In autumn, the summer spar first turns its foliage a deep reddish brown before it sheds its leaves. But even in winter, the shrub contributes to the beautification of the garden due to its dense growth. The filigree red-brown twigs are particularly attractive when fine ice crystals form on them or a thin layer of snow remains on them. In spring, the leaves appear in shades of reddish before turning their true green or yellow color. Spiraea japonica is a very undemanding plant that is particularly in demand among gardeners.
Table of Contents
- botanischer Name: Spiraea japonica
- other names: Japanese Spiraea, Japanese Spiraea
- belong to the rose family
- deciduous (shedding foliage)
- perennial small shrub or dwarf shrub
- leaves: lanceolate, deeply serrated
- Flower: white, pink, crimson
- Flowering period: May to October
- Use: solitary or ornamental hedge, ground cover, planting on slopes
species and occurrence
The summer spar originally came from Asia, hence its botanical name Spiraea japonica. A total of around 80 different types of spars are known worldwide, eight of which are also native to Europe. Around 30 different cultivated forms of summer spiers are commercially available. These include above all the dwarf varieties that reach a maximum height of about 50 centimeters.
The individual species differ in flower and leaf color. White, pink, red and mixed-colored flower umbels are conceivable on the bush, as well as green and yellow leaves. Overall, summer spars develop a little more in width than in height. A shrub that is 1.5 meters high will be about two meters wide. Spiraea japonica grows very compact by nature. Its alternate, lanceolate leaves remain very filigree like the entire plant. In the spring, the leaves of the Sommerspier first sprout red before turning green or, in cultivated forms, golden yellow. The shoots lignify quickly, but usually remain very thin and flexible. On the one-year shoot, white, pink or reddish flower umbrellas form terminally from May,
Pink and red flowers
- Anthony Waterer (Rote Sommerspiere): most common variety, reddish flower, height of growth up to 80 centimeters
- Sapho: Variant by Anthony Waterer, slightly darker red flowers
- Little Princess: many pink flowers, dwarf sprigs, height of growth 40-50 centimetres
- Alpina: light pink flowers, even flatter and more compact than Little Princess
- Superstar (Denistar): bright red flowers, up to 1.5 meters tall
- Froebelii (hedge spiers): light pink flowers, up to 1.5 meters tall, ideal hedge plant
- Neon Flash: dark pink flowers, up to 100 centimeters tall
- Albiflora: white flowers, growth height up to
- Snowmound: white flowers with a slightly yellowish-red shimmer, fast-growing (20-40 cm/year), up to two meters tall
- Genpei: two-tone panicles of flowers (pink and radiant white), height of growth up to 75 centimetres
- Shirobana (Harlekin-Spiere): strong change-colored flowers in the colors white, pink to blue-red, often individual flowers are multicolored, height of growth 60-120 centimeters
- Golden Princess: striking golden-yellow foliage, pink flowers (slightly smaller), height of growth up to 50 centimetres
- Magic Carpet: golden yellow foliage, pink flowers, height of growth up to 50 centimetres
- Goldflame: pink flowers, slightly yellowish foliage, the tips of the leaves turn red in the sun, height of growth up to 100 centimeters (hedge plant)
- Candlelight: deep pink flowers, soft yellow foliage, height of growth up to 60 centimetres
In nature, the Spiraea japonica occurs as a perennial shrub, especially in riparian areas, moors and wetlands along rivers and forest edges. The light-loving spirea particularly likes a place in the direct sun, but light partial shade is also sufficient for the formation of flowers. Young summer spars need slightly moist, well-drained soil during the growing season, later they also cope well with dry periods. Only waterlogging and compacted soils have an unfavorable effect on their growth. The sunnier the shrub is, the more lush its flowers will be.
Light requirement: full sun to sunny, light semi-shade
Soil: any normal garden soil that does not tend to waterlogging
The flowering shrub can be planted all year round as long as the ground is frost-free. The best time to plant new trees is in spring and autumn. Since the shrubs grow more in width than in height, care must be taken to ensure sufficient planting distance. In the case of low-growing species, about three plants are planted per meter, in the case of tall species, one plant per meter is quite sufficient. In the early days it is important to water the young plants regularly.
Before planting, the plant should be checked for dead shoots and kinks and these should be cut out. A careful pruning of the roots by about a third makes it easier for the plant to grow into the new location. Just prior to planting, the summer spar pot is placed in a bucket of water for about an hour. The bushes must not come into the ground without water. If the root ball is dry, the plant will not be able to connect to its new location because the soil in the garden will not stick to its roots. It is also necessary to loosen the soil well before planting. If necessary, a little compost can also be worked in so that the young spirea has a rich supply of nutrients.
- Planting hole: at least root depth, twice the diameter
- Planting distance: 30-100 centimeters (depending on growth height)
- If the soil is dry: first fill in a little fresh soil and water extensively
- Plant only after the water has been absorbed
- fill with humus garden soil
- Planting depth: flush with ground level
- Cut back the shoots by about a third
- then water as needed
watering and fertilizing
The summer spar is a very undemanding plant. It needs neither fertilization nor additional irrigation water on moderately nutrient-rich soils, as it copes well with drought. Only young plants should be watered regularly in the first year, as they do not yet have a well-developed root system. Adult plants only need to be watered with a little water during really long periods of drought or extreme heat. A thick layer of mulch on the ground protects against too much evaporation. If the Japanese spirea is very shady, the loss of flowering can be counteracted with a little fertilizer (e.g. horn shavings).
Individual species of summer spars grow up to two meters high in old age. However, most varieties grow moderately into a compact bush between 50 and 80 centimeters. In principle, a cut is not absolutely necessary. If the plant is used to stabilize slopes, it can be left to its own devices and become wild. As a hedge plant, it tolerates pruning very well and can be cut back at any time. However, in order to maximize flowering, pruning after flowering in the fall makes sense. Even a radical pruning down to about 30 centimeters above ground level is accepted without complaint after the winter. This measure even boosts flower development.
1. Pruning for maintenance
Of course, a Japanese spirea will generally survive the years without pruning. However, to ensure that the plant always looks pretty, blooms profusely and remains less susceptible to diseases, it should be thinned out a little once a year.
- Growth rate per year: 5-15 centimeters
- Cutting time: possible at any time
- Prune in spring before new shoots for abundant blooms
- remove all dead and dried shoots
- Shorten weak shoots close to the ground
- Cut inward shoots
- Cut older branches (four years and older) close to the ground
2. Radical pruning
If the summer spar is left to its own devices and not cut at all, it can happen that too little sunlight falls into the inner and lower areas and the plant wilts from the inside. In these cases, only a radical rejuvenation cut can help, in which all branches are cut back to 20 centimeters. Radical cuts should always be made in winter, otherwise the plant will find it difficult to cope with the measure.
3. Rejuvenation pruning
Older plants can become less compact over time and age from within. If you don’t want to cut back radically and therefore want to do without flowering for a while, you can do this in several steps over three years:
- Year: shorten about a third of the branches to the height of the first young shoot (about 20 cm high). Distribute the cut evenly over the entire plant.
- Year: shorten another third of the branches. Make sure that shoots are cut that were not shortened in the previous year. Spread evenly over the bush.
- Year: prune the remaining third of shoots that have not yet been pruned. After the third year, the shrub is completely rejuvenated.
Larger summer spars are ideal for hedge planting. Planting distances of about half the growth width should be maintained here (depending on the species, about 40-80 centimetres). Hedges from the Sommerspar are less strict in their appearance than those from coniferous trees. The flowering shrubs are very tolerant of pruning and quickly sprout again. The best time to trim a hedge is after flowering or in winter. In principle, a hedge should always be cut when the sky is frost-free and slightly cloudy. A slightly tapering shape (trapezium) prevents balding.
The Spiraea japonica is considered an invasive plant that can spread aggressively in a humid, temperate climate. It easily creeps into the edges of meadows and displaces the original vegetation there. Wild forms of summer spar tend to spread invasively. The shrubs produce thousands of small seeds that are viable for a very long time even under the most unfavorable circumstances. Cultivated forms usually do not show this behavior.
The easiest way is a targeted propagation via cuttings. The seeds can also be sown in soil, but in cultivated forms the young plant can differ greatly from the mother plant.
- Cuttings are cut in summer
- Cut about 20 centimeters long, woody shoots
- Cut the shoot tip
- cut off or scrape off the bark on one side at the bottom with a knife
- plant about five centimeters deep in moist garden soil
- propagation in the open air
- partially shaded spot in the garden
- water regularly until winter
The rooted cuttings can then be transplanted to a sunny spot next spring.
Most species of Spiraea japonica are hardy here and do not require any special protection from frost. Only new plantings and young plants should be provided with a layer of mulch or leaves in the root area. A hard pruning before new growth promotes flowering.
diseases and pests
Spars are generally very robust and frugal small shrubs. It is therefore not surprising that they are largely resistant to diseases and pests. Occasionally aphids appear in spring, which can be combated with household products (soapy water).
If you are looking for an easy-care ornamental shrub with a long flowering period, you are on the safe side with the Sommerspare. Dwarf forms are up to 50 centimeters high and slightly wider. They are ideal as ground cover or for planting on slopes. Higher-growing species are ideal shrubs for loose hedges, which bloom continuously between May and October and are also very tolerant of pruning. An absolute all-round plant that thrives in almost any sunny location and does not require much care.