Mid January: Green thumbs up to a thaw
Arctic cold has just withdrawn, replaced by rain. The clouds
pulled up high and things dried -- except for the snow banks, that
is. Snow kept melting in all directions.
This is a winter thaw.
And this thaw is one of the type we want for winter pruning.
- Mild air temperatures (20's and 30's F) are forecast for two or
- There will be clouds but no rain.
- Nights will be mild, in the 20's F.
Mild temperatures won't freeze exposed wood. The clouds will
prevent precipitous temperature drops at sunset. Dry conditions
help prevent spreading any disease as we prune.
This is all good because the raw ends of cut branches will have
24 hours or more to fill with protective resins before a freeze. In
addition, trees such as maples, birches and beeches that tend to
weep sap after being cut won't do that during winter when there are
no leaves or swelling buds to draw water up from the roots. Even
though sap dripping from branches is not a problem for the trees we
gardeners hate to see our trees "crying."
Also, the gardener will enjoy being out! We wear thermal
underwear, a vest and a coat and quickly shed the coat. We're not
alone. In yards all around, people are out removing holiday lights
and lawn ornaments.
So today was a good day to prune. Tomorrow will be, too. We'll
watch for similar thaws, which often come in late January, late
February and early March.
Winter pruning to reduce a Japanese maple
We pruned a Japanese maple (Acer palmatum) today. (What else could we prune?) It was our third
step in two years in a shape-up and reduction project.
The tree had become too wide and tall -- it blocked access along
the walks and hid rather than decorated the house. Yet the owners
loved the tree's beauty.
1) Make the plan; revise it for Ma Nature!
2) August, begin
3) Then wait
4) The next April, before budbreak
5) August, one year after the first cut
6) January thaw, 17 months after the first
Make the plan
We proposed a gradual cut back:
- First we'd de-clutter the tree and elevate it for pedestrian
- Then over the next year or two we'd shorten main limbs to make
the tree fit the house.
- Once reduced this way and half its former size, the owners
would be able to keep it small with biennial pole-pruning.
An important note: It would have been ideal to begin
pruning when this tree first reached half its current size. (We've
shown you how to do that restriction pruning in other articles,
such as Afraid to cut Japanese
maple. Here, we're dealing with
reduction pruning.) We can't change history or human
nature. What's done was done. Like most gardeners, they were at
first unaware of the need to prune -- aren't Japanese maples
supposed to stay small? -- and then reluctant and even afraid to
cut. Thus the current options: Remove it or cut it hard.
This story began in late summer 30 months ago, when we said,
"Sure, we'll help you cut it back." We have no photo of the tree
then. (Sorry. We're real-life gardeners and don't always foresee
what we should document for reporting.) However, you can see the
initial size in this photo taken one year later, in August moments
before we started pruning. The full spread of the tree is apparent,
although its original density is not.
Ma Nature changes the
We'd planned to start pruning in April of that year but Ma
Nature changed the game plan by cutting the tree back drastically
late spring freeze, the worst in almost 20 years. The tree was
completely defoliated and many branches high in the canopy died
completely -- they were most exposed to wind. We looked at the tree
that April and delayed starting the plan until we could see how
well the tree might recover. Then we'd decide then how much would
be safe to prune.
August. Begin shaping by removing some
That took us to August, when we began pruning. The arrows
(right) point out the most scantily clad upper branches,
where branches as well as foliage died. All leaves there are
growing back from shoots coming right from the main limbs. The
tree's probably only 1/3 as dense as it should be, as it was a year
We said, "Okay, we can prune but we'll go a bit easy." The tree
had put much of its reserve starch into producing all new leaves
and many new branches after the freeze. We didn't want to remove so
much of that new foliage that the tree would have too little energy
to grow back once more, this time from below our cuts.
That day in August we decided on main limbs to keep, identifying
main cuts to accomplish that. Then we cut some but not all of those
limbs. Arrows, above right, mark the parts of the canopy where
limbs have been removed -- compare the two pictures.
The people you see here came to Garden by Janet &
Steven to learn how-to. They looked, questioned, debated
and then cut some limbs and marked others to be cut next time. They
were brave souls! (Left to right above: Cynthia Falska &
husband, Terri Wolf, Nancy & Jim Ranieri, Diane Cotter and
The next step was to wait and see how the tree responded. If it
developed strong new shoots from below the freeze damage and below
our cuts, our next steps would be to work with those shoots as the
start of our smaller new canopy and to cut out all the badly
The next April, before the budbreak
We saw that the tree had managed to put out a good deal of new
growth. The most vigorous shoots (thickest, longest) had sprouted
from wood below the freeze line.
Our next-limbs-to-cut remained marked with rope nooses
(right, inset photo). We decided to take out all the limbs
Here's the result. You may note the tree has not lost much
height yet, only improved in shape while losing width and lower,
walk-blocking limbs. However, note that much of its remaining
height is an upper canopy dominated by dried, brown dead wood.
We'll be cutting those limbs back by half in the next step.
August, one year after the first
We see that the tree continues to grow well from below the
freeze line. We had planned to cut more at this time. However, we
decided to allow all the foliage to remain for the full growing
season, even high up on limbs slated to come out and full of dead
wood (photo below right, brown arrow). The sugars the foliage would
make would help the tree renew the starch reserves it had used to
come back from the freeze and the first hard cut.
Above, left, what we saw a year after the first cuts. Above,
right, what went through our minds. We noted the density
of new shoots coming from below the freeze line (blue arrows
compare a section of trunk in April and August). That freeze line
(dashed line) is going to be our new ultimate height for the tree.
Not only will it be in proportion to the house and no longer block
the door, but it will be less likely to be damaged in future
January thaw, 17 months after the first
We took out all the freeze damaged limbs. This is
the pruning we would have spread over a couple of years if the
original time line had remained valid. Now there was no reason to
wait, as our cuts simply finished what nature started. We removed
wood that was mostly dead twigs supporting weak new growth. In
effect, Ma Nature's freeze led to our cutting the tree back
Right: Here it is, before and after our most recent
It looks bare, we know. Yet based on what we've seen since the
freeze we expect it will leaf out very well from existing buds and
push out a lot of new growth this coming spring. And the owners
will never do what we also avoid: Pruning from a ladder!
We'll post a photo to show you what happens and what comes next.
We expect the tree will grow as just stated, which will signal the
start of every-two-year pruning to restrict the growth (shown most
What's Coming Up 29.). If something different happens,
you'll see it when we do. We'll post the developments here along
with our revised plan.
Much to cut in winter
What else might you prune during a winter thaw? Fruit trees of
all kinds, young shade trees, oaks that can't be cut during
insect-active season for fear of inviting into pruning wounds the
insect-borne fungal diseases called sudden oak death and oak wilt,
and shrubs due for hard cut-back.