Your
YARD AND GARDEN

Iris and August — a plant junkie's
advice for dividing and multiplying

I am a plant junkie. I see a new plant and I want it. Fortunately, there are many with the same affliction, and we get together often. Unfortunately, we tend to expound on some new plant we found, and then either share it with others or rush out to find one at the local garden center.

David Robson

Now, this isn't a problem for those with acreages that can keep expanding. They are the lucky ones, sort of like those with stretch pants. But like any pair of pants, they can only stretch so much. Then everything spills out.

Which isn't a problem if you have understanding neighbors. Now, this brings me to iris and August.

Siberian iris have to be one of my favorite plants, and a great addition to any garden in the state. Of course, it wasn't in my top five, but that was because there are more worthy plants, which isn't to denigrate Siberian iris in any way. They are worthy. Extremely so. Just not in my top five.

But come August, I see the variety of Siberian iris on the market, and I lose all perspective of space.

A single Siberian iris will blossom into a pretty good sized clump in a couple of years, though you eventually have to thin out the old to encourage the new shoots. The plants are practically carefree. While some other iris (namely the stunning and familiar bearded types) have insects (borers) and disease (rot) problems, the Siberians stand tall. Siberian iris are more grass-like in appearance. Some in my yard are barely a foot high, while others tower at four feet. Flowers tend to be less dramatic than the bearded cousins, but the colors tend to be a little more vivid, as if coated with varnish. And they'll bloom in the shade, though they still prefer full-sun.

Siberian iris, like most of the spring flowering iris, have rhizomes, those thick horizontal stems that should be underground. In the case of iris, though, the rhizomes are at ground level, where they might technically be called stolons, but does it really matter?

Okay, enough about the plants that everyone should put in. The big point is that now is the time to put them in. Iris are best divided, separated and planted in mid-August, right when the temperatures are hitting three digits and the humidity causes you to sweat more than a glass of iced tea.

If you don't separate the plants, eventually you'll get nothing but foliage. In most cases, iris will flower only once from a fan, sort of like blackberries. If you don't remove the old, which really isn't causing any harm other than it's not blooming, and encourage new shoots, you'll have a clump of non-blooming leaves.

Separating the plants is easy. Fortify yourself with plenty of water and plan on working in the dawning hours. Dig up the clump with a good spade or potato fork, and then working with a sharp butcher's knife, divide the clumps into individual pieces. With the bearded iris, you throw away the old fans and save the new ones formed this year. How do you tell? It's difficult and I haven't figured it out 100 percent.

The best method is to get rid of everything in the middle of the clump and keep the plants on the outside. If you plant an old fan, it probably won't bloom next spring, but it will produce baby plants the following year that will flower.

Anything rotted or crawling with insects should be thrown on the compost pile, burned or buried in the next county. Plant the iris in rich, fertile soil that you have supplemented with some compost or other decomposed organic matter. Make sure each iris piece has at least one fan of leaves, a good root system and about 3 to 4 inches of rhizome.

Set the rhizome an inch below the soil. Firm the soil. Water. Drink some water yourself at the same time to prevent heat stroke. With luck, the rhizome will migrate to the surface by next spring, where it won't rot.

The last step is to cut the fans back by half. If you don't, there's a good chance you'll find the leaves collapsed on the soil from wilt. While you probably wouldn't feel happy with half your body removed, it doesn't really harm the iris.

David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, University of Illinois Extension. You can write to Robson in care of Illinois Country Living, P.O. Box 3787, Springfield, IL 62708. Telephone: (217) 782-6515. E-Mail: robsond@mail.aces.uiuc.edu

16 ILLINOIS COUNTRY LIVING AUGUST 2001