California Don has much experience in growing
palms in a temperate climate and provides other valuable contribution.
This time, how to provide heat for those recalcitrant hardy palms. by Don Tollefson, 599 California Avenue,
Venice, California 90291, USA Chamaerops No.27 Summer 1997
Most importantly, I would like to establish the
ideal outdoor planting size for palms as a large, 'substantially'
root bound five gallon (10inch/25cm diameter) pot which should be
planted during the late spring or early summer. 'Substantially'
means that the container can be knocked off the root ball with no
soil falling off the roots, with root mass equal to or exceeding
soil mass. When the container is removed from a 'ready to plant'
palm, the solid mass of entangled roots which has become compressed
inside the container seems almost like a mass of concrete rather
than a root ball. Attaining this condition requires some patience,
but the pay off occurs after the palm is planted in the ground and
explodes with growth during that first year, rather than 'sulking'
(a condition of shock which palms routinely experience whenever
they are planted being less than excessively root bound).
This is the most critical key to success, because
initially the palms can be grown to this size much more quickly
in a controlled environment than outdoors in the ground, and next,
the palms grow much more quickly after planting, so the end result
is a palm that was planted in the ground later, but ends up much
larger and healthier in the same time period. Remember, the race
is not how quickly you plant the palm in the ground, but how large
and how well established the palm is as it prepares to face its
first upcoming winter. Growing palms to this ideal planting size
quickly, requires consistent heat and a controlled environment for
many palms, and moderate heat coupled with ample time for the remainder.
In all instances, the palms require winter protection, and in particular
should never be allowed to experience temperatures that go below
freezing. Many species can endure freezing, but nothing is accomplished
by subjecting them to it unnecessarily, and you can induce 'automatic
shut down' whereby the palm will shut down immediately at the first
sign of cold. Remember, palms have 'memory' and freezing is a drastic
cut off point for palms which they can easily 'remember' and which
they should only be required to endure after they are planted outdoors
in the ground along with whatever protective help you re willing
to provide as a grower.