Tree ferns are a distinctive feature of New Zealand forest, their umbrellas of fronds standing out against the dense mass of trees. Common in the understorey of native and exotic pine forests, they are some of the first plants that grow in cleared land, especially on damp slopes. They bear their fronds at the top of trunks. Ponga (the silver tree fern, Cyathea dealbata), mamaku or black tree fern (Cyathea medullaris) and whekī (Dicksonia squarrosa) are the three most popular with gardeners. They need shelter from drying winds when young, and grow best in a grove with other trees or tree ferns.
The smaller ferns are usually only grown by specialists. Some hardy species such as hound’s tongue fern (Microsorum pustulatum), scented fern (Paesia scaberula), shore spleenwort (Asplenium obtusatum), and button fern (Pellaea falcata) can be grown in average conditions, and stand some exposure to bright sunlight. Most native ferns require a moist, shaded environment with well-drained, humus-rich soils.
From the northern offshore islands of New Zealand, a number of large-leaved trees, shrubs and climbers were rescued from extinction and brought into cultivation in the nick of time. Browsing animals had reduced them to just a few specimens. In gardens they give a lush, tropical look. They grow well in warmer, frost-free areas of New Zealand.
Tecomanthe speciosa is the pick of the crop: it is a vigorous, woody climber with large, glossy leaves and bunches of tube-shaped cream flowers that appear in winter. The Poor Knights lily (Xeronema callistemon) is another beauty; in summer it sends up flowering stems, with a bottle-brush head of brilliant red flowers. It must have free drainage if it is to flourish.
New Zealand boasts over 65 species of mountain daisies (Celmisia species), including the splendid C. semicordata. This is a rosette plant with stiff, 60-centimetre silvery leaves. Its large daisy flowers have white rays and bright yellow-orange centres. A single mountain daisy cannot fertilise itself, so two or more must be grown together to produce seed. It can be a problem if there is more than one type of mountain daisy in a garden because they cross-breed readily.
The mat-forming Raoulia daisies are easy to grow. The iconic Mt Cook lily (Ranunculus lyallii) is difficult in anything but cool climates. However, southern gardeners who grow it successfully are rewarded with tall stems bearing 10–15 pure white, saucer-sized blooms in early summer.
Many of New Zealand’s rock garden and alpine plants need free drainage to thrive.