Phormium 'Platt's Black'

Evergreen clump-forming arching shrub growing to 1m tall and 0.7m wide.

This phormium forms clumps of arching bronze-purple purple strappy leaves. Tall stems up to 1 metre tall produce green tinged orange or yellow flowers in spring which are followed by pendulous twisted seed capsules.

Best planted in fertile, dry to normal, free-draining soil in full sun or semi-shade. It will tolerate a wide range of conditions including more moist soils. For best leaf colour plant in full sun. Coastal tolerant as will withstand salt-laden wind and frost hardy.

Always choose healthy well grown plants and plant after autumn rains as the soil is moist and warm and allows plants to become established before winter. This enables them to withstand dry periods during the following summer. Young plants may require thorough watering during dry periods over the first two or three years. Mulching helps to conserve moisture and suppress weeds. Planting success is often improved on clay soils by adding extra topsoil and raising beds. Incorporate coarse sand bark compost or other organic material to improve soil structure.

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 and firm 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 an organic based fertiliser such as blood and bone at a handful per square meter as new growth begins.

Mulching annually helps suppress weeds and conserve moisture. Organic materials such as sawdust and bark contribute to soil structure as they decompose but keep deep mulching material away from the main stems. They benefit from a dressing (50g/m2) of general purpose fertiliser in early spring as new growth begins this will encourage more vigorous healthy growth. Sprinkle evenly and work into the top 2 to 3cm of the soil taking care not to damage surface roots.

The first summer and autumn after planting is critical for young plants; water thoroughly during dry periods. Pests and diseases can have serious debilitating effects on young plants so check regularly.

Phormium are usually easy to grow and require little maintenance. Remove faded, damaged and dead leaves by cutting at the base with a sharp knife. Fans which have reverted from the typical colour should be cut out as these will be more vigorous and over-crowd the rest of the plant. Spent flower heads should also be cut away. New leaf formation and good foliage display will be enhanced by the application of general purpose organic-based fertiliser in spring and autumn.

Rhizomes should be lifted and divided in late autumn. Ensure that each piece split off has part of the rhizome attached with some roots. Each piece can have one or more leaf fans attached. Remove lower leaves and reduce upper leaves in size so the centre leaf remains intact. This forms a triangular-shaped fan for transplanting. Many coloured-leaved forms are not completely stable so poorly coloured inferior fans should be discarded. Replant the selected fans to their original depth in well-drained soil. A stake may be necessary to stabilise plants until new roots have formed.

Flowers of both native species are rich in nectar and therefore are popular with nectar-feeding native birds such as the tui and waxeye.

Too much soil moisture can cause root or crown rot so be sure not to overwater. Mealybugs can be a problem as they can get right down between the leaves at the base of the plant.

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