What to do in the garden in October.

What a native planting asks for this month, split by how cold the winter gets where you are. Timing here is typical rather than predicted: every line is written against something you can see outside (ground frozen, soil workable, stems browned) rather than against a date.

In colder states and the middle of the country

Leave the leaves where you can. They are habitat, they are free mulch, and raking them away throws out much of next year's insect life.
Water anything planted this fall until the ground freezes. A dry root going into winter is the usual reason a fall planting fails.
Mulch new plantings after the first hard frost, not before, so you are insulating cold ground rather than trapping warmth and rot.

In milder states

When the leaves come down, leave them where you can. They are habitat, they are free mulch, and raking them away throws out much of next year's insect life.
Water anything planted this fall through every dry spell. In a mild winter the roots are still working, and a dry spell is the usual reason a fall planting struggles.

Which band is your state in

Colder states (warm end at zone 5 or below): Minnesota, Montana, North Dakota, South Dakota, Vermont, Wisconsin, Wyoming

The middle (most of the country): Arizona, Arkansas, California, Colorado, Connecticut, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Missouri, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, Tennessee, Texas, Utah, Virginia, Washington, West Virginia

Milder states (cold end at zone 7 or above): Alabama, Delaware, Florida, Louisiana, Mississippi, South Carolina, Washington, D.C.

Your state guide carries the species that are in flower there right now, and the list your state publishes.