What to Plant in Fall in Northern Illinois
There is a moment every year, usually right around Labor Day, when folks decide the garden season is over. The tomatoes look tired, the zucchini has quit, and the whole thing gets written off until spring.
But gardening season doesn’t have to end with the pool season!
Fall is one of the best planting seasons we get all year, and for a lot of plants it beats spring outright. The soil is still warm from summer, the air has cooled off, and the fall rain does a good share of your watering for you.
The catch; Timing. What to plant in fall depends on which part of fall you mean, because late August, October, and November each want something different. Here is how we break it down, month by month, for gardeners in South Barrington, Schaumburg, Arlington Heights, Algonquin, and all around the ‘burbs.
Why Fall Planting Works So Well Here
Think about what a new plant actually wants. Warm soil to push roots into, cool air so the leaves are not stressed, and steady moisture. Spring gives you cold soil and warm air, which is backwards.
Fall gives you the reverse, and the reverse is better. Our Zone 5b yards typically see first frost around mid-October, but that frost date is not a wall. It stops top growth, not root growth, and roots keep working underground for weeks afterward, right up until the soil itself goes cold.
That is the whole secret of fall planting. You are buying your plants six extra weeks of root development that a spring planting never gets, as long as each thing goes in during the right stretch of the season.
Fall Planting at a Glance
Here is the whole season on one page. The details for each stretch follow below.
Late August
Cool-season vegetables from seed and transplants, and the start of the lawn’s best seeding window.
September
Trees, shrubs, and perennials, plus grass seed through mid-month and mums and pansies for color.
October
Spring bulbs and garlic once the soil cools, and the last of the trees and shrubs.
November
The final tulips and garlic before the ground freezes, and deep watering for everything new.
Late August: Cool-Season Vegetables
Late August is when the fall vegetable garden really gets planted. It feels early, with summer still hanging around, but the days are already shortening, and a crop sown now has just enough warm weather left to size up before frost.
Fast growers you can start from seed include lettuce, spinach, arugula, radishes, and mustard greens. From transplants, you can get in kale, Swiss chard, and broccoli if you find good-sized starts.
Plenty of these actually prefer the cooling weather, and some taste better after a light frost, because the plant converts starch to sugar to protect itself. Frost-kissed spinach is a genuinely different vegetable.
Count backward from a mid-October first frost, add about two weeks of cushion for the shorter days, and be honest about whether there is time. If you are running into September, lean toward the quick stuff. Radishes in 25 days will not let you down.
Mid-August to Mid-September: The Lawn’s Best Window
The stretch from mid-August to mid-September is the single best time of year to fix a Northern Illinois lawn. Cool nights, warm soil, and less weed pressure mean grass seed germinates fast and the seedlings actually survive.
Here is the order of operations that works.
- Mow shorter than usual for one cut so the seed can reach soil.
- Rake or dethatch the bare and thin patches until you can see dirt, because seed sitting on thatch will not take.
- Overseed the thin areas, using a bit more seed than feels necessary on the worst spots.
- Feed the lawn, since fall feeding builds roots rather than pushing soft top growth.
- Water lightly and often for the first two or three weeks, then taper back to deep, less frequent soaks.
Do that before mid-September and the difference next May is not subtle. A fall-seeded lawn comes out of winter thicker, and thick turf crowds out crabgrass on its own without you doing much of anything.
September: Trees, Shrubs, and Perennials
This one surprises people. Fall, not spring, is the ideal window for planting trees, shrubs, and perennials in our clay soil, and September is the heart of it.
A tree planted now spends September and October building roots with no leaves to support, then wakes up next spring already established. Perennials want the same head start, so aim to have them in by early October, and our guide to caring for perennials covers what comes after.
Water is the whole game. A newly planted tree wants a deep, slow soak once a week until the ground freezes. Mulch two to three inches over the root zone, but keep it pulled back from the trunk, since mulch piled against bark invites rot and voles. Doughnut, not volcano.
Pro Tip: Keep watering new trees and shrubs until the ground actually freezes, not until the leaves drop. Almost every fall-planted tree we hear about struggling next spring got cut off in early November because it looked dormant. Those roots are still drinking.
September and October: Mums, Asters, and Instant Color
Not everything you plant in fall is about next year. Sometimes you want the porch to look great this weekend, and that is a perfectly good reason to plant.
Mums, asters, ornamental kale and cabbage, and pansies all deliver color right now, and they carry a porch from September well into October. Pansies are the sleeper pick here, because they shrug off frost and often come back for a second show in early spring after the snow melts.
If you want your mums to last more than a couple of weeks, the watering and placement details matter a lot. We walk through all of it in our guide to caring for fall mums, including whether they will come back next year.
October: Spring Bulbs
Tulips, daffodils, crocus, alliums, and hyacinths all need a long cold period to bloom, which means they go in during fall for a show next April. Skip fall planting and there is no spring color, full stop.
Bulbs can go in any time from late September until the ground freezes, but October is the sweet spot here. The soil has cooled enough that bulbs settle in and root instead of sprouting early, and there are still weeks of workable ground ahead.
Here is a simple rule that covers almost every bulb you will buy.
- Plant depth: about three times the height of the bulb
- Pointy end up, flat root plate down
- Plant in clusters, not single-file rows, because five bulbs together read as a bouquet and one alone reads as an accident
- Skip the low spots where meltwater sits, since soggy bulbs rot
- Daffodils and alliums if deer and rabbits are a problem, because they leave those alone
Pro Tip: Plant your bulbs in layers in the same hole, like a lasagna. Big late bloomers such as tulips go deepest, mid-size daffodils in the middle, and small early crocus near the top. They come up in sequence out of one spot, and you get six weeks of color from a single afternoon of digging.
October: Garlic and Shallots
If you plant one edible thing this fall, make it garlic. It is nearly foolproof, it takes almost no space, and it is one of the few crops that genuinely must go in during fall.
Timing matters more than people expect. Planted too early, garlic pushes green growth that winter burns back, so aim for mid-October here, a few weeks before the ground freezes.
Break a head into individual cloves, leave the papery skin on, and plant each one pointy end up, about two inches deep and six inches apart. Then mulch a few inches of straw or shredded leaves over the top. That is the whole job.
The cloves send down roots this fall, sit tight through winter, push green shoots in April, and give you fat heads next July. Shallots follow the same playbook, and both taste dramatically better than what you get at the store.
November: Last Call Before the Ground Freezes
November is less about planting and more about finishing strong. Around here the ground usually does not freeze solid until late November or early December, which leaves a little time for stragglers.
Tulips and daffodils still left in the bag can go in as long as you can dig a hole, because an unplanted bulb does you no good in the garage. Garlic that missed October can still go in early in the month.
Keep watering anything new, trees and shrubs especially, until the ground actually freezes. Once it has, put winter mulch over perennials and bulb beds. Mulching after the freeze, not before, is what keeps the ground from heaving young plants out of our clay.
Fall Planting Questions, Answered
When is it too late to plant grass seed? Mid-September is the practical cutoff here. Later seed still sprouts, but the seedlings have less time to root before frost, so water carefully and expect to touch up thin spots in spring.
Will fall-planted perennials survive the winter? Generally yes, as long as they go in by early October and get watered until the ground freezes. Mulch after the ground firms up, which insulates against the freeze-and-thaw cycles that heave young plants out of our clay.
Should I fertilize what I plant in fall? Skip anything high in nitrogen, which pushes tender new growth that frost will just burn off. A starter fertilizer at planting time or a fall-formula lawn feed is a better fit.
What can I plant in fall if I only have containers? Bulbs do beautifully in pots for a spring display, and pansies, ornamental kale, and mums give you color right now. Just remember that a pot freezes far harder than the ground, so containers you want to overwinter should be tucked against the house or into an unheated garage.
What if we get an early frost? A light frost does not undo fall planting. Bulbs, garlic, trees, shrubs, and grass seed are all fine. Only the tender annual color on your porch needs covering or moving on a cold night.
Your Fall Planting Plan
The gardeners who get the best springs around here are the ones who are still working in September and October. It is quieter, cooler, and honestly a lot more pleasant than digging in July heat.
Figure out what to plant in the fall based on what you want next year, not just what looks good today. Spinach for the fall table. Garlic for the kitchen. Bulbs for April. A tree that will shade the patio in ten years. If you like to see the whole year laid out, our Chicago planting calendar picks up where this guide leaves off.
Stop by and tell us what you are hoping for. Whether you are in Barrington, South Barrington, Schaumburg, Hoffman Estates, Palatine, or Algonquin, our crew gardens in the same clay you do, and we are always happy to talk through timing before you buy. Come see us, then stay for the Fall Festival while the family is with you.
Questions? Talk to Goebbert’s
We would rather answer a question now than fix a problem later.
