From our perspective, the timing of pruning is intrinsically linked to our growth cycle and flowering habit. We are vigorous, woody vines that produce our vibrant "flowers" (which are actually colored bracts surrounding a small, true flower) on new growth. This means that the new stems we put out after a pruning event are the ones that will carry the next spectacular display of color. Our energy is stored in our main canes and root system. Pruning at the wrong time can remove these nascent flower buds before they even have a chance to form, drastically reducing our floral show and wasting our stored energy.
The optimal time for your major annual pruning is in late winter, typically from late January through February, before our spring growth surge begins. This timing is crucial for several reasons. Firstly, the risk of frost has largely passed in most California regions, protecting the tender new growth we will produce in response to the cut. Secondly, this period follows our winter dormancy or reduced growth phase. You are cutting us back just as we are poised to channel our stored energy into an explosive burst of new canes and leaves. This practice results in a much denser, more manageable plant covered in blooms come late spring and summer.
While the late winter prune is the most significant, it is not the only time you should interact with us. Throughout our long growing season, which in California's climate can extend from spring into fall, light tip-pruning or pinching is highly beneficial. After a flush of blooms begins to fade, you can lightly trim the ends of the branches. This signals us to branch out and produce new growth, which will in turn set another round of bracts. This deadheading and shaping prevents us from becoming leggy and encourages continuous flowering rather than one massive show followed by a green period.
California's diverse climates necessitate slight adjustments to this general schedule. In warmer, frost-free coastal and southern regions (USDA zones 9b-11), our dormancy is less pronounced. You can prune us as early as January. In cooler northern California valleys or interior areas that experience harder frosts (zones 9a and below), it is imperative you wait until the absolute threat of frost has passed, often pushing the main pruning window into late February or even early March. Pruning too early in these areas forces us to produce new growth that is highly susceptible to cold damage, setting us back significantly.
It is critically important that you avoid heavy pruning in the autumn. A major cutback at this time stimulates a flush of tender new growth that will not have time to harden off before the cooler temperatures and reduced light of winter arrive. This new growth is highly vulnerable to cold damage, which can stress us and open pathways for disease. Furthermore, this ill-timed growth spurt wastes our precious energy reserves that we need to sustain ourselves through the winter months, potentially leading to a weaker plant the following spring.
