Phormium tenax – New Zealand flax. Many hybrids have arisen from these species, making phormium a very widely cultivated plant in New Zealand and the rest of the world, much loved because of its hardiness and very architectural habit. These large evergreen perennials are found in scrubby areas, as well as on hillsides and riverbanks, in areas ranging from coastal to mountainous habitats in New Zealand.
The most well-known Phormium tenax is a clump-forming perennial growing op to 4m tall by 2m wide in its native habitat, though more like 2m tall in the UK. It has rigid, upright, linear leaves up to 2-3m long that are dark green above and blue-green beneath. Stout red-purple panicles up to 4m long, of tubular dull red flowers are borne in midsummer.
Once established, Phormium tenax requires very little maintenance, just a tidy up the old lower growth a couple of times a year to keep them looking clean and tidy. A few handfuls of fertiliser around the base in the spring will keep them in good shape and colour.
They take cold winters well, though if a hard winter is forecast, the foliage can be tied up into a pyramid to protect the crown.
Common Name: New Zealand flax
Latin name: Phormium tenax
Tenderness Rating: Hardy down to about -8C though lower if the foliage tied up for the winter, especially if also protected with horticultural fleece if exceptionally cold weather is forecast – in most winters this will not be necessary.
Ease of growing: Easy.
Position: Prefers full sun position, but will also grow well in dappled shade.
Soil Condition: dry to moist, humus rich well drained soil and respond well to a high nitrogen feed in the spring.