Minnesota hardy Arisaema

Jean Halverson jahalve at MHTC.NET
Mon May 19 08:21:44 CEST 1997

I just got back from the North American Rock Garden Society annual meeting in
Minneapolis-St. Paul area where several gardens had non-native Arisaema.  Betty and
David Peterson's garden is on the banks of the Mississippi which might moderate the Zone
4a area some but they had sikkokianum blooming as a ground cover under a small tree.
Beautiful!  The handout said Betty started around 100 from seed, they are now reseeding.

A. taiwanense (I'm not double checking the spelling on any of these names--the gardens
outside are calling!) was blooming but they were new acquisitions.  She has had a bulb
of this species for a few years and had pulled back the mulch and dirt to find a thick
sprout that will be above ground in a few days.

Serratum was also a new acquisition and blooming, but I believe that species is
considered reliably hardy that far north.  She was also growing tortuosum and flavum but
like taiwanense, they were not up yet.

She said she has grown ringens for about 10 years, 3 yrs at this address.  She had 5
plants blooming last year and at this time the spikes were 4-5 inches out of the ground
and not starting to release the leaves or flowers yet.  Impressive.

One tuber of angustatum var peninsulae was up and leafed out but she said the other bulb
4" away had come up a little earlier and succumbed to a late spring cold snap (8 degrees
F for 3 mornings in a row in mid April if I remember correctly the comments from these
gardeners) and the main plant died back to the ground.  It had several small plants
coming up from the tuber or offsets beside the tuber.

Betty had a loose 2-3" mulch over her gardens (the soil seems to be quite neutral in
this area of Minn. and we saw a lot of pine needle mulch of some kind) and like most of
the gardeners here, relied heavily on a winter mulch.  Leaves (or marsh hay in one
garden) piled 6-8" is used to moderate their cold winter temps.  When spring comes,
though, the early plants want to grow and the covering has to be pulled back.  Some
people had suffered through 3 unusual cold snaps after spring growth had started.  On a
local tv news program the anchor asked the weatherman if she could safely put away the
sheets she'd been using to cover plants.  He didn't commit himself.

At Cole Burrell's garden one Arisaema was blooming--beautiful blossom on an unlabelled
plant.  As I was looking for Cole to get an answer, I remarked to Jim McClements (also
on this trip--nice to be able to put faces to names) that at least I knew it wasn't
triphyllum.  He wasn't so sure and was probably right.  Cole thought it was triphyllum
(dark spathe which I also see at home but the lower part was also very dark--triphyllum
coloring is extremely variable) which had lost the tip of the spathe to freeze damage.
The shape of the spathe and the way it was carried so high above the leaves (possibly
also affected by weather) made it look quite different from the plants native to woods
in my area.  Cole had another Arisaema just starting to unfurl it's blossom and he
though it was serratum.

I'll probably still grow my seeds/tubers indoors until they get close to blooming size
just to hasten their growth along but I'm more confident now about using heavy mulch and
a protected site to let more of them experience the great outdoors.  Cole is a plant
collector transplanted from Virginia and he assumes, until proven wrong, that Zone 7
plants might grow for him.

Jean Halverson Zone 5b, sw Wisconsin--most of the triphyllum is up and unfurled, I can't
see any dracontium yet.

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