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Best uses

Excellent in mixed or herbaceous borders, as a ground cover among shrubs, over large rock walls or between boulders. Also does well as a container plant.

Physical characteristics

Vigorous, deciduous perennial that grows to 40cm high and spreads to 1m.

Flowers and foliage

Neat dense green lobed foliage supports bowl-shaped violet-blue flowers with a white centre which are produced from early summer through to autumn.

Preferred site

Grow in any moderately fertile, well-drained soil in full sun or partial shade. Will tolerate darker shade.

Preparation for planting

With suitable preparation and care, perennials will grow and flower well year after year. Young plants are easier to establish than larger ones. They will grow quickly when planted in autumn when soil is moist and warm. On heavy soils, raise the level of beds and borders with extra topsoil and coarse pumice sand. Before planting, ensure the root ball is saturated and remove the planter pot with minimal root disturbance. Trim any broken roots and plant at the same level as in the container. Dig a hole twice the diameter of the root ball, press in and water once planted. Make sure plants are watered well until established if planting in a drier period. Plant with some general slow-release fertiliser and then every spring, apply organic fertiliser at a handful per square metre (e.g. blood and bone).

Planting too closely leads to spindly growth, poor flowering and eventual decline. In a well-planned border, flowering plants should just touch each other to create a full effect without overcrowding. Plant approximately 80cm to 1m apart.

Maintenance tips

Apply mulch annually to suppress weeds and conserve moisture. Organic material, such as sawdust and bark, contribute to soil structure. However, make sure to keep mulch away from plant stems. The first summer and autumn after planting are critical for young plants, so water thoroughly during dry periods. A light application (50g/m2) of general-purpose fertiliser in spring is beneficial. Sprinkle evenly and work into the top 2 to 3cm of the soil, taking care not to damage the delicate roots.

Dividing is a great way to rejuvenate and get more plants. In autumn, large plants can be lifted and divided. This can be achieved by placing two garden forks back-to-back in the middle of the lifted plant and then pushing the clump apart. In some case, the plant may be able to be pulled apart by hand. Plants need to be divided every 2 to 3 years. If they aren't, they will eventually lose vigour and not produce many flowers. Clumps can be separated to around 10cm in diameter if necessary.

Ecological and biodiversity benefits

Attracts bees and butterflies.

Pests and diseases

Ensure plants are well spaced for air circulation to help prevent mildew.

Companion and combination plants

Combine it with grasses sedums astrantias and eryngiums.

Location at Auckland Botanic Gardens

Perennial Garden