Using irises in the garden

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.

Ming iris

The idea was to contrast the deep blue ‘Midsummer Night’s Dream’ with the yellow ‘Ming’. So far, our plants aren’t exactly cooperating. The two are flowering, but on alternate days.

Ming bearded irisThe plants are still small, with the flowers about a foot above the ground. In time, they should spread into low clumps covered with flowers – and by then hopefully Midsummer Night’s Dream will also be a low clump, so we’ll get a deep blue-violet and bright yellow value contrast with a bit of complimentary contrast thrown in for extra zing.


Planting Irises

Irises are inconvenient. They bloom in spring, but should be planted in fall. With bearded iris, this means ordering after strolling though fields of blooming plants, ordering, and waiting until late August to get your plants and put them in the ground. For native iris, we purchased in spring, planted the pots, then removed the pots in fall.

The native iris strategy did not work as well as it might have. We lost one plant, others are scraping by, one is doing well and another is doing great. Unpredictable. Next time, if we buy in spring, I think I’ll just cut the pots so the plants can grow out of them and put them in the ground, pot and all.

The bearded irises are mostly low growers – about two feet, except one variety that’s in there for height. They’re various shades of blue, with one yellow plant included for contrast. The idea is that they’ll grow in a multi-colored clump for a spot of color in the meadow.

Bearded iris will grow with very little water, so they do blend in with California natives, even if some might be against mixing natives with non-natives. Since this is a garden, not a habitat restoration we’re going for the color and extended blooming season with these plants.

The native iris, all planted at the same time in about the same place, are proving to be variable growers. We don’t know why one plant died. It was probably not lack of water since plants next to it remain green and other nearby irises are growing. One plant grew much faster than the others, even though they’re the same variety (Iris ‘Canyon Snow’). There is a bit of variation in sun exposure, but the plants in more sun seem to be quite happy whereas one in a shadier spot died.

The result of our native iris experiment, so far, is that planting a few more plants than you need, or planting more densely, should help compensate for those plants that prefer death.

The native irises formed seed pods, so if we’re lucky they will re-seed and start to colonize areas of the garden. We won’t know this until the end of next spring at the earliest, however.

The bearded irises are from Horton Iris Garden, about half an hour from here. Our varieties are Ming (1998 – yellow), Codicil (1985 – blue/violet), Midsummer Night’s Dream (1999 – dark blue) and Loreley (1909 – yellow and blue). Yes, those numbers are years and represent when the cross was registered. Irises live a long time!