Forcing Deciduous Trees
Mark W Stephens
markws at one.net
Mon Dec 18 08:41:24 EST 1995
thanks for the detailed reply! Do you know of any books available on growth
habit of trees? I would be very interested in getting one. I noticed that
the Fringtree (chionanthus virginicus) also has a very short extension period,
it was done within 3 weeks in June. This would be very interesting reading.
My sourwood is beginning to break dormancy, but only on one branch. I
currently am giving it ~13 hours of light. I will increase that to 14.
In article <4atrls$767 at jaring.my>, T. Kimmerer <populus at pc.jaring.my> wrote:
>> >Has anyone here had any experience with forcing deciduous trees to
>> >indoors in the winter? I have an extra Oxydendrum arboreum (Sourwood)
>> >aprox. 2 years old, that I am attempting to grow indoors. I have
>> added a
>> >light source that shortens the dark time to about 11 hours, and I
>> have placed
>> >the tree in from of a south facing window. Anyone have any comments
>> >suggestions? Should I fertilize for better results?
>There are two controlling factors in bud dormancy in trees: temperature and
>Short photoperiod commits trees to dormancy, while chilling breaks
>So, you can do one of two things: 1) keep daylength long (>14hr, or give a
middle-of-night light break);
>or 2) once the tree has stopped growing, give it a chilling period. Chilling
periods for buds are not
>cataloged, but those for seeds are cataloged in "Seeds of Woody Plants" by
Young and Young. It turns
>out that the chilling requirements for most seeds are similar to the
requirements for buds of the same
>Note the two complicating factors, here:
>1) daylength and chilling don't substitute for one another,
>they are different kinds of signals. Once short days have committed the
plant to dormancy, only
>chilling can subsitute. So, once your sourwood has become dormant, chilling
is usually required to
>break dormancy. Even this isn't strictly true: some trees can be fooled with
extra long photoperiods or
>2) Sourwood, like many trees, has a fixed growth habit, meaning that the
shoot extension period is very
>short. In Kentucky, shoot growth in sourwood is usually complete by the end
of June, though
>cambial growth continues. In this case, long days may permit a second flush.
>For the hobbyist, the easiest treatment is cold - just leave the trees
outdoors for a month or so, then
>bring them in to force them. I would be very surprised if you could keep
sourwood growing for very long
>without cold periods.
>Fertilizer can stimulate growth, especially if applied after bud set but
before true dormancy ensues. With
>sourwood, you want to be sure to use an acidic fertilizer such as Miracid.
>All this is complicated, isn't it? You will need to experiment for your
particular conditions, because we
>don't really understand all the rules.
>Thomas W. Kimmerer
>University of Kentucky
>Kuala Lumpur, Malaysia
markws at one.net (Mark W Stephens) - Cincinnati, OH Zone 5
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