Phormium height, spread, & growth rate
Kathy N
Hi, Brian!
Phormium tenax are great architectual plants for a medium to large garden. A mature plant can grown quite large, with many gardeners reporting a spread of up to 5 metres! As a general rule, however, you can expect a height and spread of around 3 metres. Growth rate is average so it will not outgrow a space for a few years at least. If you have the straight species (not a cultivar), I sugggest planting them 2 metres apart. Cultivars tend to be smaller. If so you would have to check the label/this site to see how big they are expected to get. If and when Phormium get too crowded, they can be divided, but you will need a sharp knife as the leaves and root ball are quite tough. From what I have heard of others' experiences with dividing large, established Phormium is to have some help! When dividing, I would recommend cutting back older, dying leaves but would avoid cutting it down to the ground. Some experts say to divide in spring after the soil thaws or warms up, others suggest early autumn which will give the plant time to establish before winter. I would opt for spring. Hope this has been helpful!
Kathy C.
Replied: Monday 29th of December 2008 10:35 PM