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.
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.
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.
Mid-August to mid-October is an ideal time of year to plant new trees, though, that time frame can be stretched into November and December. To be 100% sure, measure soil temperature early in the morning for a few, consecutive days. If your soil is consistently 50° F or higher, you're good to plant.
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.
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.
For this Blooming Period, we're highlighting some late summer/fall favorites: callas; China asters; lisianthus; perennial sunflowers; and zinnias.
Fall is a great time to plant another crop of spring greens such as spinach, leaf lettuce, arugula, mustard greens, and mâche because they require cooler soil for seed germination and they mature quickly.
It's never too late. It just matters what you put into that garden. It's too late to grow tomatoes in your Chicago garden in September because you'll be getting cold weather soon, but you could still grow carrots, radishes, and lettuce plants.
Asters (Aster Spp.)
One very popular variety is Aster 'Celeste', which forms a clump covered with dense purple daisy-like flowers in late summer and early fall.
Plant wallflowers, forget-me-not, Bellis, Primula, Viola (including winter pansies) and other spring bedding plants in prepared ground or pots.
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.
Vegetables that can be planted in August include leafy greens such as lettuce, spinach, collards, kale and mustard. Radishes, turnips, beets and carrots can all be started from seeds in August.
Spirea has summer bloom types that bloom from July to September. It produces clusters of raspberry-rose flowers. Many varieties, such as 'Goldmound,' also offer attractive golden or lime-green foliage. These attractive shrubs are fast-growing and should be grown in full sun for the best flowering results.
Look for deals on spring-blooming bulbs, perennials, trees, and shrubs, which can all be planted in the fall, up until your area gets hit with a hard frost. And don't forget your lawn; cool-season turfgrass can be seeded this time of year, too.
Similarly to pansies, chrysanthemums or mums are best planted in October from an established plant rather than from seed. Keep in mind that these beautiful blooms can't typically survive winter weather conditions, but you can keep your mum plants living longer if you bring them indoors.
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!
1) Plant before frost. Check your local area's frost estimations and plant perennials at least 6 weeks before the first freeze. 2) Don't fertilize -- fall-planted perennials will be going into winter dormancy in their next stage of life and new growth (encouraged by feeding) will be killed when the first frost comes.