Japanese Azalea 'Signalglühen'

Japanese Azalea 'Signalgluhen' (Rhododendron 'Signalglühen') burns in the garden like a signal fire. Its large flowers, 4.5-4.7 cm across, are a deep red lit from within by orange - a tone you can pick out from the far end of the plot. It flowers in May and June.

Use it wherever a bright patch is needed: the edge of a path, a slope, a planting with conifers, a heather garden. The shrub grows to about a metre tall, noticeably bigger than the modern dwarf cultivars, so it also works well in the second row. Hardiness is high, down to -29 °C; it asks only for acidic soil and sheltered partial shade.

Key characteristics:

• What makes it special: The name means "signal glow", and the colour really does work as a signal: red lit with orange, readable from the far end of the garden.
• Dimensions: Grows up to 1 m tall.
• Hardiness: Hardy down to -29 °C (USDA zone 5).
• Flowering: In May-June it blazes with rich red, orange-tinted flowers of 4.5-4.7 cm.
• Light: Happiest in partial shade or dappled light: morning sun, a little shade at midday and a snug spot sheltered from strong wind.
• Soil: Loves acidic soil at pH 5.0-5.5, rich in humus and evenly moist. The one thing it will not take is standing water, so good drainage is a must.
• Watering: Water moderately but regularly: the shallow roots dislike drying out and standing water in equal measure.
• Care: Mulch with bark or pine needles, leave the soil under the bush undisturbed, and trim the spent blooms right after flowering.
• Landscape use: Low edging, heather and rock gardens, underplanting for rhododendrons; lovely in groups and containers in partial shade.
• Origin: Raised at the Hachmann nursery in Barmstedt, Germany, in 1964; it is the parent of 'Fridoline', 'Canzonetta' and 'Brunella'.