Astilbe propagation is most reliably done through division, ideally in early spring or late fall, by digging up the plant, gently separating the root ball into pieces, and replanting each piece in a new location with well-draining soil.
Here’s a more detailed guide to propagating astilbes:
1. Timing is Key:
- Best time for division: Early spring (before new growth emerges) or late fall (after the plant has died back).
- Why these times? These periods allow the plant to focus its energy on establishing new roots and growth instead of flowering or preparing for dormancy.
2. Digging and Dividing:
- Dig up the plant: Carefully dig around the entire root ball, ensuring you get as much of the roots as possible.
- Prepare the root ball: Gently shake off excess soil to expose the rhizomes (the underground stems from which new plants grow).
- Divide the root ball: Use your hands or a spade to gently pull or cut the root ball into several pieces, ensuring each piece has “eyes” (buds) from which new growth will emerge.
- Consider the size of divisions: You can divide the plant into smaller or larger pieces depending on how many new plants you want to create.
3. Planting the Divisions:
- Choose the right location: Select a location that provides partial to full shade, depending on the specific astilbe variety, and well-draining soil.
- Prepare the planting area: Amend the soil with compost to improve drainage and fertility.
- Plant the divisions: Plant each division at the same depth as the original plant, ensuring the crown (where the roots meet the stem) is just below the soil line.
- Water well: Water the newly planted divisions thoroughly and keep the soil consistently moist, especially during the first few weeks.
- Mulch: Apply a layer of mulch around the plants to help retain moisture and suppress weeds.
4. Seed Propagation (Less Common):
- Astilbe can be grown from seed, but it’s not as reliable as division .
- Seeds can be difficult to germinate: and may not produce plants that are true to the parent plant.
- If you choose to propagate from seed: Start seeds indoors in flats or sow them directly into the garden in late fall or early spring.
- Be patient: Seedlings may take a few years to mature and flower.