|I bought iris corms in the fall of 1996 and planted them variously in full to partial sun. In 1997 all of the plants bloomed; last year none of them did. The tops of the corms are barely covered (some show at the soil line). I've fertilized them with a low nitrogen compound, but that won't show results until spring. The plants seem ok -- they're showing new leaf growth already. What else should I do? What do I need to do before I buy more iris to prevent the problem in the future?
|Iris may stop blooming if they've become overcrowded, if their leaves were cut back too early, or if they've been overfertilized. If your iris refuse to bloom this year, wait until August, then dig and divide them. Dig each clump, cut the roots and the fan of leaves to about six inches, then divide the rhizomes by cutting off both ends and discarding the old center. Iris rhizomes grow vertically and only the new growth will produce a flowering stem. After dividing the rhizomes, replant them in a freshly prepared bed into which you've worked several inches of organic matter. Plant so the rhizomes are barely covered with soil, then water them in well. By the following summer your iris should produce blooms.|