Salvia 'Indigo Spires'

An evergreen perennial with a bushy habit that grows to around 1m in height and 1m in width.

Small dark blue flowers are produced on tall blue stemmed racemes over a long period from late spring through to autumn. Foliage is pale green and narrow. Flowers are held well above the foliage.

Plant in full sun to light shade with moist but well-drained soil. It is fairly drought tolerant but will bloom best if watered during dry spells. Can tolerate only light frosts.

Prepare the planting site when soil is moist and easily worked after the first rains in autumn. This way the soil is still warm so the plants can make root growth before the following summer. Always choose healthy well-grown plants. Remove all perennial weeds and incorporate bark compost or other organic material. On heavy soils raise the level of beds and borders with extra topsoil and coarse pumice sand. Plant when the soil is moist and warm in autumn or early spring so that a good root system develops to support vigorous new growth. Before planting ensure the root ball is saturated and remove the planter bag or 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 put in the plant and firm around the base water in well.

With suitable preparation and care, perennials will grow and flower well year after year. They benefit from a weed-free well-drained soil rich in organic material. Planting too closely leads to spindly growth, poor flowering and eventual decline. In a well planned border, the plants in flower should just touch each other to create a full effect without overcrowding. Apply an organic based fertiliser such as blood & bone at a handful per square metre in spring as new growth begins. Control slugs and snails to prevent damage to tender young shoots. Stake plants at or near planting time to ensure the plants are not damaged and grow around the stakes to conceal them.

Apply mulch annually this will help suppress weeds and conserve moisture. Feed annually in spring with a balanced fertilizer such as blood and bone at a handful per square metre in spring as new growth begins. Water during dry summer periods to prolong flowering. As shoots begin to grow in spring stake those plants which will need support. Four or five bamboo stakes pushed into the ground in a circle around the clump with string tied between them should be hidden by the foliage at flowering time. Alternatively, push four stakes in the ground around the plants either in a square or rectangle. Square netting can then be tightened over the stakes and the plants will grow through. Another layer of netting can be added as the plants grow.

In autumn or spring softwood cuttings can be taken as the older plants get the woodier they become so replacing plants every couple of years is advised.

Most salvias require well-drained soil and are ideally suited to growing in semi-shade in Auckland gardens. Occasional irrigation during prolonged dry periods would be beneficial. The majority will not tolerate cold wet soils in winter.

This salvia should be pruned to a quarter of its original height after flowering or in spring in the cooler frost prone areas. Minimal deadheading is required to keep this salvia blooming.

Attract bees and butterflies as well as nectar-feeding birds as this salvia is a major source of nectar.

Infrequent but can get spider mite, whitefly and aphids.

Perennial Garden