Winter!
You should admire a tree's graceful sway but never "top
" it
Dear Janet,
In front of my house are two large white pines that are
a few feet from each other. However, the trees are also about 15-20
feet above the corner of the roof. They really sway in the wind,
which is a good thing and part of their charm. But I am concerned
about their height, which is taller than our three-story
house.
Is there a need to cap them -- cut off the tops? Will
this hurt them in any way? Should I prune the dead branches at the
bottom? These trees really bend in the wind and the higher they get
the more concerned I am.
A.S.
Dear A.S.,
Cutting through a trunk or major limb to shorten it -- called
topping -- is one of the surest ways to weaken a tree. Any arborist
worth his or her salt tops a tree only as a last resort.
There is a rot-resistant zone of defense at the base of every
tree limb, where it attaches to a trunk or larger branch. It's
there in the lower limbs of your pines, which probably died in the
trees' own shade. Fungi and insects may now be decomposing that
wood but will be stopped at the point of branch-trunk attachment.
So the trunk is not damaged in the tree's natural shedding
process.
If we cut properly to leave intact the collar at the base of a
limb, the defensive zone is preserved. We can remove even large
limbs yet know that any decay that enters the branch stub will
probably be barred from the trunk. The remainder of the tree will
remain sound.
The barriers to rot are much weaker within the column of wood
that constitutes one trunk or large branch. To cut across a woody
trunk is to open the entire unit to decay that will probably
descend all the way to the base of the tree in a column the width
of the cut.
Healthy wood in a tree is capable of withstanding enormous
pressure. It bends in the wind and under weight of snow or ice,
then rebounds. But decayed wood doesn't bend. It snaps.
A tree of a type that will grow too large for its site can be
kept small by annual pruning. But the time to cut is when the
parts to be pruned are new, before they become woody. Or to cut
every year or two so the tree never develops much wood and weight
beyond the unavoidable topping cuts. The greater the difference
between the tree's natural size and our wishes, and the faster its
growth rate, the bigger the job to keep it small.
Trees are more stable when they have sound wood but a wide,
healthy root system is equally important. We can never declare a
tree absolutely safe from breaking but some are more hazardous than
others. A certified arborist can examine your site, the trees' wood
and roots, and give you the specific recommendation you need. That
may be to remove the trees but certainly not to top them.
Short report
Learn what to do by checking a struggling shamrock's
roots.
E.C. is concerned that a shamrock plant which grew very
well all last summer has been failing since being repotted by a
florist.
Florist's shamrocks (Oxalis) go through a
dormancy each year. That may be what's happening, in which case E.C
should stop watering. A plant without leaves has very low water
needs but can rot from too much moisture.
Whenever a potted plant puzzles us with sudden leaf loss, it's a
good idea to slide the plant out of its pot and inspect the roots.
Root tips can die from cold or the airlessness of water logged
soil. Once dead, they rot.
Rotted roots are as easy to spot as bad vegetables in a crisper
drawer. Firm, light colored roots are normal. Mushy brown tips are
not, so clip them off, let the root ball drain if it's very wet,
then put the plant back in its pot. Move it into very good light,
where the remaining leaves can harness enough solar energy to
repair and replace the lost roots.
If you see only firm root tips and solid tubers like
radishes when you de-pot your shamrock, E.C., then all is still
well. Hold off watering except to keep the soil from going
absolutely dry. Wait for the new growth that will come once the
plant has completed its rest.
Stumper
I enjoy answering questions you mail to me or post on my
school's website. However, some problems have no solution. Don't
expect much help from me if you pose a "stumper" such as: I talk to
my plants all the time while I tend them. Why do they only talk
back, by making their wishes or needs pop into my head, in the
middle of the night or when I'm far away?
Green thumbs up
to this winter's MSU Extension Master Gardener candidates, now
beginning their classes all across the State. When you share what
you learn with others through your required volunteer hours it will
add up to tens of thousands of hours of helping each year. Now
that's truly an "extension" of information!
Green thumbs down
to the search for hardy perennials that bloom all season.
A perennial's nature is to spend part of each year storing energy
for the future, taking a rest from flower production as it does
this. Accept and enjoy perennial gardens for what they do best,
which is to change throughout the growing months, offer contrasts
in plant form and texture, and extend the flowering year into April
and October where annuals can't go.
Originally published 2/12/05