Don't let a beautiful dwarf bully you!
The plant I need to know how to prune is bird's nest
spruce. - S.K. -
This article can save you the cost of a shrub...
Here is what we do, for you and others who have asked,
S.K.
First the overall, then the details of cutting individual branches.
Dwarf Norway spruces: Bigger than you
expect
We love 'em. Picea abies 'Nidiformis' is called
birdsnest and may be the most popular but 'Repens' and other
varieties are quite similar. All are pruned as described below.
None of them read their catalog descriptions. They often reach a
height of 4' or more, and we've seen them 10' wide and still
growing.
Yet we've also been able to keep them small for decades -- 2'
tall, bed-wide and softly -- at the same time preserving their
soft, irregular shape.
When to prune
We do it by pruning in late summer every two years. We cut
during the second half of the growing season so we can leave the
shrubs alone during their spring growth cycles. We design in part
to feature the plants' beautiful,
soft, bright green new shoots,* so why cut them?
(*Some readers wonder, why all these links?)
Besides, most people who cut in spring end up slowing the
plant's increase in size but not stopping it. Take a look at Prune a
mugo to see an example of how this develops. Dwarf pines
have a similar growth habit and the same creeping tendency when
pruned in spring.
So that we can cut only every other year, we shorten and narrow
the plant by two years' growth each time. Growth rate varies with
the plant and the place so "read" that rate on the plant(s) you're
dealing with. (See photo 9.)
Overall: The shrub
before... 
1. These shrubs, focus of aworkshop, have not yet gotten too
big. That's perfect.
Start cutting in the year a plant reaches the size you want. It
will be just right, then you cut it back and it can grow for two
more years, then you cut it again... At no time in the cycle is it
too big.
2. Here we are, cutting.
(A big thank you to Virginia Bergin who manned the camera to
capture this group while Janet pruned, when Steven was called away
from this session.) It may look like only Janet's cutting but
that's because the clipping's just begun -- the pile of clippings
at the arrow will almost triple in size by the end. People always
start out timid but eventually get their hand in.
...and after
3. Done! Here are the plants after fifteen minutes of
cutting.
(Okay, it's the next morning's photo; it was too dark when we
finished. Those funnel weaver spiders netted them
overnight!)
Otherwise, the shrubs look the same, right? Good! They
should.
However, on second look you should notice there's now more space
between the foreground plant and the curb, and that the back, right
plant is showing a bit of an opening.
4. Here is the foreground plant, with a dashed line
indicating its previous spread -- the mulch it covered has not yet
dried. There is also an arrow pointing out a marker rock Janet set
under the plant before the pruning began. That rock is under the
plant in the first photo, too, but completely hidden under the
branches. We didn't move the rock, only cut the branches
back.
5. Below: "Before" is on the left and "After" on the right,
so you can compare.
6. Look, too, at that plant in the back. It had an ungainly
hump developing. (Arrow.) We removed it.
Now can you tell the plants have been pruned?
For a birdsnest that's crossed the line
Here are other birdsnest spruces that had been allowed to get a
bit too wide so that they were hanging over the walk.
7. Janet's already cut the foreground part of the first
shrub. The arrow points out the clippings taken from that
spot.
8. At each place where the foliage has crossed the line,
she's reaching inside the plant to find a needle-clad branch with a
tip that sits behind the line.
She cuts back to make that point the outer edge. If a branch
that's overhanging has only bare wood within the limit we've set
for the plant, she follows that branch 'way back and cuts it at its
juncture with some other branch that does have room to grow.
Sometimes we cut all the way back to the main trunk.
The nitty gritty of
the cuts
Here is a birdsnest branch and the cuts that you might make.
Like many birdsnest spruces, this one has an annual growth rate
of about three inches.
9. The upper
arrow marks the base of the current year's growth. The lower arrow
marks where growth began two years ago.
How to know? The wood changes color, from light brown in its
first year to darker.
Since the growth rate is 4-6 inches over two years, our goal is
to cut the shrub back by 6 inches. We want graceful fluffy tips but
six inches less on the top and each side.
10. So go for it - clip off that central piece where the
pruners were poised in photo 9, since it extends too
far.
11. Then clip that left side that extends too
far...
12. ...and same for the right side.
13. See that we cut to just outside tiny new tips. They are
there just waiting to jump into growth.
There are many such tips on this plant because each time we
shear the outside we then feel our way around the shrub to find and
remove the oldest, most branched limbs. That allows light to reach
the interior and keep new growth coming. We call the second cutting
'
pat and clip', since patting lets us feel those thick, much-cut
stubs. This whole demonstration branch (photo 9) is one we took out as a
thinning.
14. Done. About 5 inches back from where the tips were when
we started, there is now a soft new tip pointed outward, ready to
be the new leader.
All spruces alike
Perhaps you have a dwarf globe blue spruce (Picea pungens
glauca 'Globosa'), a weeping Norway spruce (Picea
abies 'Pendula'), or a dwarf Serbian spruce (Piea
omorika variety) -- cutting is the same for all of them!
Here is a branch from a Koster blue spruce with
branch-shortening cuts marked. We hope you see that it's the same
as photos 9 - 14.
Try it, and ask again if you have other questions. We improve at
telling how-to only if we hear back from readers, or meet you in
the field as we did for this birdsnest pruning at a recent Garden
by Janet and Steven.
We have seen many people tear out
shrubs
that could be cut back and kept beautiful.
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Why all
these links?
We've received mail asking, "Why all
the links?" and explaining that it takes too long to read "all you
want us to read" now that we're on the website.
Sorry! We don't intend to take up your
time. We send you a summary so you can pick and choose articles,
and try to keep each article as short as possible.
Some of the links we include
("overall" and "details" in this article) are to help you skip
forward in an article to exactly the points you want to read.
Other links we include are there so
any reader -- including us -- can follow up on related or
additional questions.
For instance, in this issue we mention
the birdsnest spruce's beautiful spring greenery. That's point is
the basis for the timing of our pruning but there is no reason to
show the greenery here. Yet we know people ask, "What can
be so pretty about a spruce?" and we have already illustrated its
spring beauty in What's Coming Up 45, so we linked to that
issue.
We don't think you should have to
follow every link, only that you sometimes may want to go deeper on
some item.
We have been writing on the website,
and bringing our whole library here where you can use it, precisely
because we wanted to check what we're writing now against what's
gone before. It helps with our life goal to not write the
same thing twice. However, we do know after 25 years of writing
Q&A that some questions will be repeated. Links help us answer
two questions with one article.