Decision-making in the Garden: When to Prune and How Much

An overgrown dappled willow in July of 2012,
the middle of a 5 month drought with temperature near 100 degrees (F) each day.

I am hoping for a gardening day today.  Siri tells me partly sunny and 55 degrees (F), but Siri is often wrong about things like where Waseca, MN is (She is really bad with names!  But somehow she knew immediately that Robert Redford was 77 and didn't even attempt to hand me off to some biopic website.  She must be a fan.); or panders to me with innocuous responses like, "That's an interesting question."  Sometimes she responds with esoterica only someone my age would know, a reference to HAL or when asked for news throws something out about Apple.  She is very much Jobs' daughter.  You have to wonder at the involvement of Steve with the code for Siri's personality.

However, hoping for a gardening day, I have several tasks facing me.

My dappled willow, Hakuro Nishiki, has the starts of tiny leaves.
Two weeks ago, before all those little black rain clouds, I had removed about a third of the interior, which was dead.  It left the shrub a strange amoeba-like shape, in a place where my artist eye calls for a sphere.  Now with the start of those leaves, there is a good possibility that some of what I thought might be alive was wishful thinking on my part.

Now the standard rule is to trim back a third of your woody shrubs each year at the appropriate time.  You want to trim shortly after any bloom.  When trimming for shape, you want to keep in mind whether it blooms on new or second year wood. Even, when you really like everything a shrub is doing for you, you want to trim at least a quarter (but no more than a third) of the stems right to the ground.  This encourages the shrub to send up new, juvenile growth, with better form and better bloom.

Sometime we have tougher decisions to make.

Japanese maple 'Bloodgood', spring 2013

For example, I have been patiently trimming my Japanese maple for shape each year.  As small as it was, it was still a bit pricey and I was never quite sure it would survive here in my garden.  Even with moving it, mid-September last year, it survived our brutal winter.  It had, though a major issue with its form.  It branched into a "V" about four inches from the ground. In my mind's eye, ten years from now, I did not want this form in my garden.

Pruning off the one side, took off nearly half of its growth.  I did not want to prune it last growing season.  I wanted it to store up all the energy it could grab with those rust colored leaves.  Anytime you move a plant, you leave some small portion of its root system behind. I figured losing some roots in the move and trimming before active growth, but after sap run would send all the right messages to the plant.  The very act of pruning or wounding a plant promotes growth hormones to travel to the site of the wound.  (This is why pinching phlox is such a good thing and how pruned plants develop a nicer, denser form.)

Early last summer, my smoke bush had not budded out.  I feared it was dead.  I was frantic.  Last summer my garden was on a garden walk and I really needed that plant in that location to screen the view, so the whole of my garden was not viewed in one sweep of the eye.  In giving it time, (and a very stern talking-to each day!), it eventually sent up a few leaves from some of the older branches.  Many of the branches were dead.  Left, it would have a very scraggly shape.  With my heart in my throat, I cut the whole thing to the ground, minimally sacrificing the smoke bloom.  Within a short six weeks, it had sent up dozens of new, strong shoots, each 5-6 feet tall covered with deep burgundy foliage.  The shape was nice.  Its color was gorgeous and it was an eye-catcher for many who walked my garden that day.

Smokebush 'Nordine' in a typical years with older and new growth.  The newer growth is burgundy, but the older greener growth is in the area where the "smoke" of its bloom originates.

Now, with the dappled willow, it seems it too needs the drastic pruning and cool resolve of the experienced gardener's hand to once again rejuvenate it, but it probably not be without that "heart in my throat" thing, where I second-guess myself.