Early summer!
Check non-blooming peonies now to treat those brown
tips and splotchy leaves
Dear Janet,
We are still here with the non-blooming peony
problem.
You came out in 2001 to look at the peony I'd
transplanted that stopped blooming. I don't know if you did
something to the peony but it bloomed the next year. But it didn't
bloom last year and doesn't look like it's going to bloom this
year.
All my other peonies bloom every year.
B.B.
Dear B.B.,
I took photos, leaf samples, a soil test, made notes on the
peony's location and checked its planting depth but I doubt that
influenced its bloom. My visit was to have been part of a quick
look at several peonies to try to identify the reason(s) they
stopped blooming after transplant, with special attention to
whether that old peony bug-a-boo, planting too deep, affects
flowering.
That quick study became a long-term venture. The number of
variables was too great at those original sites. I had to set up
more controlled experiments to test the leads that came from
looking at those first peonies. I can't draw conclusions yet but I
can tell you one thing you can discount and two to look
into.
First, don't worry about planting depth. I saw a range of
planting depths, with no consistent correlation between depth and
blooming. Transplants were blooming with three inches of soil over
the roots yet others under just one inch of soil had no flowers. So
I suspect deep planting does not prevent bloom, except perhaps if a
root is planted many inches too deep. Even there, since next year's
buds form at the base of this year's stems, the plant may adjust
itself to proper depth.
Second, a number of peonies I saw were sited where warm sun will
follow immediately after early morning spring frost. That's a
formula for tip damage, and to lose the tip of a peony shoot is to
lose the flower for the year. Morning shade is better for peony and
other plants sensitive to frost damage. There they thaw gradually
with less chance of cell rupture.
Below: More about the domino effect when peony tips are
killed by frost and then infected by botrytis, in What's Coming Up
88 and What's Coming Up 116.
Most importantly, I saw botrytis, a fungus infection, on all of
the samples. My best guess is that botrytis is the main reason a
transplanted peony doesn't bloom. Weakened by loss of root yet
carrying with it the ubiquitous Botrytis paeoniae fungus spores,
the transplant is prone to infection, especially in frost-damaged
tissue. It loses its tips with their embryonic flowers.
Perhaps your peony bloomed in 2002 because conditions were less
frosty and drier. Tips weren't damaged and fungi didn't spread so
readily.
Check for botrytis infection now, and curtail it. Look for tiny,
brown, dry buds on tips of stems. Clip them off -- they died of
frost damage and/or botrytis and carry contagious spores. Remove
any flowers as they fade, since dying petals are also sites of easy
infection and later contagion. Then keep an eye out all season for
purple splotches on leaves and streaks on stems. Cut all of these
off. Don't worry if that removes big chunks of the plant. Better
that then an infected line on the stem works its way down to the
root, where the fungus spores will rest and reinfect next year's
shoots before they even break the surface.
Do all clipping on dry days when spores are less likely to
spread.
In fall, before the peony dies back on its own, cut it back to
ground level and remove the debris to a hot composting site. Next
spring, treat emerging shoots with a fungicide or an anti-desiccant
to protect them from infection. Cover them on cold nights to
minimize frost damage. Do this for a season or two and the peony
will be able to build up enough energy in its new site to manage on
its own like it did once before..
Short reports
Dogwood didn't bloom, though it has every year until
now?
Many things can affect budset and flower bud retention on a
dogwood. Early freezes in fall, dry winters, and late spring frosts
can kill buds. Loss of a big tree nearby can expose the smaller
tree to frost and drying winds. Maturing trees and new buildings
can reduce sunlight so flowers never form.
When a dependable tree fails to bloom, I look to see if buds set
and then died, which may mean winter weather or a change in
exposure is to blame. If buds didn't form at all, I investigate
growing season differences such as root damage, increased shade or
changes in watering and fertilizing.
Chop those spring perennials now.
I'm about to cut back severely on early daisies, swamp
buttercup, hardy geraniums, columbine and many others that are past
their prime bloom. My reward is fresh new foliage, a neater garden
and, sometimes, more bloom. To improve the health of my garden I
also clip off spent flowers and failed flower buds, which are
potential disease sites.
Green thumbs up
to the dry years that introduced so many people to drought
tolerant plants such as mullein. But thumbs up, also, to a return
to moisture so we can enjoy greater variety.
Green thumbs down
to removing a tree without weighing all the changes that brings
to an area. For instance, removing just one tree on a busy street
can double noise levels that reach homes there.
Originally published 6/26/04