I have some irises which have been transplanted several times over 20 years. The foliage is lush but the flowers are fewer each year. Do I divide them? Toss them? Fertilize them? (I prefer natural fertilizers). They are in a garden which gets plenty of sun in the early spring, just a little shade. Not sure what to do next. Thanks! Also, I have been leaving the foliage to nourish the tubers and I usually cut it all off in the fall as it starts to yellow. Is that what you do?
I leave the leaves till they die.
It sounds like you should dig them up (when the leaves die back), divide them. fertilize the bed and replant them.
Bone meal is great for bulbs and tuber type flowers.
http://www.walking-p-bar.com/shopsite/Planting-and-Garden...
I googled iris and found this page.
Mine need to be dug up and separated every few years. I DO feed them, Peter's, but only once in the spring.
:)
Dig them up and divide them. That may help. You're doing the right thing with the foliage. And when all else fails, if my plants displease me, I throw them away (that'll show 'em).
I don't fertilize my bulbs, mostly because I'm just not that motivated to do so. Ask at a good local nursery, or call your local Master Gardener group, and they'll be able to give you advice on that.
Generally, this is because of too much shade (even through the remainder of summer, they are storing energy in their rhizomes for a good bloom the next year). But crowded roots and fertilizing with too much nitrogen can also limit bloom production. Be sure any fertilizer you use is higher in phophorus and potassium than nitrogen. And don't over-fertilize. Irises generally do well with only one light application in the spring.
It doesn't hurt a healthy plant to remove yellowing foliage. Those leaves are no longer producing much food for the plant.
Is it possible they are buried too deep? The tuber should be slightly exposed. Dividing them will spur growth as well.
