One of the major benefits of intermixing flowers into your garden (aside from pest prevention, nutrient balancing, & general aesthetics) is all of the pollinators that they'll bring your way. Bees and butterflies are so beneficial for your plants. These essential bugs are the reason why the flowers on your vegetable plant will eventually bear fruit. Without them, your plants rely on the wind or other insects to dislodge the pollen. If the pollen isn't disturbed at all, the flower will never turn into food. Bees are the best pollinators in the world for your plants, and if you successfully attract them to your garden, your yields will increase substantially.
The problem with attracting bees to your balcony garden is that you probably have limited space. The flowers on fruit and vegetable plants are typically small and not showy, and most of them aren't going to call out to traveling bees as a worthwhile place to land. That's why planting a few different varieties of flowers is so crucial. Flowers are usually much bigger, more fragrant, and more colorful. They'll successfully bring more bees your way, and your vegetable plants will benefit before they fly off again.
If you don't have a lot of space to dedicate to your planting yet, you need to get the most bang for your buck in terms of the flower varieties you choose. Here's are some of the best flowers for attracting pollinators to your garden.