Originally Published: August 28, 2004 7 a.m.
The tri-city area grows some of the most beautiful iris in the country. They are virtually assured to bloom every spring with little or no care. I am sometimes amazed at the abuse some home owners give their iris, and they still bloom in spectacular colors from pumpkin orange and burgundy red to black purple.
Many gardeners ask for iris in the spring when they are in full bloom. This is not the time to plant iris. What you're getting in spring are the leftovers from last fall's root stock, planted and rooted out by the nurseries. The best time to plant iris is now, through mid-October. The best way to plant them is by root; gardeners call them rhizomes.
An iris root is an ugly thing; you would never expect such beauty out of such an unruly root structure. Like large knotted fingers, these roots know how to run along the ground and choke out weeds, absorb moisture and nutrients, and bloom in a naturally arid climate.
There are a few little secrets I'd like to share with you before heading out to purchase these flowering gems, though.
Here's how to pick a good iris root, and how to best plant them for the flower show next year:
Purchase your iris with the largest possible root or rhizome. This means it was well fed and the blossoms will be of maximum size. Some iris roots are naturally smaller, but the rule of thumb is "bigger is better," at least in this case.
Rhizomes, like bulbs, corms and tubers are simply storage places for food. The more food stored in the rhizome, the happier the plant and the bigger the bloom the following year. You need to feed your iris this year, or you'll have poor blooms the next year. I've had great success with an 11-15-11 granular plant food sprinkled over all my flower beds.
When you get your iris home, trim off the smaller dried root hairs. Prepare the bed by spreading a 2- to 3-inch layer of compost, add 5 pounds of gypsum for every 100 feet of garden and a good all-purpose fertilizer – I recommend an 11-15-11 to my customers here at the garden center. Dig or rototill this mixture of compost, Gypsum and fertilizer to one shovel's depth, or as deep as the tiller will go.
With this formula there is no room for manure of any kind. Manure and bulbs don't mix. There are some bacterial things that happen in soil that cause them to rot in the soil through the cool winter nights to come.
This is the perfect flower bed soil or, in this case, iris bed soil. Use a wide trowel to scoop out a place for your next iris root. Place a small handful of treble super phosphate, 0-45-0, in the bottom of each hole and cover it slightly with soil. Now plant the iris in the hole with about one inch of soil covering the roots.
Roots should be spaced about one foot apart for best show of flower, with the fans facing away from each other. Bearded iris tends to grow in a circle with the center fans dying out with age. If you have an iris bed that has stopped blooming, it could be because of old age and they need to be dug up, separated and the larger, vigorous roots replanted.
It's always a joy to turn an old garden back around into its youthful glory.
After all this, here's what I have found to make the most difference with all your rhizomes and bulbs. Water them every two weeks with Fertilome Root Stimulator, or a similar liquid rooting hormone, until Thanksgiving. The amount of new roots that form on these newly planted iris will astound any gardener, and flowers are sure to follow.
No bulb, and especially iris, likes soggy soil around their roots. Be very careful not to over water these newly planted beds.
Two times a week will be more than sufficient. If you live out in the hard-clay country, once a week may be enough. After Thanksgiving, twice a month watering will do nicely.
You may have been finding large holes in your leaves or nothing but the skeletal remains of a leaf left on your plants. This is the sure sign of grasshoppers. Grasshoppers are a true pest and constant battle if you are the owner of a garden center. Garden centers are a mecca for all forms of bugs, but especially grasshoppers. I'm convinced it's a conspiracy by grasshoppers to swarm in formation to eat my inventory.
I have learned a few effective techniques for keeping these pesky little eating machines at bay. The first is an all-natural product that is highly effective when grasshoppers are small in size (about an inch long or smaller): NOLO bait. This is a wheat-based product that grasshoppers are attracted to that is laced with a bacteria that is deadly to grasshoppers and crickets. Ladybugs, birds and pets are not affected, only grasshoppers and crickets.
The beauty of NOLO bait is that it causes this pest to stop eating immediately and, when digested, affects the eggs that are laid for next spring's hatch. If you haven't put this bait down yet, you should. It won't be quite as effective as its use in June, but it will knock back the numbers for you next year.
If grasshoppers are chewing down your garden, and help is needed immediately, there is only one choice, Carbaryl, or the common name of Sevin. It comes in a powder or liquid form and is applied on the foliage of the plant.
The next grasshopper to come by and munch on this plant will ingest some leaf, and some Sevin. When this happens you are sure to have an immediate kill.
When applying Sevin, I like to use the liquid application. Liquids are easier to apply and stick to the plant better than powders, thereby increasing your kill rate. Try to time this bug killer so you don't see rain for 24 hours.
Whenever you have questions with a plant problem, or wonder what something is out in the yard, take it to your local garden center for proper identification. It's impossible to diagnose garden problems over the phone, but with a leaf or twig from the victim, we can identify many things.
Remember, garden centers become jumpy when exposed disease samples come into a nursery setting. We don't want to infect the healthy plants here on the floor.
Place your sample in a zip-lock bag or jar, and the staff will appreciate you more.
Until next week, I'll see you in the garden center.
Ken Lain is the owner of Watters Home and Garden Center and is an Arizona Certified Nursery Professional and Master Gardener.