Zone 4 Planting Calendar: What to Start and When

Zone 4 winters average yearly lows from minus 30 to minus 20 degrees Fahrenheit. That helps with perennials, while a planting schedule comes from frost and soil data.

Key points

Zone 4 describes winter cold, not frost dates.
Start long-season crops indoors using the countback method.
Direct sow hardy crops early and tender crops after warm soil.
Keep covers ready and log results each year.
Write down what happened each season, and let your own record override any generic chart.

What does zone 4 mean for planting?

Zone 4 covers areas whose average annual extreme minimum falls between minus 30 and minus 20 degrees Fahrenheit. It guides perennial and overwintering choices. It does not give the date frost ends, so it should not be used to schedule tomatoes or beans.

Instead, find frost probabilities from the station closest to your land, and choose a threshold and a risk level before you write any dates.

If you are unsure how early to sow a crop, begin with a small test planting a week or two ahead of your main sowing, and keep notes on emergence. A small loss is cheap, and the information helps in every later season.

What do you start indoors?

Warm-season crops that need a long run, such as tomatoes, peppers and eggplant, are usually started indoors so transplants are ready as frost risk fades. Some brassicas also do better from transplants. Use the countback method: take your planting-out date, subtract the weeks of indoor growth listed for the crop, and mark the sowing day.

Check your extension service for the weeks that suit your area, since packet guidance is general.

Soil type matters as well. Sandy ground warms sooner than heavy clay, and a raised bed warms sooner than flat ground, so the same crop can be ready for sowing on different days in different beds.

Count backward from the planting-out date.
Allow for hardening off.
Stagger sowings in case of a late spring.

What do you sow directly, and when?

Hardy crops go in as soon as the soil can be worked. These include peas, spinach, lettuce, radishes and many root crops. Use the count-forward method for half-hardy crops near your spring anchor, and wait for warm soil before sowing beans, squash and corn.

University of Wisconsin guidance recommends reading soil temperature on several mornings in a row, and a similar approach works well in colder climates where spring warms in fits and starts.

Cold frames, low tunnels and row cover are all useful on both ends of the season. They add a few degrees on cold nights, protect against wind and let you sow or harvest a little beyond the open-ground window.

How do you handle late spring cold?

Keep row cover or bed sheets close at hand until at least a week or two after your chosen frost date. Delay planting out when a cold spell is forecast, and keep transplants in a sheltered spot. Cold soil stalls tender crops even when frost does not occur.

For example, if your transplants are ready but soil is cold and nights are dropping, wait. A week of delay costs less than a stand that stalls.

Keep your calendar flexible. A zone 4 spring can arrive early one year and late the next, and a plan with room to shift will serve you better than a fixed list of dates.

What about midsummer and fall?

Count back from your first fall frost to place fall crops, using days to maturity and extra days for slower fall growth. Quick crops like lettuce, spinach and radishes can follow early crops in the same beds. Protect tender crops on frost nights to extend harvest.

Garlic and some cover crops are planted in fall in many cold regions. Ask your extension office for planting windows that fit your site.

Label your trays and rows with sowing dates, since a few weeks later the seedlings all look alike.

How do you tune the calendar each year?

Record the actual last and first frost, planting dates, emergence dates and harvest dates. Compare them with your plan. After a few seasons, you will see where the published frost table agrees with your site and where it does not.

Adjust each bed too. A sheltered south-facing bed and a low corner can be days apart, so note your results by bed.

What mistakes should you avoid?

Planting tender crops after one warm week is the common one. Starting seed too early indoors is another. A third is using a zone-based planting chart as if it listed dates for your farm.

Write down your frost anchors before you begin, and let them guide the work.

When to get local help: Your county extension office can supply frost probability tables and recommended transplant timing for your part of zone 4.

Sources and further reading

Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.

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