Snowmound SpireaSpiraea nipponica ‘Snowmound’
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Spiraea nipponica ‘Snowmound’
Outdoor Growing zone
Full Sun, Partial Sun
The Snowmound Spirea is a spectacular flowering shrub for late spring, covered in pure-white blooms in May or June. Each arching branch is garlanded from top to bottom with domes of small white blossoms, making a beautiful sight. This mounding plant will grow 3 or 4 feet tall and wide, and a little larger under ideal conditions. The small leaves are an attractive very dark green, with bluish tones on the underside. They turn yellow in fall. Grow this beautiful plant among other flowering shrubs for an all-season blooming border or grow it as an informal hedge. Use it on banks and among boulders, or in containers and planter boxes.
Full sun will give you the best results with the Snowmound Spirea, although it will enjoy a little afternoon shade when grown in the hottest zones. It grows in most well-drained soils, including clays, and does best in richer soils with a regular supply of moisture. Established plants have some drought resistance, and they are normally never bothered by pests, diseases or deer. For the best blooming, prune strongly in summer, soon after the blooms have faded.
In many old gardens you will see a big arching shrub with white flowers in late spring. This is the old-fashioned ‘bridal wreath’ spirea, which only looks good with complex pruning, and grows way too big for most gardens, crowding out other plants. It has a much more well-behaved relative – the Snowmound Spirea – that has similar blooms, puts on a spectacular show, but stays compact and mounding, with shorter arching stems that give it a great look. Usually about 4 feet tall and wide, its profuse spring show of snowy white blossoms is a guaranteed stand-out display, and this tough and reliable plant is the ideal way to fill shrub beds with spring color from a shrub that stays neat, so that your summer shrubs can have their space as well.
The Snowmound Spirea is a mounding shrub that typically grows 3 or 4 feet tall, but its size varies a little depending on soil conditions and pruning, and it can often reach 5 feet. It spreads to at least the same width, and sometimes a little more, with a dense and bushy structure made up of many upright but arching branches. The leaves are a little over one inch long, elliptical, with small serrations along the edges, mostly towards the pointed tip of the leaf. They are dark green, and the undersides are lighter green, with a bluish tone. In fall the leaves turn yellow, and the winter stems are dark reddish-brown, with a slight sheen to them.
In May or June, along with the new leaves, clusters of flower buds appear all along the stems. These open to snowy white, completely smothering the bush in bloom for several weeks. The dome-shaped clusters stand on the upper sides of the branches, making it look exactly like there has been a heavy snowfall. The individual flowers are tiny, with five spreading petals, but there are dozens in each cluster, and the effect is both charming and eye-catching. Following flowering the blooms turn into small brown seed pods of no particular beauty, but they are inconspicuous, and they are soon hidden by the many new leafy stems that rise from within the bush. Those new stems will carry the flowers next spring.
This shrub is an ideal medium-sized bush for the middle of larger beds, or the back of small ones. It can be grown in a bed by itself, as well as mixed with other shrubs. Make a bed of constant blooms by mixing it with summer-flowering, and fall-flowering shrubs. Use it as an accent in a smaller space, on slopes, or among rocks and boulders. It also makes a great container plant for pots and planters, and a wonderful informal hedge, spacing plants 3 feet apart.
The Snowmound Spirea grows well from zone 4 to 8, and in sheltered spots in zone 3 as well. It is tough and reliable, taking both cold and heat.
The Snowmound Spirea grows best in full sun, but in warmer zones it will also grow well with a little afternoon shade. It grows best in richer, well-drained soil, but it will do well in poorer soils too, and it tolerates normal periods of summer dryness. It will grow well in heavy clay soils, if they are not constantly wet.
The Snowmound Spirea is an easy shrub to grow, and it can be grown with minimal care and maintenance. Because it relies on new growth for the next year’s blooms, some watering during dry spells, and some fertilizer in late spring will give the best results. It normally has no pests or diseases, and deer don’t usually bother with it.
For the best results some attention after flowering is very worthwhile. You can simply trim it back to remove the old flowering stems, but more careful hand pruning will be rewarded with a more graceful form and more profuse blooming. Wait until you see new stems starting to grow, and then cut all the old stems that have flowered back to where new shoots are growing. It will look a little bare for a short time, but don’t worry, it will soon fill out again with lots of new growth. Don’t trim the new stems at all, as the beautiful arching look depends on them growing to their full length. A short time spent pruning will be amply rewarded with a wonderful spring display. Don’t be afraid to prune hard, because older stems won’t flower at all, and this vigorous shrub can easily take hard annual pruning, removing all the branches that have flowered.
Spiraea nipponica is a shrub that grows naturally only on the island of Shikoku, Japan. The name ‘nipponica’ means from Japan, but this is not the Japanese spirea, which is Spiraea japonica. Philipp Franz von Siebold was a German physician and botanist who lived in Japan from 1823 to 1830, as the doctor to a Dutch trading post. He studied and collected many plants native to Japan, and he brought many to Holland, creating a collection that established that country as a center for horticulture. Among them was Spiraea nipponica, which he also grew in his private gardens in Leiden, Germany. It was not widely offered for sale until 1882, and it was first grown by the French nursery of Lemoine, famous for their lilacs. We don’t know exactly where the variety called ‘Snowmound’ came from, but it seems to have originated in America, perhaps as early as 1908. It is a more compact form of the parent shrub, with slightly narrower leaves, and very profuse blooming.
The Snowmound Spirea received the Award of Garden Merit in 1982 from England’s Royal Horticultural Society – a recognition of its value and beauty. It is one of the most beautiful flowering shrubs for late spring available, and small enough to find a home in every garden. Order now, because this plant disappears from our farm faster than the melting snow in spring.