Hi Muffin,

I'm gonna copy my Gardening with Skybird sheet below, and if you planted them like it says, they should be just fine--by next year if not this year! The part of the rhizome that blooms dies after it finishes blooming, so I don't believe it's possible for them to "get too old." I've has some trouble with mine this year, I think because of the very warm winter, and then with the rapidly changing temps since it got to be "spring!" And the ones that are blooming have way less flowers than in past years, and they're smaller and kind of "battered" looking for the ones that bloom early. The later blooming ones, just starting now, are more normal size and look better, but still fewer blooms, I suspect because of our winter weather for some reason. It's also possible you have later blooming varieties that just haven't started to bloom yet, OR, they might still be in Recovery from being transplanted last year.

Read this and possibly you'll find an answer that I didn't just speculate about!

~~~ Gardening with Skybird ~~~

Planting, digging and dividing German
Iris

German Iris grow from
rhizomes, which are thick, fibrous stems that have roots growing from their
bottom where they’re in contact with the soil.
The “clusters” of foliage that grow at intervals along the rhizomes are
called “fans.” When planting German Iris
the top of the rhizomes MUST be exposed on the surface of the soil—or the
plants may not bloom for you. When
planting rhizomes with established fans on them it’s easy to see which way to
plant them, but if buying just the bare rhizomes in spring, look for the “eyes”
on the rhizome pieces (similar to a potato eye) and plant them with the eyes on
the top side. The rhizomes CAN be
covered (lightly) with a bark/wood mulch after they’re planted without
interfering with their blooming.

Overcrowding is another thing
that can prevent them from blooming, so if you have an old, established patch
of Iris and they’re not blooming, or not blooming well anymore, dig them,
divide them, and replant them with more space between the rhizomes/fans. To do this, when the soil is moist—to make it
easier on both the plants and you—dig the entire clump up and shake off most of
the soil, then take a SHARP knife (or GOOD scissors—you want a “clean” cut) and
cut the rhizomes into small pieces with one or two fans on each piece. Let them lay for a bit—out of direct sun—so the
cut surfaces can “air dry,” and then replant them in either the same location,
but more spaced out, or in a new location.
If the new place isn’t ready, they can be left out of the soil for
several days—put them in a plastic bag that allows for good air circulation and
keep them in either the refrigerator (where they can be kept for weeks) or a
cool, dark place until they can be replanted.
Remember to keep the rhizome exposed on the surface when you replant
them! If you do this you’ll probably be
amazed by how many “pieces” you wind up with to replant, so you’ll have lots
left over to share with friends and family! If you want to get “as many pieces as
possible,” you can also plant pieces of rhizome that have no eyes at all on
them (if they’re at least a couple inches long) and, while they’ll take
“longer” to start growing, they will eventually form eyes and start to grow new
fans just like the pieces that already have fans on them!

When digging/replanting an
established plant cut the fans down to just a few (2-6) inches to make it
easier for the rhizomes to recover and root into the soil well again, and also
to make it easier to keep the fans “standing upright” when you replant them—since
the top of the rhizome is exposed there’s very little “stability” until they
root into the soil.

When digging Iris to
divide/replant them do it VERY early in spring or else wait until they finish
blooming or you may not get any flowers that year. Since they bloom in spring, if you wait till
they’re done blooming you could be getting into hot summer by the time they’re
done, so in that case it might be best to wait till fall to dig and divide them—unless
there’s a reason why you need to do it as soon as possible. If the fans are cut down to a couple inches
Iris rhizomes won’t be as “affected” as other perennials if planted in the heat
of summer.

With German Iris, after a
specific "part" of a rhizome blooms that entire fan and that “part”
of the rhizome will die! If you watch a
plant over the years, the "center" will gradually "die out"
and the new growth and blooms will be toward the "outside" of the
plant—like so many other perennials! By
the time it's finished blooming the main rhizome has grown "longer"
and that's where the fans and flowers for subsequent years will be formed. When cutting dead flowers off of the plant
after it blooms you can cut the entire stem AND that entire fan down to the
ground/rhizome—if you leave it on it will gradually start to brown and look
worse and worse over the summer anyway, so by getting rid of the whole fan you
can keep the plant looking as good as possible for the rest of the summer.

If you just want a couple
pieces of rhizome to give away sometime, gently loosen the soil below some of
the “outside” rhizomes with a shovel or trowel, then cut the rhizomes loose
from the main plant with a sharp knife, and if the soil is wet you should be
able to pull the rhizome with the roots attached out of the soil, leaving the
rest of the rhizomes undisturbed.

© Shawn Dayton 2016

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Hope something in that helps you,

Skybird

Thanks so much!