Prune annuals and roses. Although this is not the time of year for a hard (severe) pruning, many plants enjoy a bit of a haircut during the long, hot summer. Cascading annuals such as petunias often get leggy and stop blooming, so cut them back by half to promote bushier growth and increase flower production. Roses that are known to be repeat bloomers will also appreciate a light pruning to encourage a fall bloom cycle. Remember to fertilize your roses after pruning and water in thoroughly.