternoon shade.
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Frost tolerant
Spireas are hardy deciduous shrubs, tolerating winter temperatures to -35°F (-37°C).
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Feeding
Boosting soil fertility results in bigger, better spirea flower clusters. Topdress the root zone with rotted manure topped by an organic mulch in early spring. Or, apply a balanced organic fertilizer twice yearly, once in spring and again in early summer.
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Companions
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Spacing
Single Plants: 4' 11" (1.50m) each way (minimum)
Rows: 4' 11" (1.50m) with 4' 11" (1.50m) row gap (minimum)
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Sow and Plant
Set out purchased plants in spring at about the time of your last frost. Container-grown plants can be set out until early summer. Enrich the planting hole with good compost and a balanced organic fertilizer, following label directions on how much to use. Water regularly after planting, and cover the root zone with an organic mulch to keep the soil moist at all times through the first growing season. Spacing varies with the type grown, but spiraeas usually need to be spaced at least 5 feet (1.5 m) apart.. Bridal wreath spirea are often grown as single specimen plants. Check plant tags for a plant’s mature width when planting spireas in combination with other shrubs. Many new dwarf spireas can be grown in 14-inch (35 cm) pots.
Our Garden Planning Tool can produce a personalized calendar of when to sow, plant and harvest for your area.
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Notes
Spireas are generally divided into two types: bridal wreath spirea and Japanese spirea. Bridal wreath spirea grows into a symmetrical, fountain-shaped shrub that becomes covered with small white flowers in spring. An instant focal point in the spring landscape, bridal wreath spirea is valued for its flowers and its graceful form. Japanese spirea (S. japonica hybrids) are more compact plants that produce airy clusters of pink to red flowers in early summer, and some cultivars continue blooming through the summer. Leaf color is also remarkable, ranging from red to chartreuse. Older varieties of Japanese spirea became invasive in some parts of the US and Europe, but the introduction of seed-sterile cultivars such as ‘Neon Flash’ has solved this problem. The need to prune varies with cultivar. Prune bridal wreath spirea in early summer by cutting out old branches close to the base of the plant. Japanese spirea can be pruned in fall or early spring to remove dead branches and keep the plants neat. Japanese spirea blooms on new wood.
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Harvesting
All spireas make good material for cut flower arrangements. The airy flower heads of Japanese spirea can hung in small bunches to dry.
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Troubleshooting
As members of the rose family, spirea may occasionally show leaf spots and leaf damage due to moth larvae, but they are seldom subject to serious damage. Spireas are of little interest to deer.
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