If you have ever grown mint, you know that it will take over whatever space it is occupying, so best to plant it alone in a pot. Pick a couple of decorative pots, plant some mint and place in your outdoor space. Not only will mint help repel the flies, you have the perfect garnish on hand for those summer night mojitos!
Lavender is a perennial plant that not only smells amazing and is beautiful to look at, it can also help repel those pesky flies! Again, I would recommend planting in a pot (if planting for the purpose of a fly repellent) and placing near your outdoor seating and entertaining space. Planting in a pot gives you the flexibility of moving the pot to different locations as well as moving the lavender into a protected space if you experience cold harsh winters.
Basil is another natural way to help repel those unwanted flies during the warmer months. The oil that puts off the sent form the basil plant is what the flies do not like, and this can be even more effective when the basil plant is moved around to different spots within your outdoor space; another reason a pot is a great idea!
So keep the flies away with mint, lavender and basil, while at the same time having all you need to make your favorite summer cocktails. Sounds like a win-win to me!