In addition to the rose, the rhododendron genus, including the azalea, is one of the most important and popular ornamental trees in Germany. This is hardly surprising in view of the graceful flower shapes and the enchanting blaze of colour. Currently 1,150 rhododendron species are known, just over 4,000 varieties that can be cultivated in Germany and over 30,000 varieties worldwide. In Germany and Europe, however, only 10 species are suitable for the garden, which are presented below in addition to the most popular rhododendron and azalea varieties.

Rhododendron species in Germany and Europe

Rhododendron caucasicum PALLAS (1788) – Kaukasus Rhododendron

  • Growth form: shrub
  • Size: 30cm to 100cm
  • Flowering time: April-May
  • Flower color: creamy white to yellow, rarely soft pink
  • hardy to: – 29° Celsius

Rhododendron ferrugineum L. (1753) – Rostblättrige Alpenrose

  • Growth form: shrub
  • Height: 150cm
  • Flowering period: June-July
  • Flower color: deep pink
  • hardy to: – 24° Celsius

Rhododendron hirsutum L. (1753) – Wimpy Alpine Rose

  • Growth form: shrub
  • Size: 100cm
  • Flowering period: June-July
  • Flower color: soft pink, rarely white
  • hardy to: – 24° Celsius

Rhododendron lapponicum (L.) WAHLENB. (1812)—Alaska Rhododendron

  • Growth form: shrub
  • Size: up to 100 cm
  • Flowering period: January to April
  • Flower color: pink-violet to crimson
  • hardy to: – 29° Celsius

Rhododendron luteum SWEET (1830) – Pontische Azalee

  • Growth form: shrub
  • Size: up to 200 cm
  • Flowering period: May-June
  • Flower color: yellow
  • hardy to: – 24° Celsius

Rhododendron myrtifolium SCHOTT & KOTSCHY (1851) – Rhododendron Simonkai

  • Growth form: shrub
  • Size: 60cm
  • Blütezeit: Mai
  • Flower color: pink
  • hardy to: – 24° Celsius

Rhododendron ponticum L. (1762) – Rhododendron

  • Size: up to 800 cm
  • Flowering period: May-June
  • Flower color: pale pink, violet, crimson
  • hardy to: – 24° Celsius

Rhododendron smirnowii TRAUTV. (1885) – Smirnows Rhododendron

  • Growth form: shrub or tree
  • Size: up to 400 cm
  • Flowering period: May-June
  • Flower color: pink to purple
  • hardy to: – 29° Celsius

Rhododendron tomentosum HARMAJA (1990) – Sumpfporst

  • Growth form: shrub
  • Size: 30cm to 120cm
  • Flowering period: May-July
  • Flower color: white
  • hardy to: – 18° Celsius

Rhododendron ungernii TRAUTV. (1885) – Hungarian Rhododendron

  • Growth form: shrub or tree
  • Size: up to 700 cm
  • Flowering period: June-July
  • Flower color: white fading into pink
  • hardy to: – 24° Celsius

Popular rhododendron varieties

The varieties are hybrids that have been created over the decades through ever new crossings and breedings and can often be traced back to several species as parents. They have inherited advantageous characteristics from their parents that make them so popular with hobby gardeners, such as winter hardiness, dense growth and lush inflorescences.

Large-flowered rhododendrons

This variety includes rhododendrons that are between 200 cm and 500 cm tall and usually have 20 individual flowers or more on their flower stalks:

Cunninghams White

  • Flowers: white single flowers
  • Flowering time: early to mid-May
  • Leaves: oblong, dark green leaves, evergreen
  • Growth: upright, broad bushy growth
  • Growth size: up to 200 cm
  • Location: sunny to semi-shady

Furnivalls Daughter

  • Flowers: bright pink single flowers
  • Flowering period: May to early June
  • Leaves: oblong, dark green leaves, evergreen
  • Growth: upright, broad bushy growth
  • Growth size: up to 200 cm
  • Location: sunny to semi-shady

Blue Peter

  • Flowers: lilac-blue with a dark red spot, funnel-like individual flowers
  • Flowering period: May to early June
  • Leaf: oblong, dark green, evergreen
  • Growth: upright, broad bushy
  • Growth size: up to 100 cm
  • Location: sunny to semi-shady

Goldbukett

  • Flowers: creamy yellow, funnel-like flowers
  • Blütezeit: Mai
  • Leaves: oblong, dull green, evergreen
  • Growth: upright, broad bushy
  • Growth size: up to 100 cm
  • Location: sunny to semi-shady

Brasilia

  • Flowers: orange-pink-yellow, individual flowers with red stamens
  • Flowering time: mid-May to late May
  • Leaf: oblong, dull green
  • Growth: upright, broad bushy
  • Growth size: up to 150 cm high and wide
  • Location: sunny to semi-shady

Progress

  • Flowers: Bright pink flowers with a dark red center and a wavy edge
  • Flowering time: mid to late May
  • Leaf: oblong, glossy dark green, evergreen
  • Growth: upright, bushy
  • Growth size: up to 150 cm
  • Location: sunny to semi-shady

Red Jack

  • Flower: red single flowers
  • Flowering time: early to mid-May
  • Leaf: oblong, dark green, evergreen
  • Growth: upright, broad bushy
  • Growth size: up to 200 cm
  • Location: sunny to semi-shady

Small-flowered rhododendron

Although the differentiation according to the size of the flowers cannot be made exactly because the transitions are quite fluid, this feature has nevertheless prevailed. It should be noted that small-flowered does not necessarily mean small in stature.
Yakushimanum Hybrids or Ball Rhododendron

Their homeland is the sunny mountain slopes of Japan. Decades of breeding have also made this variety suitable for the local regions. Their small size makes them ideal rhododendrons for small gardens, rock gardens and grave plants.

Barbarella

  • Blossom: a play of colors from yellow, pink, red and orange
  • Flowering time: from mid-May
  • Leaf: narrow, elliptical, deep green
  • Growth: petite
  • Growth size: up to a maximum of 70 cm
  • Location: sunny to semi-shady

Heinje’s Magic Flute

  • Flower: light pink, slightly wavy edge
  • Flowering time: from mid-May
  • Leaf: dark green
  • Growth: small and compact
  • Growth size: up to 120 cm
  • Location: sunny to semi-shady

Kalinka

  • Flower: ruby ​​pink, slightly darker at the edge
  • Flowering time: from mid-May
  • Leaf: slightly shiny dark green
  • Growth: rounded and compact
  • Growth size: 120 x 160 cm
  • Location: sunny to semi-shady

Japanese azaleas

These varieties also belong to the small-flowered rhododendrons, although they are so small that they are ideally suited for a magnificent grave planting, the small front garden or as a container plant.

Little song

  • Flowers: carmine red, double flowers
  • Flowering period: late May to early June
  • Leaves: small, oblong, grey-green, evergreen
  • Growth: stocky growth, slow-growing
  • Growth size: up to 40 cm
  • Location: sunny to semi-shady

Fridoline

  • Flowers: pure red, trumpet-like individual flowers
  • Flowering period: late May to early June
  • Leaves: small, oblong, grey-green, evergreen
  • Growth: stocky, slow-growing
  • Growth size: up to 40 cm
  • Location: sunny to semi-shady

Kermesina Rose

  • Flowers: pink with a white edge, trumpet-like individual flowers
  • Flowering period: late May to early June
  • Leaves: small, oblong, grey-green, evergreen
  • Growth: stocky, slow-growing
  • Growth size: up to 60 cm
  • Location: sunny to semi-shady

blizzard

  • Flowers: pure white, large-flowered, trumpet-like individual flowers
  • Flowering period: late May to early June
  • Leaf: small, oblong, grey-green
  • Growth: stocky, slow-growing
  • Growth size: up to 60 cm
  • Location: sunny to semi-shady

Deciduous Rhododendron – Deciduous Azaleas

This variety is characterized by the fact that, in addition to a rich and colorful bloom, they shed their foliage after it has turned autumnal. Therefore, these flowering shrubs offer a changing picture over the course of the year.

Golden Eagle

  • Flowers: bronze-yellow, funnel-shaped individual flowers
  • Flowering period: late May to early June
  • Leaves: elongated, dull green, summer green
  • Growth: upright
  • Growth size: up to 200 cm
  • Location: sunny to semi-shady

Parking fire

  • Flowers: Dark red, trumpet-like single flowers, slightly fragrant
  • Flowering time: mid-May
  • Leaves: oblong, shiny dark green, deciduous
  • Growth: upright and wide
  • Growth size: up to 250 cm high and 100 cm wide
  • Location: sunny to semi-shady

Goldtopas

  • Flowers: Bright yellow, trumpet-shaped individual flowers
  • Flowering time: end of May
  • Leaves: oblong, shiny dark green, deciduous
  • Growth: upright and wide
  • Growth size: up to 150 cm high and 100 cm wide
  • Location: sunny to semi-shady

Dwarf and Wild Rhododendron

Thanks to their compact shape and small flowers, the dwarf and wild rhododendrons are often found in pots as patio or balcony decorations and adorn many a house entrance. They are also excellent for the creatively designed rock garden, the imaginative Japanese garden or the loving planting of graves.

Azurika

  • Flowers: deep violet-blue, funnel-like individual flowers
  • Flowering time: early to late May
  • Leaf: small, oblong, grey-green, evergreen
  • Growth: compact, slow-growing
  • Growth size: up to 100 cm high and wide
  • Location: sunny to semi-shady

Scarlet Wonder

  • Flowers: Bright red, trumpet-like single flowers
  • Flowering time: early to mid-May
  • Leaves: oblong, fresh green, evergreen
  • Growth: upright, broad bushy
  • Growth size: up to 60 cm high and wide
  • Location: sunny to semi-shady

Luisella

  • Flowers: lilac-blue, trumpet-like individual flowers
  • Flowering time: mid to late May
  • Leaves: small, oblong, grey-green, evergreen
  • Growth: stocky, slow-growing
  • Growth size: up to 40 cm high and wide
  • Location: sunny to semi-shady

Ludlowii Wren

  • Flowers: pure yellow, funnel-like individual flowers
  • Flowering time: early to mid-May
  • Leaf: small, oblong, leaves, evergreen
  • Growth: compact, slow-growing
  • Growth size: up to 60 cm
  • Location: sunny to semi-shady

Indian Azaleas – Indoor Azaleas

Despite its name, this variety does not come from India, but is native to East Asia. Since these plants do not tolerate frost, they have found their way into the homes of many hobby gardeners as popular houseplants. Their flowering time is between November and May, so that they delight people with their colorful splendor during the cold and dark season.

No

  • Flowers: Two-tone blue-pink and white on the inside, white border
  • Flowering period: August to November
  • Size: up to 60 cm

John T.D. Lewelyn

  • Flower: Two-tone pink and white inside, bright pink center
  • Flowering time: November to April
  • Size: 50cm

Charly Karl Glaser

  • Flower: Deep purple on the inside, deep red on the edge
  • Flowering period: August to November
  • Size: 40cm to 50cm

Fragrant Rhododendren

Not so easy to include a scent in the breeding with all the positive properties that a rhododendron is supposed to offer. With some varieties, however, this has been extremely successful:

Admiral Piet Hein

  • Flower: delicate lilac to white
  • Flowering time: May and second flowering in October
  • Size: 110cm to 400cm
  • Growth form: upright, dense shrub
  • hardy to: – 24° Celsius

fragrance cloud

  • Flower: soft pink and white
  • Flowering period: May to June
  • Size: up to 200 cm
  • Growth form: bushy shrub
  • hardy to: -20° Celsius

Summer scent

  • Flower: pink and white
  • Flowering period: May to June
  • Size: 100 cm high and 100 cm wide
  • Growth form: shrub
  • laubabwerfende Kind

Kaminduft

  • Flower: deep ruby ​​red
  • Flowering period: May to mid-June
  • Size: 160 cm high and 170 cm wide
  • Growth form: broad shrub
  • laubabwerfende Kind

Azaleodendron – the rarity

A cross between deciduous azaleas and evergreen rhododendrons has been successful in a small group of plants. Their visual appearance also signals this combination. The result is plants that keep their foliage through the winter and don’t shed it until spring.

Govenianus

  • Flower: light violet
  • Flowering time: June
  • Size: 90 cm high, 110 cm wide
  • semi-evergreen shrub
  • pleasant sweet scent

Williamsianum Hybrids – Bell Rhododendron

The bell-shaped rhododendrons set colorful accents in the garden early in the year with their spherical flowers. Since the foliage is oval in shape to match the shape of the flowers, these varieties are always finding new fans among hobby gardeners.

Trumpet

  • Flower: bright red bells
  • Flowering time: April to May
  • Size: 70 cm high and 110 cm wide
  • dark green, evergreen leaves
  • very hardy

August Lammen

  • Flower: bells in deep ruby ​​red
  • Flowering period: late April to late May
  • Size: 120cm high, 140cm wide
  • large, rich green foliage
  • extremely hardy

Garden director Rieger

  • Flowers: cream-white bells with red markings
  • Blütezeit: Mai
  • Size: 140cm high, 170cm wide
  • Leaves: green, glossy
  • hardy

Jackwill

  • Flower: pink bells
  • Flowering period: late April to mid-May
  • Size: 60 cm high, 110 cm wide
  • Leaves: light green
  • hardy

Conclusion
Nobody can escape the magic of a blooming rhododendron. The ornamental tree from the heather family grows very slowly and only reaches its final growth height after more than 10 years; however, the beautiful flowers also appear on the very young plants. This also applies to azaleas, which have been part of the rhododendron genus for more than 200 years. The variety of species and varieties is so breathtakingly diverse that every hobby gardener can discover their personal favorites here.

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