Most perennials grown from seed can be planted in the garden after the average final frost date for your area. Once your garden is frost-free, you can safely plant your perennials. Some late-summer or fall-flowering perennials should be planted in the spring, according to the Virginia Cooperative Extension, but they will need enough time to become established before cold weather.
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Aileen Clarkson has been an award-winning editor and reporter for more than 20 years, earning three awards from the Society of Professional Journalists. She has worked for several newspapers, including "The Washington Post" and "The Charlotte Observer." Clarkson earned a Bachelor of Arts in journalism from the University of Florida.