How do I go about pruning Ceanothus?
My impression is that in general, Ceanothus should be pruned with a light touch. Portland gardening expert Ketzel Levine has some opinions on this topic:
“You can certainly prune Ceanothus but there is a bit of a trick. First of all never prune any stems that are larger than 1/4″ wide. Instead prune the very tips of each branch back to where you want it to be. And, since ceanothus bloom on ‘new’ wood, this should provide you with an even more spectacular show next year. Prune after the plants are through flowering; at that time you can also remove the spent flower spikes which will also help it look less wild.”
Ceanothus by David Fross and Dieter Wilken (Timber Press, 2006) says that “an annual trimming of the new growth will maintain a more compact form and improve the appearance of most species. The removal of spent flowers and fruit improves the vigor of many cultivars and will produce a tidier form. Taller species can be trained into small trees with early pruning, and the removal of interior dead wood as plants age produces a cleaner appearance. Once the arborescent character is achieved it is easily maintained and requires minimal effort. Shearing for hedges and formal effect is tolerated by most species if cutting into woody tissue is avoided. Prune immediately after flowering, and only back to the new year’s flush of growth.” The authors mention that although it requires a lot of work, there are some species which can also be trained as small hedges or as trellis plants.
Here is the Royal Horticultural Society’s guidance on pruning evergreen Ceanothus species: “Routine pruning is not essential and in fact are best not pruned. If grown as a bush, promote branching by pinch-pruning the soft tips on young plants in spring. Use secateurs to shorten over-long branches by up to a half in midsummer after flowering. Do not cut into older wood as the stumps may not regrow.”