Pacific Coast Irises
Pacific Coast Irises (PCI’s) are native to the west coast of America from Seattle to near Mexico. Most are semi-woodland plants that prefer light shade but Iris douglasiana thrives in full sun near the coastline. Iris tenax, douglasiana, innominata and munzii are the most popular and well distributed species in New Zealand and many bright and beautiful new hybrids have been developed from crossing among these species.
Colours range from white, yellow, orange and red-brown through lilac, blue, pink and purple. Many have stripes or darker veining to further extend the colourful picture these irises can make.
Most cultivars are evergreen and form neat clumps. They bloom from late September and throughout October. Their height can range from 20 cm for the little Iris Innominata to 50-60 cm for the new garden hybrids.
PCI’s prefer neutral to acid soil. Good drainage is essential.
An annual dressing of acid fertilizer (depending on your existing soil type) and a handful of sheep pellets is beneficial. In New Zealand’s hot summers it is important to decide on your watering programme. If water restrictions are likely to be a reality it is better to not start watering at all. The PCI plants will usually survive a drought and bounce back after some autumn rain.
PCI’s are easy to hybridize and set seed easily. The pods turn brown and will split and spill their seed in January and February. It is necessary to remove the pods before the split (either to keep the seed or to remove to the rubbish) s the seed will germinate readily around the parent plant.
Plant your freshly harvested seed in general seed mix. It will germinate readily in a shade house or outside as soon as the summer heat departs and autumn rains arrive. Late March or early April is recommended.
Any strong seedlings can be planted out into the garden in spring and they will flower the second spring. Smaller seedlings may require holding over in their pots through the summer until they are strong enough to plant out the following autumn. They will then flower in their third year.
Dividing mature clumps of Pacific Coast Iris can be difficult and there is still debate about the perfect time of year.
Division should be carried out when your clump has developed healthy white roots. The divisions should be of a reasonable good size and the divided pieces should be planted immediately. Keep the plants well watered until established.
This is just a short introduction to Pacific Coast irises. If you would care to learn more about these irises we suggest you join the New Zealand Iris Society, it is not an expensive outlay and you will have much to benefit from.
Written by Mary Barrell
Photo selection by Bill Dijk – Bay of Plenty Group