Growing Multiple Varieties of Iris

If different varieties of iris are planted close together, will each plant continue to stay true to its original form? If not, how far apart should the plants be?

Not to worry, the original plants will stay the same but due to cross pollination, exchange of genetic material between two different varieties of iris, their offspring won’t. You can prevent the problem by deadheading faded flowers preventing seeds from developing or removing the few, if any, unwanted offspring that sprout in the garden. And don’t worry about limiting the growth. These plants increase in size overtime. It is wise to grow equally assertive varieties together so the more timid of the two is not engulfed by the other.