As gardeners, we often find ourselves in a bit of a predicament. First of all, if we admit it, we want all the flowers. We also like to share our flowers. I would guess that iris are one of the more shared flowers out there. Why? Because iris need to be thinned every few years, so those thinned out iris tend to get shared with willing recipients and some maybe some not so willing. All this to say, if you have iris, there’s a high likelihood they were gifted to you by another gardener. Or maybe they are something you took from your grandparent’s garden as kind of a legacy thing. Either way, a lot of us have iris in our gardens.

One of the benefits of having iris in your landscape is that they are easy to take care of plus they are one of the first flowers to bloom in the spring with those great, big, beautiful flowers. As an added bonus, deer are not particularly fond of these plants so if you have a problem with deer dining on your plants, this is one they will leave alone.

While iris are essentially problem free, they do require thinning every few years. If you have iris in your yard that bloom every spring and they have stopped blooming or perhaps they don’t bloom as much as they used to, odds are it’s time to thin them out.

Iris grow from what is called a rhizome. Rhizomes are like an underground stem and serve as the location where the plant stores its nutrients. These rhizomes grow horizontally and over time they can get overcrowded. When there are too many in too small a space, the competition for nutrients, etc. limits their ability to grow and produce flowers. So, if your iris are getting overcrowded, late July and early August are the best times to thin them out. When we thin them now, they will have all fall and winter to get re-established before next spring. It’s from these thinning sessions that most iris are shared with neighbors and friends.

Master Gardeners (for better or worse) oftentimes become the recipients of these thinned plants because people seem to assume that if they don’t want it anymore, we probably do. In most cases, we already have the plants we want or need, but we’re not about to refuse these strays. So, we either find a place for them or find someone who can find a place for them.

If you have iris that haven’t been thinned in a while, or perhaps never been thinned, to begin the process, trim the iris leaf blades down to about 4 to 6 inches in length. Then you can use a shovel or trowel to dig up the iris rhizomes. A garden fork is also a good tool for this job.

When you’ve dug them all up, begin separating them from one another. During this process, select the rhizomes that look good and healthy and that are about as thick as your thumb. You’ll also want these rhizomes to have at least two leaf blades attached. If they are larger than your thumb or a bit squishy, just move them to the trash.

Once you complete the splitting and selecting process, you can replant them. If you are moving all or some to a new location, know that they will do best in a location that gets full sun in well-drained soil. Be sure to tell whoever you gift any iris to of their location preferences.

When replanting, you only need to dig down 4 or 5 inches. Once you have the location prepared, place the rhizomes on the ground about 18 inches apart. This will give them the ability to grow and spread out. When you cover them back up with soil, the top of the rhizome should be exposed to the air. Once you get them planted, give them a good soaking. Keep them watered just like all your other plants during the year and then get ready to have your blooms come back in the spring. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701 or by emailing us at mg@tulsamastergardeners.org. Photo: Keith Weller, USDA Agricultural Research Service, Bugwood.org