Expert: Kenneth Joergensen - 7/18/2005

Question
I bought a home in 2001 that came with numberous plants. One of my favorites were the irises. They bloomed that first year but haven't since. Every year the green leaves come up but there are no blooms with them. They are currently planted beside my garage in an area that is shaded and fairly well drained. However, when I water my hastas, the area does get quite wet. Any ideas or pointers would be greatly appreciated. Thanks!

Answer
Iris normally require a fair amount of sun to bloom, however, since they did bloom, I suspect they just need to be divided and fertilized.

Start by digging the clump. Iris grow offsets (new plants) out in a star shape from the main iris plan. The iris clump is a large rhizome from where baby rhizomes (offsets) develop. As they grow, the middle part becomes brown and dead and to ensure proper blooming, you need to dig them, cut off the new rhizomes and re-plant these offsets. The main center part is then discarded. Do this NOW.

I have a website mainly dedicated to lilies, but I have posted some Iris rhizome pictures which you may take a look at. Especially take a look at picture 1 which show how the main rhizome is developping side shots. As they grow (usually 2-3 years) they can be cut off from the center (mother) and replanted on their own (picture 2). Picture 3 show a very small offset (baby) developing. Picture 4 show the offsets replanted.

Here is the link:
http://photobucket.com/albums/v311/lilium/iris%20division/?sc=6

Also, fertilize your lilies 2-3 times: once in early spring as new growth happens. Once more when they bloom, and again in mid summer.

Good drainage, sunshine and fertilizer are needed for adequate bloom. So is regular (every 2-3 years) divisions. You can also try to google "dividing tall bearded iris" and look as some of the drawings accordingly.

-- Kenneth