Pacific Coast irises are also called Californian irises and this gives a clear indication of their native land. Although blooms of a number of Pacific Coast irises have resemblance to those of the present-day Siberian iris and some others may be erroneously considered to be Louisiana iris flowers, you will probably not mistake the flowers of these iris plants for any bearded iris. Pacific Coast or Californian irises readily cross among themselves and, as in the case of several other iris groups, this iris variety has been a subject of interest for the hybridizers. Now there are several iris hybrids, many of them inexplicable, which are commonly known as Pacific Coast irises these days.
One may probably find Californian or Pacific coast iris plants growing naturally on open verdant slopes, on the ground under the mixed forest tress or on semi-shaded hillsides the length of the Pacific Coast stretching from the southern parts of California to Oregon.
One particular Pacific Coast iris species called I. purdyi does not grow higher than a kid's knee. This species is found growing in the wild in redwood forests in the region northwest of California. I. purdyi bears elegant flowers having a creamy-white hue with delicately superimposed falls having reddish-brown veining. The flowers of this iris species growing under the tall, dark conifers, produce a complete and pleasing contrast.
Californian irises comprise 11 species and all of them have a common feature - they are all indigenous to the three Pacific Coast states - Oregon, California and Washington. The chromosome count or 2n of these plants is the same as that of other iris species - having 40 chromosomes. Normally, these iris plants are somewhat dwarf having branchless flowering stalks, narrow grass-like leaves, hard rhizomes and sinewy roots.
However, two iris species belonging to Pacific Coast, namely Iris douglasiana and particularly Iris munzii, are considered to be exceptions. The flowering stems of these two iris species can often grow up to a height of 3 feet (90 cm). In addition to having elongated flower stalks, both these Californian iris species also produce longer as well as broader leaves. Although the flowering stalk of I. munzii is branchless, it often produces as many as four flowers on each spathe. On the other hand, the flower stem of I. douglasiana is branched and has the capacity to produce three flowers on each spathe. When these two species are crossed, the new cultivars have branched flowering stalks and each spathe has as many as four flowers - the total number of flowers on each stem may vary between 8 to 18. Two other species Iris tenax and I. hartwegii are deciduous. Apart from these two species, the other nine Pacific Coast or Californian irises are evergreen.
In fact, most modern day Pacific Coast hybrids have their parentage in two iris species - I. innominata and I. douglasiana. Among all Pacific Coast iris varieties, Iris douglasiana has the most extensive distribution and it grows quickly and without much difficulty from the seeds. The blooms of Pacific Coast irises come in a variety of colors, ranging from white to azure and lavender to purple. In fact, Iris innominata is particularly popular for bearing yellow and golden blooms, which greatly contribute to the beauty of any garden. Indigenous to Oregon, Iris innominata flourishes in cool climatic conditions, but also thrives in other growing conditions. The foliage of this iris species is akin to grass and it makes the plants look finely delicate.
On the other hand, Iris tenax is one Pacific Coast iris species that can endure cold best. This iris species is indigenous to the western part of the Cascade Mountains. Iris tenax has been widely used in various hybridizing programs. This is a deciduous iris species that develops to form striking clumps and bears numerous flowers. Apart from these three iris species - I. douglasiana, I. innominata and I. tenax, which has had a vital role in developing the present day Pacific Coast hybrids, there are a number of other species of this iris variety that have been used in different hybridizing programs. However, those species have played a lesser role in developing the modern Californian or Pacific Coast hybrids grown in numerous gardens, especially in their home land.
Pacific Coast irises are found growing in the wild in the hilly as well as open woodland regions. However, Iris douglasiana is an exceptional Pacific Coast iris species and it is found growing close to the ocean on breezy cliffs and even on open lands, which have been cleared of late. This Pacific Coast iris species is cultivated extensively and is a wonderful garden plant. This iris species will thrive in gritty soils modified by adding compost or some heavy clay soils having an excellent drainage. Iris douglasiana grows very robustly. The leaves of this iris grow up to a length of anything between 12 inches and 40 inches (30 cm to 100 cm) and are about 1/8 inch wide. The color of Iris douglasiana blooms varies from cream to lavender or maybe even reddish-purple. Occasionally, the flowers are also seen in blue and albino hues. Plants of this iris species grow vigorously forming big spherical mats.
The flowers of Pacific Coast irises are similar to those of other iris blooms, having falls that flare instead of curving down or drooping. As far as their colors are concerned, the flowers of different species belonging to this iris class differ much. When grown in gardens, the different species of Pacific Coast irises hybridize among themselves easily, frequently producing attractive progenies.
Irises belonging to the Pacific Coast or Californian class are appropriate for growing in the gardens in the place of their origin. This is mainly because you will hardly find climatic conditions similar to those in the West Coast anywhere else in the United States. In the West Coast, there are places where there is no rainfall for about six months at a stretch.
Pacific Coast irises grow best in gritty soils mixed with lots of organic material and having a pH that is between somewhat acidic and neutral, which suits this variety of irises best. Possibly, Pacific Coast irises will also thrive well in places where the pH of the soil is just a littler higher than 7.0 (neutral). These plants require some protection from the sun during the afternoon. These irises will grow best in places the length of a stream where summers are usually dry and extended and also on moist slopes. When the climatic conditions are warmer, Pacific Coast irises have a preference for shaded to partially shaded locations. A soil rich in humus content and having proper drainage is best for growing this class of irises. Ideally, you should get rid of the old foliage of Pacific Coast iris plants during the fall.
When grown in the garden in the coastal regions, Pacific Coast or Californian irises grow well in full sun. However, gardeners in the interior as well as southern regions, where the climatic conditions are warmer, need to provide the plants with additional shade when the weather becomes hotter. Pacific Coast irises can endure summer water when they are grown in soils having excellent drainage.
Long, arid, warm summers and cool, damp winters are ideal environments for growing Pacific Coast irises. The hot sun coupled with rain will promote crown rot in the plants of this class of irises. When grown in such climatic conditions, the plants are usually lost. The growth cycle of Pacific Coast irises is such that the plants start growing with the arrival of the rainy season and their growth peaks during spring and the early part of summer. In their place of origin, the Pacific Coast iris plants enter a dormant phase once the blooming season of the plants is over and they set seed.
It is best to plant Pacific Coast irises prior to the plants reaching their flowering season and much before they go into their dormant phase during the hot summers. If you divide and transplant the Pacific Coast irises at a time when their growth is vigorous, it means that the plants have robust roots and these roots will help the plants to endure the disturbance due to transplanting them.