Re: CULT: mulch & rhizome depth
- Subject: Re: CULT: mulch & rhizome depth
- From: L* M*
- Date: Sun, 10 Feb 2002 14:18:14 -0500
BB (doesn't give name or location) posted this on iris-photos as part of
a discussion following a question posted by Donna Lockman. I thought it
was interesting, so am reposting here so folks searching archives can
find it later:
<I've run some, more or less, controlled experiments with mulch and iris
using
compost in one instance and pine bark in another.
In neither instance did
mulch outside the immediate area of the rhizomes
have ill effects on the
plants. Generally speaking, neither did large
pine bark nuggets when placed
indiscriminately in the bed often covering the
rhizomes through migration of
mulch. Jury is still out on covering rhizomes
though. But, some other
pseudoscientific experiments here regarding
planting depth (surface, 1/2 inch
and 1 inch) indicate conventional wisdom
concerning rhizome exposure may be
flawed.
.......
Well, maybe not a myth. My initial purpose was to
determine what planting
depth produced the greatest increase. Short
version of experiment was: I took
3 rhizomes each of 30 different irises and
planted at the mentioned depths.
The 1/2 deep plantings produced the greatest
increase. No rot was observed in
rhizomes planted at the 1/2 inch depth. It gets
pretty wet here rather often
here. Around 55 inches per year. Generally evenly
dispersed every fifth day
through out the year. Used the same plants to
evaluate nitrogen addition so
may have corupted the data some in that way.
Humidity and temperature are considered high by
most people in US.
In some ways plants seem smarter than people. The
have the intrensic ability
to determine what circumstances are best for them
and seek that enviorenment
as best they can. I believe irises paticularly
addept at doing this. If they
need to produce above the soil level, given a
little time, they will if they
don't see a need, they stay about half to 3/4
buried.
Have seen irises buried (accidentally) under 8
inches of soil rise to the
top, survive, grow and increase while others
"properly" planted adjacent to
them contracted rot. As a whole, iris seem so
much tougher than conventional
wisdom suggest. All in all, I suspect a genetic
component to rot
susceptibility when certain environmental
conditions are encountered.
I'm by no means an expert on any iris subject. I
would not recommend my
horticultural practices to anyone. I get so much
misinformation I feel
compelled to test all conventional wisdom. But, I
am going to continue
planting 1/2 inch deep.
Don't know much about cold, we rarely have 3
consecutive nights below
freezing. But, if that slushy snow stuff don't
harm them. Why would dirt?
Push the envelope. Question the conventional.
BB>
I have to agree with all of this. My rhizomes definitely do better with
a layer of soil on top to protect them from the cold. Most are not any
more likely to rot that way than if their backs are exposed. Like BB,
rainfall is >50 inches here. High humidity & heat in summer,
fluctuating temperatures thru the winter & spring, rare snow cover,
annual killer of iris stalk freeze usually scheduled for mid to late
March, often with a follow up killer freeze in April to finish them
off. These freezes seem to initiate more rot than nearly all cultural
care or abuse, mulch or not.
Linda Mann east Tennessee USA zone 7/8
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