Do you have a rule, "Keep the garden outdoors, please?" Then
maybe you already know it can be a big mistake to allow
Better to install a sink and counter in the garage, or put
plumbing into a back room. It's worth the cost to keep the gardener
out of the kitchen.
What to do with an iris in winter
As a prime example, Steven had planned to cook a chili the other
night but came home to find the kitchen overtaken by iris
• The no-freeze iris slices
• Firm, fat divisions
• Pests in the refrigerator?!
• (...and extra info because we know you'll ask: Iris planting instruction.)
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No freeze iris
"People asked about the super cold
we had," Janet said. "I'd emailed back about how the snow that
came first was a great insulator, that most perennial crowns had
not even experienced freezing temperatures. Then suddenly I
remembered that I forgot about all the iris clumps we had sitting
in the garage. They were above ground, bare root or nearly so.
Little or no soil insulation there. I had to see if they were still
"And are they?"
"Looks like. See, here's a slice of one of the rhizomes. Firm
and white, it didn't freeze."
Below: No matter how hardy the plant, to freeze is to die.
Super hardy species, including zone 3 (-40°F) bearded iris
(Iris germanica) have ways to keep ice from forming within
their cells. Internal anti-freeze is usually involved yet soil's
insulating qualities play a big part in keeping roots
Soil often remains right around freezing
(32F) even when the air just above is much colder. So when
these bare root iris clumps spent some -17°F time in our unheated
garage, we sliced a few of the rhizomes to determine their fate. We
were pleasantly surprised to find firm, white, tissue (inset
photo). They didn't freeze so they're still alive.
In search of the best iris
"Okay," Steven said, "so you wanted to see if they froze, I get
that. But what's all this mess?"
"Well, there was no sense handling them without cleaning them up
and dividing them so they're ready to go. I'll send a bunch of them
to Diane, now. Get them off our hands. It's nearly spring there in
California, Diane can even put them in the ground
Below, left: The ideal iris division is a husky
Husky, so the plant that grows from that rhizome will bloom
right away -- the growing point on each arm of the Y has enough
substance to produce a flowering stalk.
We look for a "Y" because that plant will be more stable, less
likely to fall over in bloom. Each arm of the Y develops its own
wide root system and like opposing guy wires on a tall antenna or
the outrigger on a Polynesian canoe, each will counterbalance the
Above, right: These divisions made in winter will bloom
shortly after being returned to the ground. That may not allow the
plant enough time to anchor itself with new roots, so they may
require staking. Here, we're using a bent section of clothes hanger
across the "Y."
To avoid the need to stake, follow custom: Divide iris in
summer and put them back into the ground by fall so they have
plenty of time to grow roots before producing that next flowering
How to plant this
iris? Choose a sunny spot with sandy soil that's never
soggy. Scrape out a depression just deep enough that the rhizome
will be barely covered or even have its "back" exposed. Set the
rhizome* in that depression with the root-y surface down. Firm the
soil around or over it. That's it.
If this rhizome had been freshly dug and still had live white
roots, we'd have you dig trenches alongside the depression you make
for the rhizome. Spread the roots into those trenches so they
extend outward and angle down.
Rhizome: What you see here are often called roots or bulbs but
technically they are stems that grow along the ground and develop
roots from the lower side, leaves and flowering stalks from the
upper surface. That kind of stem is called a rhizome.
Right: To make that nice division, we start by breaking up
the iris clump and identifying some husky possibilities. Every
piece of the iris rhizome will grow but we almost always have 'way
more than we need when dividing so we usually discard the tiniest
as well as and the oldest rhizomes. (Old pieces usually don't even
have a leafy shoot.)
Below: Then we look closer, and
use our fingers to test the rhizome's firmness. If there are soft
spots we may yet discard the piece or at least have more to
Rotted portions like the peeled bit you can see below are dead,
probably destroyed by iris soft rot. That's a bacterial disease
that lurks in the soil. (It could as well have been called "stink
rot" for its strong odor.)
Soft rot isn't really virulent but the dead material is
infectious. Even the best grown iris is likely to suffer wounds
that are the bacteria's doorway. Wounds come from cutting tools,
weeders, shovels and above all else, from iris
borers. So we'll cut out all bad portions to reduce the sources
of new infection.
Below: Now we're cutting. We're not done, just stopped to
show you that it's just like cutting the bad spots out of a potato
or an apple. You'll be able to tell what's good and not.
Below: Here's what's left of that piece after the cutting's
done. We've also rinsed and then soaked it for two minutes in water
with a bit of bleach added, because where disease is likely,
disinfecting is a good idea.
In high summer, the customary iris division time, we can
disinfect by leaving the pared division in the hot sun for a day or
Janet's childhood neighbor used the sidestreet sidewalk for this
purpose. She thereby instilled in all the children the knowledge of
when to divide irises... as well as the lesson that you'd better
avoid using that sidewalk during that time as Mrs. Gardner was not
nice if you crunched on of her irises.
"See, Steven? It's not really so different than cleaning
vegetables for dinner!"
"Except eating iris can kill you!"
"Well, yeah, there is that."
"And all that crud over there on the table where you broke the
"Okay, okay, I'll start cleaning up. As soon as I look into
Pesty insect issues
What insects are those? We
don't know, yet. They were
revealed when we peeled the
skin of the moist, rotted
section of one of the rhizomes.
Are they eggs? We don't think
so; probably early-instar*
larvae. Maybe they're
springtails, which are akin to
but are not insects. Or maybe
they are something more
sinister, an iris problem biding
its time until spring.
*Instar: A stage of
development in an insect's life.
This and other nifty words are
explored in our
They are probably not iris borers, which spend the winter as
eggs on foliage and other exposed surfaces. It will be March or
April before iris borer eggs eclose (the insect version of hatching
from an egg).
These critters we found, already 1/8 inch long, look more like
they've been growing for a bit. Perhaps they've even finished early
growth, are pupating and will emerge as an adult as different in
appearance as moth from cocoon.
"I put them in the 'fridge to keep them cold
and let them have the winter to develop into something we might
"They're in the refrigerator?! There's like a
whole drawer full of plant problems already in
there. You said you'd quit."
"But look at them, Steven. We haven't seen
Your Iris borer
So now that you've seen what soft rot does to
iris roots you want to know more about the iris borer? Good,
because keeping that insect in check is the best way to reduce or
even eliminate soft rot from your irises.
What's Coming Up 42 (Yet to be posted -- you can
• Divide in July to control. Never had this trouble? You will!
What's Coming Up 151. Click to open its page and
download the pdf.
• What you'll see and do in July.
Coming Up 154. Click to open its page and download the
• Noticing borer damaged leaves in October; what to do.
What's Coming Up 157. Click to open its page and download
• The iris borer moth
Concerns 59: Click to read
• The borer's life cycle and weak points
Growing Concerns 530:
Click to read
• Why pesticide is not the best control
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