The seasonal blackberry nectar flow is a prime example of the difference among microclimates in the maritime Pacific Northwest. In Seattle, the flow ended in the third week of June (June??). In North Bend, it’s just beginning. In both cases, the flow is early compared to recent years. What the norm is any more, who knows.
The next major flow will be knotweed, two months from now. With the dearth of pollen and nectar between these two major flows, your colonies will contract and be challenged. Recently you have rapidly been adding boxes, but now you may need to remove empty frames, or even boxes. Follow the guideline of having a 75% full box before adding an additional box.
You may need to feed: honey frames if you have them, 1:1 sugar syrup if you don’t.
Consider splitting large colonies to keep populations lower during the dearth and to create brood breaks for Varroa mite control.
In the city, cultivars may provide nectar and pollen sources not available in surrounding areas. Document this.
Patti Loesche, Bob Combs