Irises are easy, hardy perennials that thrive under difficult conditions and seldom cause much trouble.
Far more than that, they present you in May and June with an all-out blooming spree that makes everything else took pale by comparison.
Here are the methods I use to get irises off to a good start.
They have been proven effective on the more than 500 types of Iris growing in my garden.
Plant High-Quality Iris Bulbs
- Start with good quality stock.
- Choose a good variety.
In iris catalogs, the kinds that have won Dykes Medals or Awards of Merit from the American Iris Society are usually marked.
You can’t go wrong with any of these varieties.
The stock you buy from any of the large companies that specialize in the iris is almost sure to be top quality, vigorous and clean.
Plant The Iris Bulbs In A Sunny Location
At least a half-day of full sun is essential for good iris bloom.
When you plant, do the following steps:
- Dig a sizeable shallow hole
- Draw up a hump of soil in the middle.
- Set the iris root (called a rhizome) on top of the ridge.
- Let the roots run down on both sides.
- Pull soil over them and tamp the rhizome down with your foot.
- In light sandy soil, leave the top of the rhizome a ½” inch below the surface.
- In heavy soil, put the top of the rhizome right at the surface.
- Water after planting.
Provide Good Drainage
To avoid future problems, provide your iris with good drainage.
A site that slopes or a raised bed will help in locations where drainage is poor.
And see that iris soil is neutral or only slightly acidic soil (with a pH of 6.5 to 7.0).
Use Good Fertilizers
For top-quality, exhibition-size blooms, you can use several good fertilizers.
At planting time, I usually sprinkle a handful of bone meal into the bottom of the planting hole below the roots.
Every third or fourth year, I use an organic fertilizer like Milorganite in a ring around each clump.
Don’t let the fertilizer touch the rhizome.
Once the iris is established and growing, I sprinkle a handful of 5-10-10 fertilizer around each clump in the fall.
In the spring, I prefer to use superphosphate in the same way.
Watch For Iris Borers And Other Insect Troubles
You can avoid many problems by cutting away the browned and decaying foliage and removing weeds and debris in the fall and early spring when new growth starts.
In some parts of the country, the iris may be bothered by iris borers, which hatch from tiny eggs laid on the foliage or stems in the vicinity.
Early signs that these pests are present are:
- A puncture in the leaf
- Water running down the blade
- Wet spots on foliage for no evident reason.
Control borers by dusting or spraying clumps with 50% percent DDT wettable powder dissolved in water.
Examples of these include:
- Spinosad
- Permethrin
- Acephate
Repeat applications at 7 to 10-day intervals, especially if rainy weather washes away the original application.
Watch For Disease Problems
Iris are sometimes affected by diseases like soil bacteria, which cause soft rot in the root.
You see symptoms of it when foliage collapses and the base of the plant develops a smelly slime.
If this happens, do the following tips:
- Scrape out the soft part of the root and leave it exposed to the sun’s rays for a day. This will often dry it up.
- If this does not do the trick, pour a small amount of bleach, like Clorox, directly on the affected part of the rhizome. This may delay that root from sending up blooms until the following year.
Other reasons for soft spots may be pulling away foliage too vigorously or digging up rhizomes to give away.
Whenever you leave an open gash on an iris root, It’s a good practice to remember these tips:
- Resist the impulse to replant it immediately.
- Let it lie in the sun for 5 or 6 hours to callus over instead.
- Treat it with a dusting of sulfur before replanting.
Otherwise, the untreated scar may be a weak spot where bacteria can enter.
Leaf spots may attack iris leaves in wet seasons.
These are tan or brown spots that disfigure the foliage but are rarely fatal.
Control these signs by:
- Cutting off the affected parts of leaves
- Spraying the rest with zineb.