Dahlias not resprouting

Uli Urban johannes-ulrich-urban@T-Online.de
Sat, 06 Jun 2009 14:34:00 PDT
Dear All,

Having grown Dahlias for very many years and having tried (and given up)
to establish a collection of species Dahlias I would like to make the
following points:

Dahlis tubers, especially those of the species sometimes to not reprout
in spring, the reason for that is not known. I discussed the matter with
the botanists and gardeners of both Copenhagen and Hamburg botanical
gardens who grow many species Dahlias and who experience the same
 The following reasons are likely:
Virus-Infection: Most species are extremely prone to virus-infections.
These viruses will be transmitted from other plants by aphids and other
insects and garden tools like secateurs.
The "wrong" climate makes them extremely vulnerable for all sorts of
disease. It is a mistake to conclude from the requriements of the common
garden Dahlias which are sun and heat tolerant and must be grown in full
sun in Germany. The species Dahlias come from high elevations in Mexico
and many grow in forests in deep to dappled shade, some grow in full sun
in their cool and most habitat. But even these cannot be grown in hot
summer climates.This explains why Copenhagen is so sucessful with
Dahlias because the summer there is cool and moist.

Of course a stressed plant will be prone to disease.... I had to learn
that the hard way..... My best species Dahlia for almost 20 years is D.
coccinea var palmeri, no sign of disease, an elegant tall plant with
bright orange flowers, best in September.
This explains why Copenhagen is so sucessful with Dahlias because the
summer there is cool and moist.

Another reason for not resprouting is that the tubers may dry in winter
during storage. We have to dig them up in autumn as otherwise they will
freeze in the ground here in Germany. But if kept dry and bare in a
cellar the tubers may shrink too much and especially young tubers or
those of naturally small species will dry out completely and die. I
store them in plastic bags which I leave wide open until the tubers have
dried after lifting and then gently close the bags. No more losses for
that reason any more sice I do that. No rotting either.

Those tubers that do not resprout are always nice and firm and juicy and
will stay like that until even the spring after but will never resprout
and eventually die. Maddening.
The most susceptible to do that are the yellow forms of wild D coccinea,
I almost lost all of them. and D. australis seems to do the same this
spring...... was very nice last summer.

The most valuable ones are grown in pots, even those sometimes do not
resprout...... even more maddening....

There it was, my collection of Dahlias....... was a bit too much work

Maybe this helps to get an idea? British Columbia and the Pacific north
west should be good for that kind of plants as is England, Scotland and

All the best and greetings from Germany....   Uli

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