Brunnera, also known as Siberian Bugloss, is a popular perennial for shaded gardens. Its appeal comes from heart-shaped, often variegated foliage and delicate sprays of blue, forget-me-not-like flowers in spring. This guide explores effective methods for propagating Brunnera.
Why and When to Propagate Brunnera
Propagating Brunnera offers several advantages. It allows for expanding garden beds, filling new areas, or sharing with others. Propagation also rejuvenates older, established clumps that may have become overcrowded or less vigorous, improving their overall health and flowering.
The most suitable times for propagating Brunnera are periods of mild temperatures and active growth. Early spring, as new foliage emerges, is ideal. The cool, moist conditions support root development and minimize transplant shock. Alternatively, propagate in early fall, after summer heat but before the first hard frost, allowing roots to establish before winter.
Propagating Brunnera by Division
Dividing an established Brunnera is often the most straightforward propagation method. This involves separating a mature clump into smaller, viable sections. Gather tools such as a sturdy garden fork or spade, a sharp knife or trowel, and a watering can.
To lift the plant, gently dig around the entire clump, 6 to 8 inches from its base, encompassing the root ball. Carefully pry the plant from the soil, minimizing root damage. Once lifted, shake off excess soil to expose the crown and roots.
With the root ball exposed, divide the clump into smaller sections. For smaller plants, gently pull the crown apart by hand. For larger or fibrous clumps, use a sharp knife, a small spade, or two garden forks to cut or pry the plant into sections. Each division must have a healthy portion of roots and at least one growth bud or crown.
Prepare new planting sites by amending the soil with organic matter, such as compost, to improve drainage and fertility. Dig holes wide enough for each division’s root spread and deep enough so the crown sits at the original planting level. Place each Brunnera division into its new location, backfill with soil, and gently firm it around the roots to remove air pockets.
After replanting, immediately water the newly divided Brunnera thoroughly. This settles the soil around the roots and provides needed moisture for establishment.
Propagating Brunnera by Seed
Propagating Brunnera from seed is slower than division, typically used for species Brunnera or specific varieties. Seeds can be collected from existing plants after flowering (late spring/early summer) or purchased. Brunnera seeds typically require cold stratification to break dormancy.
Cold stratification mimics natural winter conditions. Mix seeds with a moist medium like sand or vermiculite, place in a sealed plastic bag, and refrigerate for 4 to 8 weeks at 35-40°F (1-4°C). Alternatively, sow seeds outdoors in fall or early winter, allowing natural temperature fluctuations to provide stratification.
After stratification, sow seeds on the surface of a sterile seed-starting mix, gently pressing them into the soil without deep covering, as light aids germination. If starting indoors, maintain 65-70°F (18-21°C) and provide bright, indirect light. Germination can be erratic, taking weeks to months.
Once seedlings emerge and develop their first true leaves, thin them for adequate space. When robust enough (typically 2-4 inches tall with a developed root system), transplant into individual pots or directly into the garden if outdoor conditions are suitable.
Caring for Newly Propagated Brunnera Plants
Consistent watering is important for newly propagated Brunnera, especially during initial establishment. The soil should remain evenly moist, not waterlogged, to encourage healthy root growth. Regular soil moisture checks prevent drying out, which stresses young plants.
Ensure the new planting location provides appropriate light conditions; Brunnera thrives in partial to full shade. Direct, intense afternoon sunlight can scorch delicate foliage. Protecting them from strong winds or extreme temperature fluctuations during their first season also supports successful establishment.
New Brunnera typically show signs of establishment, like new leaf growth, within weeks to a couple of months, depending on conditions and propagation method. Once visibly established and actively growing, a light application of balanced, slow-release granular fertilizer can be beneficial. Avoid fertilizing immediately after planting, as this can burn tender new roots.