Astilbe is a low-maintenance perennial that thrives in cool, moist conditions. The astilbe plant adds a colorful accent to shade gardens as it produces bright plumes up to five feet tall in some varieties. The method of propagation is through dividing the root structure. This will prevent overcrowding and initiate new, healthy growth. The plants can be divided in spring before they bloom or in fall after the growing season has ended.
Dividing the Plant
Choose a planting location that is in partial or full shade. The soil should be slightly acidic at a pH of approximately 6.0.
Add peat moss or compost to the soil two weeks before planting the propagated astilbe. This addition will increase the nutrient level and soil drainage. The organic matter also will assist the plants in retaining moisture during dry weather conditions.
Add sulfur pellets two weeks before planting to increase soil acidity, if needed.
Divide the plants on a day when it will rain. Divided plants will need watering to promote root growth once they are moved. Water the soil around the plant to soften it before digging. Dig around the plant with a spade or trowel to dislodge the root ball. Push the spade underneath the root ball and lift it out of the ground, making sure all the root sections are attached.
Gently pull the root clumps away from the main root crown. Make sure each division of the root and plant is healthy to ensure that it will grow in the new location. Discard the root crown if there is no green shoot growth on it.
Dig a hole in the new planting location that is deep enough to prevent the roots from being bent. Set one to two divided plant sections into the hole so the plants are deeper than in the previous location. Fill the remaining hole with soil and pat firmly around the plants. Water the new plants thoroughly and apply mulch one to two inches in depth. Continue to water as needed.