Late summer and early fall, such as September, is the best time to plant chrysanthemums which are hardy perennials that will grow back each and every year with the proper care. Peonies are also perennials, so after you plant them once in September, they'll come back year after year with the proper care.
Flowers to plant in September
English marigold (Calendula) has deep orange petals, which are perfect for a hot border or for cutting. It's easy to grow – from an autumn sowing it should flower from May. Sow direct into shallow drills or on the surface of moist peat-free compost, in pots.
Late summer or early fall is an excellent time to plant mums, one of the symbolic flowers of the season. Practically any time in September that strikes your fancy is a good bet, so long as it's at least six weeks before the year's first frost.
It's time for planting fall color, such as mums and asters, as well as sprucing up planter boxes. You also may be surprised to learn that it's the best time of year to plant perennials and shrubs (trees, too!) while plants still have an opportunity to establish their root systems before the ground freezes.
Plants like chrysanthemums, nasturtiums and asters are wonderful choices for seasonal planting arrangements. While perennials that will survive the winter are great choices, autumn is also a great time to explore new ideas will short-season annuals too.
Violas and Pansies
These hardy little flowers not only have gorgeous blooms but can survive almost anything winter has to dish out. Violas and pansies grow best in partial shade but need a minimum of four hours of sunlight a day.
October is the season to plant spring-blooming bulbs, wildflowers, and many standard gardening favorites. The flowers that don't blossom this winter can spend the cold season in the ground, strengthening their root systems in preparation for a springtime bloom.
Plant wallflowers, forget-me-not, Bellis, Primula, Viola (including winter pansies) and other spring bedding plants in prepared ground or pots.
Vegetables to plant in September: Beets, broccoli, bush beans, pole beans, carrots, cauliflower, collards, cucumbers, kale, kohlrabi, lettuce, onions (seed & sets), radishes, summer squash and turnips.
A: In Southern California, it's never too late to plant rosebushes. The popular “Iceberg” roses are super hardy and will rebloom without constant deadheading. They are also available in pink and burgundy flowered varieties. If you want to plant any perennials, it's a good idea to do it sooner rather than later.
Tip. Mid- to late-August is often an excellent time to plant fall flowers, as long as the weather isn't still so hot that the plants will suffer heat stress. But don't wait too late to plant, or you'll have a very short window to enjoy your flowers. Check the growing requirements for each plant.
Plant Flowers and Vegetables
If you live in a frost-free region, October is a great time to plant cool-weather flowers and vegetables in your garden. Crops such as kale, cabbage, collards, lettuce, carrots, mustard, onions, Brussels sprouts, cauliflower, beets, and garlic can all be planted in early to late October.
Plants in the Cole or Brassica family are perfect crops you can plant in August. Broccoli, cabbage, cauliflower, kohlrabi, and Brussels sprouts all do very well in the fall.
From early fall through most of November is one of the best times of year to plant spring-blooming bulbs, cool-season annuals and vegetables, as well as many trees, shrubs, and perennials.
Autumn is a great season for annuals, low-maintenance perennials and evergreen shrubs to shine. In fact, some of the most popular flowers, like colorful mums, roses, dahlias, purple pansies and yes, even bright yellow sunflowers, all bloom around September and October.
In areas with cold winters, such as USDA Hardiness zones 5 and 6, you'll generally want to wrap up fall planting by late October, and by mid-October in zones 3 and 4. But better late than never!
Generally speaking, spring-flowering bulbs should be planted in the fall (a few weeks before first frost), while summer-flowering bulbs should be planted in the spring (a few weeks after last frost).
Christmas Rose. This evergreen perennial blooms from winter to early spring depending on the selection and where you live (mostly early winter in warmer regions, and as late as February or March where it's very cold).
Winter pansies are cold weather all-stars. These cheery winter blooming flowers can freeze solid and emerge from that state ready to grow and flower. Other bedding plant flowers that grow in winter include nemesia, snapdragon, sweet alyssum and flowering stock.