Along some of my planting areas I have tall dark fences, and learned the hard way that many deciduous shrubs growing adjacent to such a fence will lean away from it, for light I presume. Indeed, so will many perennials. In fact, I have had this problem planting adjacent to the house even on the south side. My plants were leaning away from any structure. When I first started thinking about conifers, it was in part because I noticed that they do not exhibit this tendency, growing straight upwards apparently no matter what the light conditions are. On another forum I was informed that this is because the principle governing conifer growth is geotropism (responding to gravity, basically) rather than phototropism (responding to light). So I have planted my fence and foundations with several conifers, but have already or want to intersperse this with other plants, ranging from broadleafed evergreens such as Osmanthus or Rhododendron to deciduous shrubs such as Japanese maples. My question is whether I am at risk of getting into trouble again with shrubs that lean as I diversify. My observations over the years of various shrubs I have grown or seen in various settings lead me to believe that faster-growing deciduous shrubs may be more likely to exhibit phototropism than those that grow more slowly, but even fairly fast-growing Rhodos seem to grow quite evenly even in one-sided light situations so I wonder if the trait is mostly a deciduous one, since evergreen leaves obviously have to be more adapted to low light conditions, given their persistence through winter. Is there a trick to predicting or understanding which plants exhibit the most and least phototropism?
Sun-loving mugo pines are among those I most often see badly deformed by shading, all the branches pointing to one side as though wind-blown. Even conifers that do point straight up, like dwarf Alberta spruce will instead go bald on the side facing the wall (or window), making them worse actually than leaning broadleaf shrubs. You also do not want to load up on conifers as these are sombre in aspect, having the appearance of absorbing light rather than reflecting it like broadleaf evergreen shrubs do. If you plant mostly in drifts as shown in Grant & Grant, GARDEN DESIGN ILLUSTRATED the leaning of individuals at the back or sides of the drift does not stand out the way it does when each appears as a solitary specimen plant.
Hmm, thank you. Directional pruning didn't work, due to fast seasonal growth and overall not-niceness of the resulting form of muchly-pruned deciduous shrubs. Bald against the fence wouldn't bother me. Don't have room for drifts. Picked up a copy of Grant not long ago at a used book store. Well written, but definitely a book with an agenda - to diversify the use of plant material. As such, useful, but a little dated, since the agenda is well en route to being achieved, and limited in application.