Forcing Deciduous Trees

[Mark W Stephens]

Thomas,

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
>>  grow 
>>  >indoors in the winter?  I have an extra Oxydendrum arboreum (Sourwood)
>>  tree, 
>>  >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
>>  or 
>>  >suggestions?   Should I fertilize for better results?  
>
>There are two controlling factors in bud dormancy in trees: temperature and 
photoperiod.
>Short photoperiod commits trees to dormancy,  while chilling  breaks 
dormancy.  
>
>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
>species.
>
>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
>light breaks.
>
>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.
>
>Good Luck
>Thomas W. Kimmerer
>University of Kentucky
>Kuala Lumpur, Malaysia  
>


{:-)}

markws at one.net (Mark W Stephens) - Cincinnati, OH  Zone 5