This is a basic guide (the table below). It doesn't have as many
trees on it as I would like, though it has a few. I find that bee gardens are great, but trees are better in a way. Even if you have personal problems come up (a medical issue, major financial hurdle, farm projects, etc) and don't get around to planting a bee garden, the trees will still bloom--and are drought tolerant once established.
A good friend told me that there is a rough guide in
permaculture called the "80/20" rule. According to this, when you start you'll probably be getting around 80% of your food from annuals and 20% from perennials, and that the aim should be to work towards reversing that and eventually getting 80% of your food from perennials and 20% from annuals. I think with bee forage a similar goal should be held in mind. I find myself planting fewer sunflowers and less buckwheat and more bee trees. A bee tree is like a field of flowers in the sky that you don't have to
water (after establishment).
On a
permaculture homestead in the Pacific Northwest one is likely to have plenty of spring forage (fruit trees, hazelnuts, and
locust trees). This will
feed your bees from as soon as they are able to fly as things warm up (spring) into early summer. Summer forage is a little harder, especially as things dry up (literally). Summer blackberry is our biggest flow, but it's good to provide other forage for the sake of diversity. Fall is our absolutely biggest challenge--I can't stress that
enough. Sorrel trees are a good bet for this time, as are (possibly) silverberries, which bloom in November. My bees are still flying in November with how warm it's been. If anyone knows of some other drought tolerant fall perennial bee forage I'm all ears.
Note that this calendar, like many, lists sunflowers as blooming in September. This is highly misleading as sunflowers are more dynamic than that. Depending on care (watering), variety, and when you plant them, sunflowers can potentially bloom over a long period of time, possibly into October (and starting in mid summer). Buckwheat is similar in this regard. The issue with both is that it's difficult to plant enough to make a huge difference without tilling. Since I practice no till my space for this is limited, and that's part of why trees and perennials are so much more suitable for me.
Lastly, I just want to say that this is one good reason to please consider planting some standard fruit trees. They live a lot longer than dwarf and semi dwarf trees, which means that not only will they be feeding people and wildlife for a hundred or more years, but they will also provide food for pollinators. I have
apple trees on my property that were reputedly planted in 1926 and have probably been blooming and producing since the mid thirties. Every spring they still provide important forage for my bumblebees and
local honeybees, among others, and they fill my pantry, feed my extended family, and provide feed for livestock. I often say a prayer in thanks to the people who planted them.