Question
When I bought my house, there was a little patch of light green long leaves growing out of one corner of the yard.  Every year, around April, one - only one - stalk grows out and produces three purple Irises (Elsewhere in the yard is another patch that produces yellow ones).  After the flowers whither, I'm left with a dead stalk and a patch of green leaves with nothing else.  I want to know what to do with this patch. There are tons of tuberous roots, but only one flower ever blooms.  How can I get more to bloom?  What do I do once it finishes - do I cut it down?  What do I do with all the leftover leaves that stick around the rest of the summer - if they are not blooming, I would like to plant something else.  I have planted purple calla lilies right nearby and I would rather that they took over the space.  Thanks so much!

Answer
Hi Rikki,
Thanx for your question.  It sounds to me like your irises need to be thinned out.  I love irises and have a huge patch of them at the side of my house.  Unfortunately, the blooming period for irises is short and they can grow into a crowded mess rather quickly.  They need to be thinned about every three years.  This means digging up the patch, discarded the dead and/or diseased rhizomes (the root is called a rhizome which is a modified underground stem...)and then replanting the irises about 12 inches apart.  You'll find you have a lot of extra rhizomes so, share them with family and friends.  Once you have thinned out your iris patch I'm sure you'll be pleased with the number of iris blooms the next year.  Be sure to sprinkle some bone meal on the patch in the early spring and then maybe again right before they bloom.  After the plants have bloomed, you can cut off the blossom stalks to prevent them from going to seed (which some will) and this drains off energy from the rhizome.  Don't cut back the sword-like leaves until they begin to wither and turn yellow and/or brown in the late summer or early fall.  Why?  The leaves are gathering energy from the sun while they are green.  This energy is stored in the form of sugars and starches the plant manufactures and then it is stored in the rhizomes for next years bloom and growth.

If you don't like the irises and would prefer callas (I assume you live in a warm climate that is mostly frost-free or where the soil doesn't freeze.), dig the iris rhizomes up and give them away or compost them.

I hope this helps.
Tom