Irises are just coming into flower and can be grown in wet or dry spots, says Gillian Vine.
I've never met an iris I didn't like. That even includes the weedy stinking iris (I. foetidissima), whose red berries hold over winter, and to my mind are a great deal more attractive than the plant's dull khaki flowers.
Yellow-flowered I. pseudacorus is another considered a weed and is on the National Pest Plant Accord list as a plant not to be propagated or sold, because the plants spread very rapidly in boggy ground.
Although the variegated form is still acceptable, I confess a preference for the common one although, obedient gardener that I am, I no longer grow it.
These two are rhizomatous species, with shoots appearing along the length of the underground root. Pieces cut off will grow if there is a shoot, no matter how tiny.
In all, there are some 300 species of iris and thousands of named varieties.
Iris may be rhizomatous or bulbous and the former include the popular bearded irises, whose rhizomes lie along the ground.
They love to be baked in summer, which is why they grow so well in Central Otago.
With a great range of sizes, from the tiny miniature dwarf varieties to tall cultivars with flower stems 1m or more, the bearded are the most widely grown.
I. germanica is assumed to be a parent of most modern varieties, which is why they are sometimes called German irises.
All irises have flowers with three upright petals (standards) and three that hang down (falls), although occasionally four-petalled variants appear.
The four-petalled I. reticulata on this page popped up in my garden this winter and I have a dwarf bearded that occasionally produces blooms with an extra petal.
Bearded types are named for the group of fuzzy hairs at the top of the falls and a bright orange beard is clearly seen in the photo of Froufroutant.
The iris clan comes in almost every shade except red. Usually the falls are darker than the standards but are termed reverse where the opposite occurs.
Flowers may be ''self'', which means the standards and falls are the same colour; bicoloured, where there are two colours; plicata with dark lines or stitching on the margins against a pale background; or show contrasting veins.
Bearded irises bloom in spring and early summer but before then, vigorous little bulbous I. reticulata has made its cheery late winter appearance with its blue, purple or occasionally white flowers. They are ideal for pot culture, as is the related species, I. danfordiae.
It has yellow flowers and is quite delightful but I find it difficult to maintain flowering-sized bulbs.
Each bigger bulb seems to shatter into lots of tiny ones after flowering and they require nursing for a couple of seasons to get to flowering size, when the cycle starts again.
Strong-stemmed Dutch, Spanish and English types (the xiphium group) flower in succession from early spring and are among the best for cutting.
They are understandably popular with florists, who sell mainly blue and white varieties, but bulb companies offer yellow, purple, brown and many bicolours, so the gardener has many to choose from.
Most iris cultivation advice concentrates on bearded types but, as well as being rhizomatous or bulbous, they vary considerably in their growing needs, although - almost without exception - they are greedy plants and need annual applications of fertiliser.
Now is the time to do so but leave dividing rhizomatous clumps until flowering has finished and don't lift bulbs until autumn.
Bearded irises appreciate a dressing of lime to maintain pH of 6.0 to 7.0. Wet soil rots them, unlike Japanese I. ensata and I. laevigata, which need damp feet and sunshine on their heads, so are good for the edges of ponds, while the Evansia group can be grown under trees in a woodland garden.
They need a slightly acid soil (a pH of 5.0 to 5.5) and should never be given lime.
As long as the soil is well-drained, bulbous irises are fairly tolerant, growing happily in soils whose pH may be between 5.0 and 7.5.
Little ones, like the reticulatas, are best grown along the edge of paths, in a rockery or in pots, so they can be appreciated at a time when there is little colour in the garden.
Pots have the added advantage of being able to be moved when flowering is over, the bulbs left to mature until autumn when they are repotted.
Choosing different irises gives a flowering time from June or July through to Christmas, an excellent reason for growing plants named after the Greek goddess of the rainbow.
