This is the month when the numbers of honey bees will reach their maximum and most of the other species are at peak as well. Therefore the demand for food is at its greatest. In the UK, there can be a lull in flower supply between the trees and herbaceous plants which is known by beekeepers as the June gap. For those who are interested in plants to address this issue then absolute best providers or nectar are all from the same family: borage, phacelia and echiums. Most are annuals or biennials but will self -seed reliably. The reason these are special for bees is that not only do they produce masses of nectar but they produce it all day long rather than just in the morning.
The phacelia is sometimes grown as a green manure but for the bees it must be allowed to flower (so probably not best in an area you were preparing for vegetables) and then you will be amazed how many bees you will get in a patch.
Plant any of these in blocks for maximum effect.
Other good bee plants in June are veronica spicata and salvia nemerosa; both great for bumblebees.