Thorny Problems

If you claim to know anything about pruning shrubs, then you have probably latched on to a rather simplistic “rule” that goes something like this …

The Rule: Spring-flowering shrubs and woody climbers that flower before midsummer do so on short side shoots produced on growth they made the previous year, so should be cut back after flowering. Those shrubs that flower after midsummer should be pruned in spring and will then go on to flower on the tips of the growth they make that same year.

The problem with The Rule: As rules go, it is useful, and most of us quickly “get it”. But “spring-flowering” describes a rather too vast and varied group to which to apply a single rule, from familiars such as stringy scrambler winter jasmine (January), via dense evergreen ceanothus (May) to gangly but heavenly scented philadelphus (June).

Furthermore, their different growth habits mean that they all need slightly different treatment. There are therefore many exceptions to the rule, so many ifs and buts and “by how much?”s, that the whole thing throws some gardeners into a terminal funk. June and July are tricky months and there is an overlap that causes more anxiety. What about hypericums and ceratostigma, for example, that flower at virtually the same time as philadelphus. Are they spring or summer flowering?

How can you tell the difference? (I don’t wish to digress too much here, but the simple answer is that they are, like Buddleia davidii, technically latesummer performers that flower mainly on current-year shoot tips, as described in the Rule above).

A deeply perplexed reader, Margaret O’Connor, tells me her “gingerly” attempts to prune her 20-year-old philadelphus came to a halt three years ago, when she gave up trying to decide how much to cut it back each summer. She wonders whether to leave it alone and not prune it at all, for the fourth year running, but it is now (unsurprisingly) far too large for her garden.

The solution: taking philadelphus, which needs pruning right now, as an example: One way to minimise the indecision is to sally forth with the loppers/ secateurs the moment the flowers fade, and before the tips of the shoots that have borne them confusingly put on considerable extension growth that would, of course, flower the following year were they not cut back.

We have to ignore these extensions and look further down to find new growth and cut each branch off just above this – which will then, as pruning progresses and the older growth is reduced, become brightly prominent, forming the new outer edge of the bush. Also (crucially, with mature specimens such as Margaret’s), one or two major old stems should be cut right out at ground level, instantly reducing the shrub’s overbearing canopy, while encouraging essential new renewal growth.

There is one problem with the solution: it is not easy to throw yourself into the tangled underworld of a huge shrub on a sunny day in mid-July in order to achieve all this. But, readers, needs must.

Our hard-pressed lockdown grass is now trying to make a swift recovery from the extreme heat. A few points to remember: Do not mow stressed grass too short, as in high summer it is more vulnerable. Leave over-seeding and patch repair until September. Rotaries leave a good finish on small lawns when used to-and-fro (as if vacuuming). If you are a dedicated straight-liner, change direction occasionally to avoid unintentional wheel-track stripes. Keeping a neat edge is less arduous with a ClipperBox (from Amazon, £20.50) attached to your edging shears.