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Dahlia imperialis/more info please]

>From: connie hoy <bmprc@micron.net>
>Subject: [Fwd: Re: Dahlia imperialis/more info please]
>Sender: owner-medit-plants@ucdavis.edu
>Date: Wed, 20 Aug 1997 23:23:00 -0700
>
> Hello to Dave and all,
> I twice have purchased a "tuber"of this intriguing plant and am ashamed
> to say I am feeling inadequate to the challenge..First of all the
> "tuber"is actually more like an old piece of wood that has no visible
> eyes whatso ever(nothing like a regular Dahlia).I really dont know if
> there was  life in the first one (it showed rot early on)as it never
> sprouted any growth at all.
>
> The grower sent me a replacement, promising to send more detailed
> instruction but forgot to do so.This one looks slightly more hopeful but
> the one thing he did tell me was that in my climate it would require a
> VERY large container indeed (to winter over).This I can do but not even
> sure as to planting depth ,etc.When I read you had a cutting couldnt
> help but wonder if thats the reccomended/easier method of propagation.
>
> Does anyone know how long the tuber can be maintained without planting
> it?Planting depth?
> Any one that might know the best way to go on this one would be very
> appreciated.
> Regards,
> Connie Hoy

Hi Connie -

What you are mentioning as a 'tuber' I think is actually a length of
stem (i.e. a cutting) - the most common mean by which this Dahlia is
propagated.  The plant does make tubers more typical to other
Dahlias, but quite giant in size, making their shipment somewhat
expensive.  I know this because I once dug out an old clump of these
from an abandoned house scheduled to be bulldozed (It took 4
days!!!)

To propogate Dahlia imperialis from a stem length, place the stem on
its side, buried halfway up.  Keep moist but not soggy, and in
bright shade and out of drying winds.  People often root these
outside under a lightly branched shrub, in a windless corner. (if
your climate is appropriate).  You make also do this in a greenhouse
affair, or a cool window in the house where humidity is not too low.

Can say I've had to learn the finer points of this species
propagation, since they are common in old gardens and there are
often people wishing to remove them to plant something else.  I've
seen 4 clones - the standard single lavender pink, its double form,
the white single, and its double.

Personally, I like the single flowers which are produced in large,
branched clusters, facing down like lampshades.  Big, overblown,
fancy double Dahilas have never appealed to me.  The Double forms of
D. imperialis are interesting and have a decent shape (also smaller
than most Dahlias) but they have the undesireable habit of hanging
on in death, quickly spoiling the display of successively opening
flowers in the highly placed panicles (making it difficult to
dead-head).

I have also never seen seed produced from these plants.  Perhaps
they are self-sterile.

As far as overwintering, it is best for these plants to stay in the
ground over winter - they are too big to manage otherwise and in a
container, flowers would likely be sacrificed.  Ther could possibly
make a marvelous foliage display (almost better than the flowers).
I've had leaves on this plant up to 4ft across, with hundreds of
leaflets (tri-pinnately compound) - just wonderful!  The best
flowering come on plants which can overwinter the tree-like stems
and resprout from these the following spring.

 Sean A. O'Hara                     sean.ohara@ucop.edu
 710 Jean Street                    http://www.dla.ucop.edu/sao
 Oakland, California  94610-1459    h o r t u l u s   a p t u s
 (510) 987-0577                     'a garden suited to its purpose'
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