Sunset Zones: 5 vs 4
I recall reading some time ago a comment on this forum to the effect that there isn't much to distinguish between Sunset zones 4 & 5. As a gardener who is clearly in Zone 4 and who is often a bit jealous of those in Zone 5, I beg to differ. I appreciate the distinction that Sunset makes between the two zones but would go even further and wish that they would nuance their maps a bit more to include some significant pockets of what appear to be Zone 5 climates in the PNW that they include in Zone 4.
One of our favourite activities in winter, especially in February is to visit gardens that clearly are in Zone 5 (e.g. Victoria or Seattle). It is always interesting not only to see how advanced Spring growth is by several weeks in such areas, but also the range of perennials and shrubs that appear to thrive that we usually can't grow in Zone 4 without winter protection (e.g., hebes, lithodora, sometimes even osteospermum etc).
Not only do my observations seem to validate Sunset's distinguishing between the two zones, I think that their editors err by not extending Zone 5 on their map to include sheltered areas such as the slopes south of Bellingham (above Fairview), the coastal area strethcing north and south around LaConner and, in BC, significant sheltered areas of the Gulf Islands and the south east side of Vancouver Island. From my observations, all of those areas seem to have significantly shorter winters than Zone 4 and are able to support Zone 5 type vegetation.
Do my observations seem off the mark to more experienced gardeners/observers?