October is a great time to plant some cool season vegetables such as broccoli, lettuces, carrots, beets, tomatoes, radishes, and brussel sprouts. Mend the soil with some mushroom compost (or some of your own if you have it!), and dig holes twice the size of the pot so the soil is loosened and roots have room to expand.
Update your annual bed with things such as Snapdragons, Petunias, Alyssum, or Dusty Miller for a fresh winter look!
Keep in mind plants that bloom in the fall/ winter season that can give you some color/ foliage while your tropicals or perennials may have died back. Things like Camellias, Muhly Grass, and Cassias all give you cool season color.