Shrubs and trees can go into the ground later, but for best winter survival rates, you should have all plants in place by six weeks before soil typically freezes.
Fall and winter vegetables can be started by seed from late August to mid-September, then transplanted into the garden later. Seeds should be started indoors where temperatures are cooler, then the seedlings slowly transitioned outside once temperatures cool down in early October.
While you can plant a late planting to the first frost date, it's always best to allow as much growing time as possible. If you missed the spring planting, then calculate which vegetables you can grow now and still have a harvest before the first frost.
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.
Fall and Winter LEAFY GREENS
A beautiful sampling of some of the leafy greens you can grow in your fall and winter garden, including different varieties of kale, spinach, lettuce, chicory, and even wild chickweed! Spinach is a very fast-growing, cool weather vegetable.
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.
In general, aim to finish your fall planting about 6 weeks before your first expected frost date (8 weeks for evergreens). In Zones 3 and 4, you would count back from the latter half of September.
You can transplant perennials anytime until the ground freezes in the fall, or wait to transplant them in the spring. Fall is an excellent time to transplant herbaceous perennials because your plants will then have three seasons to establish a good root system before hot summer weather sets in next year.
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.
The most vigorous growth of plants will be in the summer when the sun is up and out the longest. During winter, the sun is neither as high in the sky, nor in the sky for as long as it is in the summer. For your plants, that means less light. For some plants, this may trigger dormancy.
There is still time to have fresh homegrown produce for fall. Most fall crops are started from seed in May, June and July. In August, if you haven't already started seeds for fall, it is best to buy established plant starts.
It's important to cut back foliage in the fall to protect flowering plants from disease and give them a clean start for regrowth as winter starts to turn into spring. However, there are some plants you can keep around through the winter since they benefit wildlife and still offer visual interest for your home.
You need to be planting seeds and seedlings for your fall and winter garden between 6 to 8 weeks before your average first frost date. Some even as early as 10 weeks.
Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation. Severe or hard freeze - 25° Fahrenheit and colder causes heavy damage to most plants.
Fall is a great time to plant perennial herbs, which come back year after year and thrive in either pots or planting beds. Plant herbs such as thyme, oregano, mint, and sage any time from summer to mid fall, and you'll be able to harvest now and up until a hard freeze.
For a cool-weather vegetable harvest, plant lettuce, collards, carrots, Brussel sprouts, spinach, broccoli, radish, and more. The general rule of thumb is to plant fall vegetables from seed 90 days before the first frost.
Fall is Good for Root Growth
Warm soil temperatures encourage root growth – more so than in the spring when the soil is still warming up. Plus, with the shorter days and cooler air temperatures, plants spend less energy on growing foliage and flowers and more on building a strong root system in preparation for winter.
You can sow seeds for winter vegetable crops, like salad greens, radishes, carrots, onions, Swiss chard, English peas and kale. Look for transplants of other cool-season vegetables, including Brussels sprouts, broccoli and cauliflower. Herb transplants also appear in garden centers during winter.
Fall tends to produce more good planting days than Spring.
Another significant advantage during the Fall is that common garden pests and disease problems are less of a problem. Whether you are planting grasses, spring-blooming bulbs, perennials, trees or shrubs, they all will do great when planted in the Fall!
After planting, if it's dry, water well several times after you plant. Fall bulbs don't readily root in dry soil. In places where there's a dry autumn and then a hard freeze, the bulbs can die because there's not enough moisture in the roots.