Friday, March 18, 2016

For the love of Irises

Springtime means irises and I'm lucky to have many varieties in my garden. Did you know that name iris comes from the Greek work for rainbow.  I have a pluthera of blue/purple, white, and yellow colored iris perennials. Most I've secured free off Craigslist or Freecycle. I have a few unique and native ones I purchased which I'm nurturing. 

It's not a native flower for U.S. gardeners - its originally from Syria. While used in perfumes, medicinals, and even to produce beer and wine, for me it's purely decorative.  I do have some challenges being in a cold climate garden. Not all iris varieties will do well with such a short growing period. 

Want to get inspired by iris? Check to see if there is a local flower show with this theme or try to visit one of the Historic Iris Display Gardens. My closed one in a state away and they have a wonderful end of season "garage sale" which I'm already planning on attending in July. Now that's planning! 

Iris - endless variety

Here are some tips for growing iris in a cold climate garden: 

As Iris bloom in the spring it's best to plant them in July, August or September. This is also the best time to divide and replant iris. Planting at this time gives the roots time to establish before the end of the growing season. Plant iris at least four to six weeks before the first hard freeze or killing frost. Select a location that gets at least 6-8 hours of direct sunlight with good drainage and air circulation. (note there are iris that are water loving and make great additions to a rain garden, so check variety requirements closely) I have mine planted on a sunny slope on the edge of a woodland.  Note that when planting, the rhizome (big root) should not be buried, the top of the rhizome should be exposed slightly on the top of the soil. 

This photo below is one of my favorite iris - it blooms first and is rather short. As such I've placed it at the front of the woodland garden. I enjoy having it peek out in early spring. 

The irises should not dry out during the growing season. If dry spells occur the beds need watering. However, iris are very sensitive to too much water. Excess or standing water can result in rot.

A general rule of thumb is that every three to four years healthy iris will become over crowded and the bloom will decline. At this time, the iris clumps should be thinned. I try to remove the entire clump, refresh the soil in that area, create several divisions and replant the healthiest rhizomes. This is a good mid summer-early fall garden chore.

The shorter growing season in Chicago to achieve maximum growth possible i believe an early fertilization is best.  I don't often have multiple types of fertilizer laying around. I use a general well-balanced fertilizer with an N-P-K ratio of 10-10-10 or 5-10-10.  The American iris Society recommends avoiding fertilizers high in nitrogen as it encourages soft growth which can make the iris susceptible to disease. I apply the first application in early spring and again a month after bloom. I try to place fertilizer around rhizomes, not on them. 

As you might see in the photos from my garden - I plant iris in mass. At times I give attention to creating large beds of the same color. Other times I pop in the odd iris that is off color. It creates an odd note of interest. Just following the lead of the artist Van Gogh in his painting Irises from 1889.

I find that it's important to keep the iris free from fallen leaves and too much mulch to keep the rhizomes from rotting. Prior to application of mulch I cut back the foliage. In the winter some mulch of pine needles helps with soil acidity but I remove it asap in the spring while the ground is still frozen and well before growth starts to appear. Problem with mulching include rodent / insect damage and "mushiness" in spring. This can cause loss of bloom from well developed plants of certain varieties. 

Have fun!

Teresa Marie

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