Familiy, Origin:Saxifragaceae, Mid and Eastern Asia, North America
Sitelocation:Full sun - partial shade - shade
Garden Height:35 cm,13,78 inch
Natural flowertime:June - August
Crop Time:Plug crop: 9 weeks; Green pots: 10-12 weeks; Flowering pots: 12-14 months with vernalization; Cut flower production: 2-3 years
Seed Form:Raw Seed
Seed Count:16949 K/g
Sowing Method:3-5 seeds per plug
Germination:14-21 days at 22-25 ˇăC, in media with low soluble salt levels and pH: 5.5-6.0. Before sown treat substrate with fungicide. Requires light for germination. Keep soil wet (100 %). Avoid direct sunlight by shading seed after sowing. Use only fresh seeds. When the seeds do not germinate, treat the seeds by cooling for 3-4 weeks at 0-5 ˇăC. Cultivate the following week at 10 ˇăC and later at temperature of 22-25 ˇăC.
Plug Culture:From Stage II* reduce the soil moisture, but the plug should not dry out and reduce the temperature to 18 ˇăC. Do not let soluble salt level rise above 0,75 EC. Start fertilization at 50-75 ppm nitrogen in a well balanced formula. During Stage III and Stage IV fertilization levels can be increased to 150-200 ppm.
Growing On:4-6 weeks after sowing transplant 1 plant per plug tray (3-4 cm) and 6-10 weeks later transplant 1 plant into a pot (10-12 cm), 3 plants into a bigger pot (15-20 cm) or a container (3-5 l). Two time transplantation will support the young plant quality. Plant cut flowers in 30-40 x 40-45 cm space. Position: frost free and partial shade.
Media:Use a well-drained, growing perennial substrate with 10-20 % clay, 0-15 % organic parts (e.g. bark, wood fibres),1-1.5 kg/m3 complete balanced fertilizer, 3-4 kg/m3 slow release fertilizer (3-9 months), iron-chelate, micronutrients, pH: 5.5-6.0. Field: humus soils with good drainage and good nutrition levels. Standard fertilization: 80 g/m2 slow release fertilizer. Sand soils are not suitable.
Photoperiod / Light:Long day plants. For the growth and flowering Astilbe arendsii need high light levels (14 h). Start in spring for the pot plant and cut flower production with supplemental lighting for good plant and stem quality.
Temperature:Grow at 15-18 ˇăC or outdoors. After development of the roots decrease the temperature to 12-15 ˇăC. In winter indoors frost free at 3-5 ˇăC or outdoors. Outdoor fleece cover needed and plants need to be protected against direct sunlight. For the vernalisation 12 weeks at temperature of 5 ˇăC are required. At mid December the plants start to grow for 8-10 weeks at 15-18 ˇăC.
Fertilization:High fertilization levels are required. Fertilize the crop weekly with 150-200 ppm nitrogen (at 3 kg/m3 slow release fertilizer in substrate), using a complete balanced fertilizer. Avoid high ammonium and high nitrogen levels. Don't fertilize after mid September. In spring fertilize 150-200 ppm nitrogen of a potassium balance fertilizer. Prevent magnesium deficiency by applying magnesium sulphate (0,025 %) 1-2 times and in case of iron deficiency (above pH 6.0) apply iron-chelate for 1-2 times. Field: If necessary according to analysis, improve the soil with 60-80 g/m2 fertilizer per year, applied in several portions. N min soil value: approximately 90 g N/m2.
Cut Flowers:Cut flower stems can be harvested, when 95-100 % of the flowers of panicles are open. Put the stems in hot water (50-60 ˇăC) immediately. Vase life: 5-8 days. Cold storage is possible for 3-6 days at 3-6 ˇăC in upright position. If the flowers are not open to 100% at harvest, the buds will wilt and dry in.
Cultural Hints:Do not cultivate the plant too dry or too poor of nutrition. Water and nutrition deficiency cause the buds to deform and dry in.