Our last post was about enjoying your irises; this article is about how to use them to best effect in your landscape design.
Pacific Coast irises can be a bit fussy if they’re not in their preferred coastal climate, depending on which species were used to breed them. Some species come from the foothills, and are a bit more adaptable inland – although you never know how the plants will fare until you test them in your garden.
Generally, irises do better on mounds if you have heavy soil. If your soil drains well, you can place them anywhere. Rich soil isn’t a necessity, and they seem to thrive in poor, gravelly soils where drainage is excellent.
If you’re lucky enough to live where native California species of iris grow naturally, you can pretty much plant them and forget about them other than enjoying the flowers every spring.
You can divide plants in fall, giving the plants time to re-establish themselves through winter and early spring. If you’re really in a native iris area, they may even reseed.
German iris are stars of spring, but virtually disappear in summer and fall during the dry season. It’s their way of adapting to their native Mediterranean climate – and what makes them so easy to grow in California. This makes using dwarf iris at the front of a border problematic, since the plants will fade away and need to be combined with something that lets the planting area look fuller in the drier seasons. The alternative is to have a spring garden full of a rainbow of irises of all colors and sizes that lives in a corner of the garden and simply goes dormant in summer to await the next season’s rains.
Other irises may or may not be Mediterranean. Dutch iris are bulbs and thrive here. Japanese and Siberian iris need constant water and prefer cool temperatures with higher humidity, so they may suffer through long, hot summers – or guzzle water.
Many species live in shallow water, so forget about using them in water conserving landscapes. One, yellow flag, is considered an invasive species in our waterways, so please don’t plant it in your pond.