False Spirea Astilbe 'Köln' (japonica hybrid)

Water

The false spirea or Astilbe 'Köln' should be kept consistently moist and requires regular watering, especially during dry periods. Aim to water this plant deeply about once a week, providing at least one inch of water to fully saturate the soil. During particularly hot or windy weather, it may be necessary to increase watering frequency to maintain soil moisture, but avoid waterlogging as this can lead to root rot. It is best to water the false spirea in the morning to allow foliage to dry out over the course of the day, reducing the risk of fungal diseases.

Light

False spirea thrives in partial shade to full shade conditions and should be placed in a location where it can be protected from the harsh afternoon sun. The ideal spot is one that receives filtered sunlight or a few hours of morning light, with relief from the hot midday rays. This shade-loving perennial will benefit from the cooler, less intense light typical of a woodland garden setting or a north-facing site in the garden.

Temperature

False spirea prefers a temperature range between 60°F and 75°F for optimal growth, but it can withstand colder winters as well. It can survive in temperatures as low as -20°F, making it suitable for growing in climates with cold winters. However, temperatures above 85°F may stress the plant, especially if it is in a location with direct sun or inadequate moisture.

Pruning

Pruning false spirea is primarily done to remove spent flowers and to tidy up the plant after blooming is finished, usually in late summer or fall. Trimming back the flower stalks will encourage denser growth and can sometimes promote a second, though less profuse, bloom period. Every few years, rejuvenation pruning can be performed in early spring by cutting back the entire plant to ground level to encourage fresh, vigorous growth.

Cleaning

As needed

Soil

False Spirea thrives in a soil mix that is rich in organic matter, moist, and well-draining with a pH range of 6.0 to 8.0. A mix of loamy garden soil, peat moss, and perlite or coarse sand is ideal for maintaining the right balance of moisture and aeration.

Repotting

False Spirea typically needs repotting every 2 to 3 years, as it can become root-bound. The best time to repot is in early spring before the new growth starts.

Humidity & Misting

False Spirea prefers high humidity levels, ideally between 60% to 80%. If the air is too dry, particularly indoors, it may benefit from the use of a humidifier or regular misting.

Suitable locations

• Indoor

  Ensure bright, indirect light and high humidity.

• Outdoor

  Plant in partial shade and keep soil consistently moist.

• Hardiness zone

  4-8 USDA

Life cycle

Astilbe 'Köln,' commonly known as False Goat's Beard, begins its life cycle as a dormant rhizome or crown planted in early spring or fall. Upon sprouting, it develops a clump of fern-like foliage and, as temperatures warm, sends up tall flower plumes that bloom in early to mid-summer with feathery flowers ranging in color from pink to red. After flowering, the plant enters a stage of energy accumulation, where it stores resources in its rhizome for the next season. As temperatures drop in fall, Astilbe 'Köln' enters a period of senescence where above-ground foliage dies back and the plant goes dormant. Throughout winter, the dormant rhizome survives under the soil until favorable growing conditions return. In subsequent years, the plant repeats this cycle, gradually expanding in size and potentially being divided to propagate new plants.

Propogation

• Propogation time

  Early Spring

• The most popular method of propagating Astilbe 'Köln', commonly referred to as False Spirea or False Goat's Beard, is by division. This technique is best performed in the late fall after the plant has finished flowering, or in early spring before new growth begins. To propagate Astilbe by division, carefully dig up the entire plant and gently shake or rinse off the soil to reveal the root structure. Using a sharp knife or spade, divide the clump into smaller sections, ensuring that each section has at least one growth bud and a portion of root attached. Replant the divisions immediately at the same soil depth they were originally growing, spacing them about 18 inches (approximately 45 centimeters) apart to allow ample room for growth. Water the newly planted divisions thoroughly to settle the soil and help establish the plants.