Plant flowers that attract bees. First one that comes to mind is agastache. I planted some for the first time last year and was amazed at the number of honey bees attracted to it.

Have you visited the bee forum on GW?

The bees and butterflies love my lantana. Try planting cosmos, zinnias, sunflowers, and marigolds near your tomato plants. The bees love these flowers. The seeds are cheap and they are easy to grow.

It's not for lack of flowers. I've been raising bee attractant plants, but not even my clover had many bees last year. My confederate jasmine had a fair number of bumblebees but the regular honeybee population was way down.

I'm going to try a couple things this year. I'll put out some mason bee nesting sites and see if any are used. And promote the flowers again, of course.