The cool fall weather causes plants that are new to your garden to transition more comfortably and get started on their root growth immediately when you put them in the ground. Fall planting also mean that there is less evaporation so the plants don't need as much water as they do on hot summer days. (Though, of course, newly planted items should still be watered well to help them to settle in no matter what time you plant them.)
If you're interested in wildflowers, fall is the time to plant those seeds, and always seek out 100% pure and fresh wildflower seeds that have no fillers or grasses included.
Trees and shrubs are excellent investments as they provide long-lived structure in a garden and are low maintenance once established.
There are also dwarf and slow-growing varieties available nowadays for gardens with space constraints. Shrubs can be planted in the fall to provide privacy and as windbreaks, as well as for their colorful blooms, berries and foliage. Look for those with multi seasonal appeal and good pest resistance.
For example, ‘Green Velvet' Korean boxwoods are hardy evergreens that provide compact structure, even in areas with severe winters. And ‘Hillside Black Beauty' Cimicifuga has dramatic dark foliage and spikes of white flowers in full or part shade. So those two shrubs are good possibilities for fall planting.