The Gardenist (the book) started out much bigger than that which was eventually published. We deleted nearly half the word count a few months before pressing the ‘print’ button. Each chapter was nearly as long again with stuff about how to care for each of the plant groups discussed – mostly info I wish someone had told me twenty or so years ago.
One of the bits I was sorry to see go discussed what I consider to be possibly one of the most significant factors by which shrubs can be divided into two groups. The most obvious division in shrubs for temperate climates would be whether they’re evergreen or deciduous, which is little more than an aesthetic consideration. But possibly one of the most useful divisions is whether shrubs are cane-like or peripheral in their growth.
(The other really useful division within shrubs is whether they flower on current season’s, or last season’s wood. But that’ll make a post on its own.)
Yikes. I can see that I’ve now backed myself into a corner of explanation that was never the point of this post.
As for the obligatory explanation: The most obvious shrubs of primarily cane-like growth are roses and hydrangeas. All really strong new growth comes from deep within the shrub – mostly from quite near the ground – and shows itself in long, initially unbranched shoots that head straight upwards, often puncturing right through the existing outline of the shrub. Pruning shrubs of this form usually entails a slow but constant renewal of their fundamental structure by removing old, tired growth right down to where some younger shoot emerges. It’s pruning from the inside, if you like.
This, of course, is entirely different to how you’d prune English box or Viburnum tinus, both example of shrubs that grow almost entirely by extension of the tip. Pruning these shrubs is nearly always about trimming over their outline with hedging shears, or at least cutting them from the outside.
And now for the point I really wanted to make. It was only when I was writing The Gardenist that it occurred to me that almost all evergreens are of peripheral growth. There are very, very few whose growth is cane-like.
(There’s a converse leaning towards cane-like growth amongst deciduous shrubs, but there are far more exceptions)
The only two evergreen shrubs of cane-like growth I could think of at first were the once common-as-muck Abelia grandiflora, and Leycesteria formosa (Himalayan honeysuckle) which is hardly ever seen in gardens any more, but is something of a weed in high rainfall parts of the South-eastern Australia. Later I thought of the semi-evergreen forms of Hypericum like ‘Hidcote’. As I’ve been writing this post, I’ve added the evergreen buddlejas like B. globosa and B. salvifolia. But so far that’s all I can think of.
Can you add any more?
(Just thought of a few more myself: Solanum, Nicotiana glauca, Iochroma. Dang. I’m almost nullifying my own point. Then again, they’re all pretty warm-temperate and frost tender, and the numbers certainly appear to increase with the warmth of the climate of origin)