We had a very severe winter on central vancouver island - DEC TO MARCH. Temperatures were as low as 18 degrees below celcius on some nights. In some places around here snow was on the ground for at least two months. Some of the arctic outflow winds were severe as well. I trimmed two california lilacs last fall. This spring they are deader than door nails - Was it the trim or the weather?
Many ceanothus perished on Van. Isle and the lower mainland this winter, so likely the weather. They don't tolerate major pruning however; so, depending on your definition of 'trimming', that would otherwise be the culprit. Look no farther than the weather this season, though.
Many were lost up there without the pruning. However, if you whacked them way back last fall that was also a mistake. Flower buds are set the previous year, fall pruning takes the bloom for the new year away. Like brooms (Cytisus etc.) these do not come back at all well after cutting to/into old wood. To control size you need instead to prune each year right after bloom, staying out near the surface of the shrub. A large-growing kind so treated will still eventually get big. To avoid ending up with a bigger bush than you wanted at first choose another kind at the outset. Or plan on a comparatively short-term use of the plant. Like butterfly bush, abelia and escallonia these are fast-growing short-lived shrubs that like warm, sunny positions and may be damaged by cold to varying extent. They can be used intentionally for short-term purposes like quick filler near slower growing, longer lived shrubs.
I was hoping I could reply with a question on the same topic being a newbie and not posting before. I have a hedge in of California lilac in West Van that was frost damaged this past winter. It was about five years old and always bloomed beautifully. The lower parts of the hedge appear to be quite dead but if I scratch the bark it’s still green underneath. Part of the hedge still has green leaves on the top. I was wondering if anyone knows if I cut it back severely will it put out new shoots, or should I wait a couple more months and see if new growth will appear lower down, or should I just rip them out and start over.
May come back from low down. You might want to clear the dead-looking parts away in the mean time, just so you don't have to look at it. However, you may also want to replace it with another, more reliable selection so you don't have to risk it freezing off again later. Architectural effects like hedges are best accomplished using stalwart shrubs like yew, holly and box. There are yew hedges centuries old. There won't ever be any ceanothus hedges centuries old. Even where these are completely hardy.
Definitely to the observer and the experimenter with Ceonothus, as an easterner I was blown away by seeing a few huge specimen varieties near where we live, one in the Blenkinsop ALR area, and wondered as a newcomer what these wonderful huge treelike things were with the deep blue bloom presence. I tried one as a filler, and discovered that they have some awkward characteristics. I have just cut off two sideways sections of one, removing two "trunks", and the remainder is single-trunked and like a small new tree now, it may be worth keeping for a while if it blooms in the remaining portion. They do need spreading space.