Old fashioned New Zealand flax, Phormium tenax, is becoming increasingly uncommon. It is simply too big for compact modern gardens. Even without upright stems, its vertical and olive drab leaves can reach ten feet tall. They can flare outwardly as wide as fifteen feet. One cultivar is bronzed. Another is variegated. Both are somewhat more compact.

Most modern cultivars are either Phormium colensoi or hybrids of the two species. They are more compact and more colorful. ‘Jack Spratt’ grows only about a foot and a half tall, with chocolaty bronze foliage. ‘Yellow Wave’ gets about three or four feet tall with arching foliage with yellow stripes. Others are bronzed or striped with yellow, brown, red or pink.

New Zealand flax is remarkably resilient. The evergreen foliage is so very fibrous that it can be difficult to cut. Tough rhizomes that migrate where they are not wanted propagate easily by division. Some cultivars can revert by generating less colorful mutant growth. Since it is greener, such growth is more vigorous. It can overwhelm and displace more colorful foliage.