Answer: As you know, glads grow from corms. The corms produce little offsets that eventually mature into corms large enough to support foliage and a flower stalk. When bulbs, corms or rhizomes remain in the same bed for a few years, the strongest hybrids gradually crowd out the weakest hybrids. As a result, you'll end up with a bed full of yellow glads (or purple iris), when you originally planted lots of different colors. The best way to keep this from happening is to dig and replant your corms every year or two, separating the offsets and planting them elsewhere until you know what color they are. Digging will enable you to take inventory every year or two, and to keep only those colors you really like and sharing the others with gardening friends.
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