Leptospermum scoparium 'Wiri Susan'

A compact evergreen shrub that grows to 2m tall and 1.5m wide.

Large single white flowers are produced among green foliage from July to October.

Hardy to most soils and climatic conditions but prefers full sun with free draining soil. It is also frost and drought tolerant once established.

Always choose healthy well-grown plants and plant after autumn rains. Trees and shrubs may be planted at any time throughout the year provided they are watered during dry periods. Planting success is often improved on clay soils by adding extra topsoil and forming raised beds. Incorporate coarse sand, bark, compost or other organic material to improve soil structure especially on poorly drained clay soils. Planting after autumn rains when the soil is moist and warm allows trees and shrubs to become established before winter. This enables them to withstand dry periods during the following summer. Before planting ensure the root ball is saturated and remove the planter bag or pot with minimal root disturbance. Trim any broken roots or branches and plant at the same level as in the container. Dig a hole twice the diameter of the plants roots as soil is placed in the prepared hole tread firmly to bring soil in close contact with the root-ball long term slow release fertilisers may be added at this stage. Mulching will greatly assist in conserving soil moisture and suppress weed growth.

Tall plants and those in windy positions require staking to stabilize the root ball until established. Position the stakes in the hole before planting and place the plant between them. Use wide ties that hold securely without chafing. Tie firmly but allow room for the trunk to increase in girth without constriction. This allows the plant to move a little in the wind, encouraging the development of a strong root system without the risk of chafing or root damage. Unless the soil is very wet water thoroughly making sure that moisture penetrates to the depth of the root-ball.

A general purpose fertiliser can be added at planting time mixed in with surrounding soil and annually in early spring as a side dressing.

Mulching annually will help conserve soil moisture and suppress weeds; organic materials such as sawdust and bark contribute to soil structure as they decompose just be careful to keep mulch away from plant stems.

For lush growth trim back lightly after flowering to promote a bushy habit and prolong the life of the plant. For a natural shape use secateurs instead of hedge clippers. Take care not to prune back into very old wood as plants will not re-grow from this type of material. Except on very fertile soils an annual light dressing (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 surface roots.

The root-ball sometimes dries out despite the surrounding soil being moist; direct water down the plant stem to saturate the root-ball. The first summer and autumn after planting is critical for young plants; water thoroughly during dry periods.

Leptospermum scoparium can be propagated by seed or cuttings cultivars are propagated by cuttings only. The dwarf "Nanum Group' forms sometimes produce vigourous upright growths which should be pruned off.

Attracts a range of insect pollinators.

Manuka are tolerant of practically any conditions but are susceptible to attack by scale insects. These secrete honeydew on which black sooty mould grows detracting from the plants appearance. This can be accepted as a fact of nature or can be controlled by using neem oil.

Prune out badly infected branches. Thrips can also occasionally be a problem. See our leaflet on Pests and Diseases for more information.

TBC

Bred at the Auckland Botanic Gardens.