Bees are one of the most important pollinators for many vegetable crops, both for large scale production and in the home vegetable garden. For the gardener who does not want to deal with all that is involved in placing a beehive near the garden, the best way to attract bees so that they will pollinate vegetable crops is through the use of flowers.
Look around your yard and adjacent areas of your property to identify areas of native wildflowers. These areas are probably already attracting bees and should be protected in order to encourage the bees to return. Generally speaking, if you have enough room for a garden you may also have areas along a fence or at the back of your property that are a haven for bees much of the year.
Create an area around your garden in which you can plant flowers. Try not to disturb any flowering plants in this area. The goal is to enhance what is there rather than to replace it. The exception to this would be any natural plants that may infiltrate your garden and rob the vegetable plants of nutrition, light and water.
Select different kinds of flowering plants to place near your vegetable garden. Choose a variety of flower types and colors. The more variety there is, the more kinds of pollinators there are that will be attracted to them.
Choose plants that bloom at different times during the season. Plan to have something flowering all of the time, to encourage bees to stay in the area. If you provide nectar from flowers early in the season, hives will have a better chance of being solidly established in the area, resulting in plenty of bees for your garden.
Mix the flower species together when you plant them, so that all flowering areas near your garden have something of interest to the bees at all times. You can mix the flowers randomly or set them out in orderly rows, so long as you don't have large areas with no flowers at all during portions of the growing season.