If you think you've missed the boat in terms for seed sowing this year well you'd be wrong. There are a lot of quick growing vegetables and flowers that can sow now for harvests and flowers in late summer, autumn and winter.
July is also a very good month to start a lot of hardy biennial plants and some perennials for next year. The long lead in to the winter foliage die back give the plants a chance to establish their roots below ground and put on enough green growth to provide food for those roots to create robust plants come the spring next year.