Answer: In your area you can plant container grown trees and shrubs any time the ground is workable, meaning not too wet and not frozen. Evergreens however are usually better planted in the spring.
Most hardy perennials can be planted up to about 8 weeks before the ground freezes in the fall. You could still plant these now, but not too much longer.
Spring flowering bulbs are planted in the fall, once the soil has cooled to about 65 degrees. IF you plant them too soon they will not perform well.
After planting, water thoroughly to settle the soil and then mulch with an organic mulch. The mulch should be several inches thick in a flat layer over the root area; it should not touch the bark or stems of the plant. You could use shredded bark, pine fines, chopped leaves, or straw for example, depending on what is easily available locally.
Your local professional nursery staff and/or county extension should be able to help you identify plants that would do well in your yard and also meet your design goals. Enjoy your new plants!
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