Introduction & History

No rose captures the elusive dream of a blue rose quite like 'Blue Moon,' the iconic silvery lilac hybrid tea that has enchanted gardeners since its introduction by Mathias Tantau in 1964. Known across Europe as 'Mainzer Fastnacht' and in France as 'Sissi,' this variety comes closer to blue than perhaps any other large-flowered rose, its elegant blooms suffused with a silvery lavender-lilac that deepens in cool weather to approach a true blue-mauve. But it is the fragrance that elevates Blue Moon into the pantheon of great roses: an intense, intoxicating perfume blending classic damask sweetness with citrus and spice that has won it the coveted James Alexander Gamble Fragrance Medal. For over six decades, Blue Moon has been the standard-bearer for the blue rose class, the variety against which all subsequent lavender and lilac roses are measured, and a perennial favorite in gardens where fragrance and romance take precedence over ease of cultivation.

Breeding History

'Blue Moon' was bred by Mathias Tantau Jr. at Tantau Roses in Uetersen, Germany, and introduced in 1964 under the registration name 'TANnacht.' In Germany it is sold as 'Mainzer Fastnacht' (Mainz Carnival), in France as 'Sissi,' and in English-speaking markets as 'Blue Moon' or 'Blue Monday.' The parentage is an unnamed seedling crossed with 'Sterling Silver,' inheriting the lilac coloring and intense fragrance of its famous parent while adding considerably more vigor and better plant health. Blue Moon won numerous international awards including the Rome Gold Medal in 1964, and later received the American Rose Society's James Alexander Gamble Fragrance Medal, confirming its place among the most fragrant roses ever bred. It opened the door for an entire generation of 'blue' rose breeding.

Flower Form & Fragrance

Blooms are large, 10-12 cm across, with 35-40 petals arranged in a classic high-centered hybrid tea form. The color is silvery lilac to lavender-blue, intensifying in cool weather and softer in heat. Individual blooms are borne on long stems, one per stem, with a graceful, elongated bud stage that is particularly beautiful. The fragrance is exceptional and legendary: a powerful, sweet damask-citrus perfume with spicy undertones, rated among the strongest of any hybrid tea. The scent is detectable from several meters away and fills garden spaces on warm evenings. Petal substance is moderate, with blooms performing best in dry conditions.

Garden Design & Uses

'Blue Moon' deserves a prominent position near seating areas, windows, and pathways where its extraordinary fragrance can be savored. It pairs magically with silver and white companions: lamb's ear, white lavender, artemisia, and pale pink roses create a romantic, dreamy garden vignette. Combine with deep purple clematis or salvia for striking tonal depth. Use in sensory gardens, moonlight gardens, and cottage garden settings where its unusual color glows at dusk. Avoid placing in hot, exposed beds where the lilac tones may wash out, and do not combine with harsh orange or scarlet roses that overwhelm its subtle coloring.

Growth Habit & Hardiness

'Blue Moon' grows as a tall, upright hybrid tea reaching 100-140 cm tall with a spread of 60-80 cm. The habit is strong and somewhat angular, with long, straight stems ideal for cutting. Foliage is large, medium to dark green, and semi-glossy with a leathery texture. Thorns are prominent and numerous, a characteristic inherited from its breeding line. New growth emerges with dark reddish-purple tints. The plant is moderately vigorous, building a strong framework over time but occasionally producing blind shoots that require attention. Good basal growth keeps the plant productive.

Climate & Hardiness

Hardy in USDA zones 6 through 9. Blue Moon produces its finest color in cool to moderate climates, where the lilac-blue tones develop fully. In hot climates, blooms may fade to washed-out mauve. It thrives in the maritime conditions of northern Europe, the Pacific Northwest, and coastal areas. Cold hardiness extends to -20C with reliable winter protection. Rain tolerance is moderate; the blooms can ball in prolonged wet weather, and humid conditions increase disease pressure. Ideal conditions are dry, mild summers with cool nights.

Seasonal Care Calendar

Planting & Container Growing

Plant in full sun with excellent air circulation in well-drained, fertile soil at pH 6.0-6.5. Space 60-75 cm apart. Good drainage is essential, as this variety does not tolerate wet feet. Amend soil generously with compost and aged manure. Position where morning sun dries dew quickly from foliage. Mulch with 5-8 cm of organic material. Avoid planting in enclosed, humid microclimates where fungal diseases will be difficult to manage.

Container Growing

'Blue Moon' can be grown in containers, though its tall, upright habit requires a substantial pot. Use a minimum 50-litre container with excellent drainage. Fill with a rich, well-draining mix. Water consistently, keeping the soil evenly moist but never waterlogged. Feed fortnightly with liquid rose fertilizer. The tall stems may need staking in windy locations. Position the container where its fragrance can be enjoyed, such as near a patio seating area. Protect containers in winter in cold zones. Feasibility rating: 3/5.

Seasonal Care & Pruning

Spring: Prune to 25-35 cm, leaving 4-5 strong canes. Apply balanced granular fertilizer and fresh mulch. Begin fungicide program early. Summer: Deadhead after each bloom cycle. Remove blind shoots to redirect energy. Water deeply at the base once or twice weekly. Feed fortnightly. Maintain spray schedule. Autumn: Reduce feeding after mid-August. Remove fallen foliage. Apply potassium-rich feed to harden wood. Winter: Mound soil 15-20 cm in zones 6-7 after the first hard frost. Apply dormant spray. Remove mounding in early spring.

Common Mistakes to Avoid

1. Growing in hot, exposed positions where the lilac color fades to washed-out pink. 2. Neglecting fungicide applications in humid climates, as this variety has moderate disease susceptibility. 3. Expecting a blue flower; Blue Moon is silvery lilac, not blue. 4. Failing to provide adequate nutrition, resulting in weak stems that cannot support the large blooms. 5. Overhead watering, which promotes foliar diseases and causes blooms to ball in wet conditions.

Propagation

'Blue Moon' is commercially propagated by budding onto vigorous rootstock such as Rosa laxa or Dr. Huey. Softwood cuttings taken in early summer have moderate success rates of 35-45%. Own-root plants tend to be significantly less vigorous than budded specimens, a trait common in lilac-flowered roses. Grafting onto strong rootstock is recommended for best results. The variety is no longer under patent, so propagation for personal use is unrestricted. Seed propagation produces highly variable offspring. Difficulty rating: Moderate to difficult.

Diseases & Pests

'Blue Moon' has moderate disease susceptibility, typical of lilac-colored roses. Black spot is the primary concern, requiring preventive fungicide applications in humid climates. Powdery mildew can appear in late summer, particularly during warm days with cool nights. Rust is occasional. The moderate petal substance means botrytis can affect blooms in prolonged wet weather. Aphids are strongly attracted to the fragrant new growth. Thrips may damage buds and reduce bloom quality. Spider mites can develop in hot, dry conditions. Regular monitoring and consistent spray programs are essential for best performance.

Cut Flowers & Exhibition

Blue Moon is one of the supreme cut flower roses, combining elegant form, extraordinary fragrance, and unusual color. Cut when buds show full lilac color but are still in the spiral stage. Harvest in early morning on long stems of 40-50 cm. Strip lower foliage, recut under water, and condition in warm water with floral preservative. A single stem in a bud vase will perfume an entire room. Vase life is 6-8 days with proper care. The silvery lilac color is stunning under artificial light.

Collector & Exhibition Notes

'Blue Moon' remains the definitive exhibition rose in the lilac/blue class. Its classic high-centered form and large bloom size make it a consistent show winner. For exhibition, disbud to one bloom per stem, time cutting for the half-open spiral stage, and protect from rain to prevent petal marking. The variety holds considerable historical collector value as the most successful 'blue' hybrid tea ever bred. It is commercially available but becoming less common in mainstream retail, increasing its appeal to collectors of classic varieties. The Gamble Fragrance Medal adds to its prestige.

Comparison with Similar Roses

Compared to 'Sterling Silver' (its parent), Blue Moon offers dramatically improved vigor, larger blooms, and better garden performance while maintaining comparable fragrance and color. Against 'Charles de Gaulle,' Blue Moon has a lighter, more silvery tone while Charles de Gaulle is a deeper mauve with equally strong fragrance. Versus 'Paradise,' Blue Moon is purer in its lilac coloring without the ruby-red petal edges, though Paradise offers more reliable repeat bloom in warm climates.

Heritage & Conservation

'Blue Moon' is one of the most historically significant hybrid teas of the twentieth century, representing a breakthrough in lilac rose coloring and fragrance. The variety is preserved in major rose collections worldwide, including the Europa-Rosarium in Sangerhausen, Germany. While still commercially available, its presence in mainstream retail has declined, making preservation in heritage collections important. The genetics of Blue Moon have been used extensively in subsequent lilac and lavender rose breeding programs.

Cultural Significance

'Blue Moon' has become a cultural icon beyond the garden, its name evoking romance, mystery, and the pursuit of the impossible dream of a true blue rose. The variety has inspired poetry, music, and literature, and its association with the phrase 'once in a blue moon' has made it a popular gift rose symbolizing rare beauty and devotion. In rose breeding history, it marks the high point of mid-twentieth-century German hybridizing and remains Tantau's most universally recognized creation. The multiple international names reflect its global cultural impact.

Frequently Asked Questions