There's just about enough time to cut back untidy and tired looking plants and perinnals, and its often a better option than having brown fading foilage. This works for some of the fast growing plants such as hardy geraniums, Nepeta (Cat Mint) Alchemilla (Lady's Mantle). The plant may already have started some new growth which can be seen spurting from centre of the plant. They may, or may not, floweragain depending on the weather but the plant will put on new foliage which will look fresh.

This photograph shows Alchemilla mollis which was cut back almost to the ground around second week of  July and this photo was taken at the end of July. The new growth has replaced the tired browning foilage, a little of which can be seen just in the top right of the photograph.