Monday, May 31st, 2010...12:00 am
Mini Iris Problem
Mini Iris by jamesrjohnson
TheGardenLady received this question from Debbie.
My favorite “mini” purple irises have very little blooms this year? Do I need to expose the roots? More sun perhaps?
From the sounds of your letter, your favorite “mini” purple irises have bloomed for you in the past. You don’t mention if the plant seems healthy or not. I hope you checked to see if there is a problem with the plants’ health. If the plants look healthy, then we will make other suggestions.
If the irises bloomed before in the same location they are in now, then the roots were planted at the proper depth. ( You didn’t say if you had moved them to a new location. If you had and they are not blooming, you might have replanted them too deep.)
How many years have you had them in the same spot? Has the location gotten darker because of a tree that might be shading the irises? I find that my irises bloom much more profusely in the sun than in an area where there is shade.
Did you cut the iris leaves after they bloomed last year? You must NEVER cut off any leaves. You must ALWAYS leave the leaves after blooming to enable the plant to build up the energy it needs to bloom the following year. But you should have deadheaded the flowers – cut off the stem where the flowers died so that they don’t set seeds. This is a minor type of pruning and encourages more flowering the next season.
If you have had the irises in one area for a long time, perhaps they have to be divided. One should divide irises every few years or they won’t bloom as profusely. See here.
Even miniature irises have to be divided to get maximum bloom. See here.
Does the location where they are planted have soil that is heavy and wet? If the answer is yes, the bulbs may either rot or slowly weaken over a number of years until they fade away. The only way to have lots of flowers in these conditions is to plant new irises each autumn.
And finally you might consider adding nutrients to the soil. Bone meal is good for irises as is superphosphate and 6-10-10 fertilizer. A light application in the early spring and a second light application about a month after bloom will reward you with good growth and bloom. Avoid using anything high in nitrogen, as nitrogen encourages rot problems. See here.
I hope some of these ideas helped. Good luck.