Astilbe Species: Arendsii, Chinensis, Japonica & More

Your astilbe reaches 4 feet with dramatic cascading plumes while your neighbor’s compact version stays under 12 inches with star-shaped blooms. The difference comes from species group classification, with each of the five major groups producing distinct flower forms, foliage textures, and bloom periods[1]. Understanding these groups transforms your shade garden from random plantings into strategic displays.

💡Master comprehensive astilbe cultivation from variety selection through design strategies with our complete astilbe guide for shade garden excellence.

Understanding Astilbe Classification

Astilbe classification is much more than simple variety names. The genus contains approximately 20 species native to eastern Asia and eastern North America, and there are breeders who breed hundreds of hybrids of these species[8]. These crosses divided them into separate clades, that were separated by genes specific to their parent species. Depending on which group you select[7][8], height ranges from 6 inches to 5 feet. Bloom times range from late May through September, allowing you to have a continuous colouring when you’ve hit several groups[8].

Understanding species groups allows precise plant selection for bloom time, height, and growing conditions.

Arendsii Hybrids: The Garden Workhorses

The market in the United States is dominated by the arendsii group. More than 95% of astilbes sold in the United States come from this group[1]. The hybrids were developed by German nurseryman Georg Arends during the 1920s by crossing Astilbe chinensis, Astilbe japonica, Astilbe thunbergii, and Astilbe astilboides. Plants that produced with such complex parentage are better performing in the garden than those with strictly straight species. The hybrids have dense flower plumes in colors ranging from white through pink, red, lavender, and purple[2]. Plants generally grow 24 to 36 inches tall; they have a spread of 18 to 24 inches[2].

💡Match plant sizes to specific garden positions with our comprehensive height ranges by species covering dwarf through extra-tall selections.

These hybrids of Arendsii produce ternately compound leaves with sharply toothed leaflets radiating red, bronze, or green foliage[6]. Depending on cultivar, the leaves mature to glossy or matte finishes. Flower panicles grow up the slender upright stem above the foliage mounds, which forms a layered display[6]. These hybrids grow mostly in early to mid-summer, to fill the void between spring bulbs and late-summer perennials[3].

Popular Arendsii Cultivars

Popular varieties include:

• Fanal – Deep red flowers with bronze foliage
• Bridal Veil – Pure white blooms
• Amethyst – Lilac-purple plumes[3][7]

Growing Requirements

The arendsii group needs consistently moist, organically rich soil, part shade to full shade[6]. Plants grow in zones 4 to 8 where they flourish during cold winters, but can tolerate hot, humid summers only with adequate moisture[2][6]. Soil should never become dry during the growing season. A 2-3 inch layer of compost mulch does wonders in keeping the water in the soil and keeping roots cool too[6]. These hybrids begin sprouting very quickly, maturing within 2-3 years of planting[1].

Astilbe Chinensis: The Drought Tolerant Option

Astilbe chinensis, a group that has proved to be exceptionally drought tolerant, performs better in drier conditions than other kinds of astilbes[1][5]. This species produces late bloom and extends flowering over the late summer and early fall period[1]. Foliage is deeply incised, coarsely textured, and of bronze-green coloring[1][5]. The leaves have a distinct appearance from the softer-textured arendsii foliage, and this is one of the initial distinguishing features of chinensis plants in mixed plantings.

Flowers occur on narrow branched panicles as opposed to compact pyramidal clusters of arendsii hybrids[1]. These colors are pink, lavender, purple, and white[4]. Bloom season is from mid-summer to August, giving color for the blooming of many perennials[3][5].

💡Plan continuous flowering displays by understanding bloom times by species including early japonica, mid-season arendsii, and late chinensis.

Chinensis’s prolonged blooms provide long bloom time thus making this plant useful as garden interest sustainers. The species is moderately tolerant to drought once settled, but in moist soil, its performance in a garden is greatly improved[1].

Size Variations in Chinensis

Chinensis plants differ greatly in size[7]. Dwarf varieties such as Pumila grow in size of 10-12 inches and spread slowly by rhizomes to form successful groundcovers for shady areas[7][8]. Standard chinensis types are between 12 to 24 inches[7]. The tight growth mode fits small gardens, containers, and front-of-border planting[3][4]. Plants will have more tolerance for the sun than other plant groups if they are given constant water[4][5]. This sun tolerance expands places to plant into gardens exposed to mixed lighting.

Astilbe Japonica: Early Season Color

Astilbe japonica stands out well because it grows in early bloom time and has characteristic foliage[1][5]. This group flowers in late spring to early summer[3], typically several weeks before hybrids of arendsii start[3][7]. Combination of early flowering with mid- and late-blooming groups also lengthens the astilbe season. Plants are about 20 to 36 inches tall and vary according to cultivar[7][9].

The glossy green leaves start coming out in spring, tinged with red or bronze leaves give a very attractive foliage color before flowers appear[1][5][9]. In the proper growth conditions during the whole season, the leaves have glossy appearance[9]. Flowers develop in dense pyramidal clusters overlying the foliage and held vertical[1][9]. They are white, pink, red, and peach[3][7].

💡Discover how color options vary within each species group by exploring our detailed colors within species guide for precise cultivar selection.

In shade gardens, its compact pyramidal formation gives bold vertical accents.

Early-blooming japonica varieties solve the common problem of sparse color in late spring shade gardens.

Growing Japonica Successfully

Japonica plants grow between 1.5 and 2.5 feet tall and wide and may need partial to full shade and moist, well-drained soils[9]. They can absorb more sunshine in cooler summer temperatures, but require sun protection in warm climatic regions of the year[7]. Hardiness zones range from 4 to 9[9]. The common cultivars are Deutschland with pure white flowers, Montgomery with dark red flowers and bronze foliage, and Rheinland with bright pink plumes, to name just a few. Due to their reliable performances and color for the early season, these cultivars continue to be readily available at garden centres[3][7].

Simplicifolia Group: Delicate Stars

Simplicifolia group yield the smallest, most delicate astilbes[1][3]. Plants form compact mounds, typically reaching the height of 12 to 20 inches[3][7]. The shiny, mid-green leaves look lobed instead of divided as is the case for most other species groups[1]. This ‘simple’ foliage provides a refined finish, even without flowers. Leaves tend to reflect bronze or reddish tones, providing interest to foliage[3][4].

Flowers appear as open, airy panicles with star-shaped individual blooms rather than dense plumes[1][3]. This delicate flower structure creates a lighter, more ethereal effect compared to the bold plumes arendsii hybrids develop. Colors include white, pink, and salmon-red[3][7]. Bloom time is found from mid to late summer[3][7]. A higher diversity of star-shaped flowers than dense-plumed varieties, which attract different pollinators, increases biodiversity even in gardens.

Plants made by Simplicifolia take longer to establish than those that are made by arendsii, take around 3 years to reach adulthood[1]. Plants are compact with little spreading once established. Small size suitable for rock gardens, container plantings, and front-of-border positions[3][4]. While flowering, plants tolerate full shade better than larger species groups[1]. The most popular cultivar is Sprite, which has shell-pink flowers and bronze-tinged foliage[7][8]. This cultivar under different growing conditions performs well.

Astilbe Thunbergii: Dramatic Cascades

Astilbe thunbergii is known for its tall stature and its iconic flower structure[1][3], producing the most dramatic effect. Plants are about 36 to 48 inches tall, towering over the other categories of species. In shade gardens, the tall stems exert vertical impact and lift the eye upward. The colored greenery of foliage appears glaucous or bluish-green, while other groups have dark green leaves[1][3].

Distinctive Characteristics

Flowers take the form of broad, nodding clusters that arch outward and downward rather than upright[1][3]. This cascading habit inspires dynamism and grace, working well close to water features or pathways[3][4]. The open panicle structure looks less dense compared to the japonica or arendsii flowers; the individual flowers are clearer[1]. It has the following colors, white, pink, or coral-pink[3][7]. Bloom time falls at mid to late summer[1][3].

The unique flower shape gained thunbergii cultivars nicknames. With large, drooping coral-pink plumes of similar appearance to ostrich feathers, Ostrich Plume[3][7]. Professor van der Wielen produces cascading white flowers[3][7]. The cultivars function best as specimen plants or with groups in their dramatic form. Plants need constant moisture and do well in zones 4 to 8[3].

Cultural Requirements Across All Groups

Albeit differing, all astilbe species groups have some fundamental cultural needs in common. Plants require uniformly moist and naturally-rich soil that drains well[1][6][8]. Soil should not only have high amount of organic matter but be amended with compost or leaf mold year after year[6][8]. Best conditions are partial shade and plants can tolerate complete shade but less flowering[1][8]. Chinensis varieties are the only ones that can withstand significant sun exposure[1][5].

Water Requirements

Water needs are non-negotiable across all groups. Soil drying = rapid degenerative foliage — leaf browning and curling within a few days[7][8]. Insufficient moisture is critical for plants, as it leads to early dormancy[8], and leaves start to disappear as of mid-summer. This decline is prevented by regular watering in dry times. Mulching the soil with 2 to 3 inches of organic material is a good thing to keep the moisture in soil consistent moisture use to preserve moisture in all types of soil with both.

Never let soil dry out completely during the growing season—astilbes are unforgiving of drought stress.

Division and Maintenance

Division maintains plant vigor across all species groups. Clumps must be divided every 3–4 years if centers are crowded or flowering diminishes[6][7]. The optimally generated results are from early spring division when new growth is emerging[7]. Dig entire clumps and divide into sections with three to five eyes each. Plant the division very strongly deep, much like the original plant. Well water and maintain consistent moisture until new growth establishes.

Creating Extended Bloom Seasons

The choice of types of astilbe also causes a beneficial period of bloom throughout the whole cultivated season by effectively planting astilbe species clusters. Early japonica are shown to flower in late May[3][7]. Midseason arendsii hybrids peak in June and July[3][7][8]. Late chinensis and thunbergii varieties continue through August and September[1][3][7]. The three to four months of continuous color from a single genus is provided by this succession.

Height Stratification

Different heights of the groups in a shade garden offer layering chance:

• Front border (6-18 inches) – Dwarf chinensis and simplicifolia breeds
• Mid-border (18-36 inches) – Arendsii and japonica plants[2][7][9]
• Background (36-48 inches) – Tall thunbergii plants[3][7]

This kind of organic-scale stratification contributes depth and visual interest without any special plant genera.

Companion Planting Considerations

The growth traits of plants contribute to the decisions on companion planting. Fine-textured the leaves of arendsii and japonica in contrast to the bold hosta foliage. Bronze leaved cultivars from any group complement chartreuse or blue leaved hostas. Glossy japonica and simplicifolia foliage reflects light in deeper shade and brightens dark corners[1][9]. Coarse chinensis leaves give textural weight to delicate fern pals.

So, the overall design of the garden includes varying flower form. Dense, upright plumes comprising arendsii and japonica clustered in a vertical position form bold vertical statements[1][6][9]. The flowers of the florals of arendsii and japonica, especially the open, cascading thunbergii, generate open, cascading and active movements[1][3]. Flowery soft cascading thunbergii flowers[1][3]. Gossamer, delicate simplicifolia stars offer airy accents[1][3]. Mixing flower forms in a planting creates visual rhythm and prevents repetitive patterns. Set each form in drifts of 3 to 5 plants so each type can be put under a maximum groupage for impact.

Choosing the Right Species Group

Maintenance requirements for each of the three kinds are determined by species group selection. Hybrids of fast-evolving arendsii take up space relatively quickly but divide more often[1][6]. Slow growing simplicifolia plants require less frequent division but require more time to make complete displays[1]. Chinensis varieties need to be monitored for dispersal in order not to spread too broadly in small gardens[1][8]. Conversations of species group characteristics to the hours available for the current maintenance period help maintain success long-term and successful.

Selection Guide by Situation

Awareness of groups of astilbe species groups gives the option of exactly the species to select a specific plant species for a specific type of garden situation:

• Early season color in compact spaces – Choose japonica[3][7][9]
• Reliable mid-summer performance with maximum color range – Select arendsii[1][2][3]
• Sunnier locations or drier sites – Plant chinensis[1][5]
• Delicate accents in small gardens or containers – Use simplicifolia[1][3]
• Dramatic vertical impact in large shade gardens – Install thunbergii[1][3][7]

Each group fulfills their proper design role but simple variety selection cannot.

Building a Successful Astilbe Garden

💡Explore the complete range of cultivars beyond species classifications with our comprehensive all varieties guide covering hundreds of named selections.

Numerous species groups contribute to fruitful varieties of success in astilbe gardens that develop extended periods of bloom season, various heights and types of flowers. Begin by measuring light, cover moisture and space in your garden. Match species groups with your site conditions instead of forcing the plants into poor placement. Plant, 3-5 species per type to add visual effect to the garden groups of 3-5. Combine the early, mid and late-blooming groups for continuous color from late spring through early fall.

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Key Sources:

[1] Astilbe Groups | Walters Gardens, Inc.

[2] Astilbe x arendsii | North Carolina Extension Gardener Plant Toolbox

[3] Astilbe Groups | Bloomin Designs

[4] All About Astilbe: Everything You Need to Know! | Florissa

[5] Plants: Astilbe | Northeast Nursery

[6] Astilbe × arendsii ‘Rotlicht’ RED LIGHT | Missouri Botanical Garden

[7] Growing Astilbe in Iowa | Yard and Garden – Iowa State Extension

[8] Astilbe | PlantFacts – The Ohio State University

[9] Astilbe japonica | North Carolina Extension Gardener Plant Toolbox