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Zone 4B Vegetable Planting Calendar

When can you plant in Zone 4B? In Zone 4B, outdoor sowing opens with cool-season crops like Lettuce and Spinach in April, and warm-season crops like Tomato follow after the ~May 12 last frost. The season runs about 142 frost-free days, until ~October 1. The calendar below scores all 35 crops month by month.

Scored per crop from your zone's frost dates, each crop's days-to-maturity, and typical soil temperatures — honestly, including when not to plant.

A zone caveat: USDA zones reflect winter lows, not summer heat — this calendar is a zone-level guide. For timing tuned to your ZIP region, sun, and soil, get your free AI garden plan.

Last frost (50/50 date)

~May 12

First frost (50/50 date)

~October 1

A single frost date is a coin flip dressed up as a fact: these are the 50/50 dates, and about half of years see frost past them. Across 4,330 NOAA stations, frost odds typically stay near 1 in 3 for about a week past the date and don't drop below 1 in 10 until roughly 16 days past it — cautious growers wait those two-plus weeks; gamblers plant on the date and keep row cover handy. The free AI plan reads the real percentile dates for your ZIP region and lets you pick your risk.

Zone 4B Month by Month

The same verdicts as the grid, read as a to-do list. Temperatures are the zone-level model this calendar scores against — your bed's soil thermometer overrules them.

1. January soil ~30°F · highs ~34°F · 0 of 35 crops in a good window
   Nothing plants this month — order seed, build soil, and plan the beds.
2. February soil ~32°F · highs ~37°F · 0 of 35 crops in a good window
   Nothing plants this month — order seed, build soil, and plan the beds.
3. March soil ~39°F · highs ~46°F · 0 of 35 crops in a good window
   Start indoors: Onion, Tomato, Pepper, Eggplant, Sweet Potato, Rosemary, Thyme, Oregano, Chives, and Parsley. Nothing goes in the ground outdoors.
4. April soil ~48°F · highs ~58°F · 20 of 35 crops in a good window
   Opens: Lettuce, Spinach, Kale, Swiss Chard, Arugula, and Carrot and 14 more. Start indoors: Lettuce, Kale, Swiss Chard, Broccoli, Cabbage, Cauliflower, Basil, Zucchini, Cucumber, and Okra.
5. May soil ~57°F · highs ~70°F · 20 of 35 crops in a good window
   Nothing new opens or closes.
6. June soil ~63°F · highs ~79°F · 27 of 35 crops in a good window
   Opens: Tomato, Basil, Zucchini, Cucumber, Bean, and Corn and 1 more. Last good month for: Lettuce, Spinach, Arugula, Cilantro, Tomato, and Corn and 2 more. Risky: Pepper and Eggplant (soil still cool (~63°F)); Sweet Potato (short-season varieties only).
7. July soil ~66°F · highs ~82°F · 19 of 35 crops in a good window
   Last good month for: Cauliflower, Onion, Potato, Basil, Zucchini, and Cucumber and 1 more. Risky: Lettuce, Spinach, Arugula, and Cilantro and 1 more (heat bolting risk); Okra (short-season varieties only).
8. August soil ~63°F · highs ~79°F · 15 of 35 crops in a good window
   Opens: Spinach, Arugula, and Cilantro. Last good month for: Spinach, Kale, Swiss Chard, Arugula, Carrot, and Beet and 4 more. Risky: Lettuce (last sowing before the window closes); Cauliflower and Parsley (finishes just ahead of first frost).
9. September soil ~57°F · highs ~70°F · 6 of 35 crops in a good window
   Opens: Garlic. Last good month for: Radish. Risky: Spinach and Cilantro (finishes just ahead of first frost); Arugula (last sowing before the window closes).
10. October soil ~48°F · highs ~58°F · 5 of 35 crops in a good window
    Last good month for: Garlic, Rosemary, Thyme, Oregano, and Chives. Risky: Radish (finishes just ahead of first frost).
11. November soil ~39°F · highs ~46°F · 0 of 35 crops in a good window
    Risky: Garlic (shoulder of the garlic window).
12. December soil ~32°F · highs ~37°F · 0 of 35 crops in a good window
    Nothing plants this month — order seed, build soil, and plan the beds.

When to Start Seeds Indoors vs. Direct Sow in Zone 4B

In Zone 4B, start Onion, Rosemary, Eggplant and other transplants indoors 5–10 weeks before your ~May 12 last frost, then set them out once it passes. Arugula, Bean, Beet and the other direct-sow crops go straight into the bed. Exact indoor start dates for every crop are below.

Planting a fall garden? Count the indoor weeks back from your transplant date instead of the spring frost — the free AI plan's prep runway computes that per plant, including hardening-off days.

How Much Fits in a Zone 4B Season

• 18 of 35 crops have four or more good planting months in Zone 4B.
• Widest windows: Chives (7 months), Oregano (7 months), Rosemary (7 months).
• Tightest windows: Corn (1), Sunflower (1), Tomato (1), Basil (2), Bean (2), Cucumber (2) and 2 more — plant these on the first good month, not the last.
• Short-season varieties only: Okra and Sweet Potato — the standard varieties don't fit; pick the fastest days-to-maturity on the rack.
• Not recommended in Zone 4B: Cantaloupe, Pumpkin, and Watermelon — no month scores better than off-season.
• Good months per crop in Zone 4B: Chives 7 · Oregano 7 · Rosemary 7 · Thyme 7 · Radish 6 · Beet 5 · Broccoli 5 · Cabbage 5 · Carrot 5 · Kale 5 · Peas 5 · Swiss Chard 5 · Arugula 4 · Cauliflower 4 · Cilantro 4 · Onion 4 · Potato 4 · Spinach 4 · Lettuce 3 · Parsley 3 · Basil 2 · Bean 2 · Cucumber 2 · Garlic 2 · Zucchini 2 · Corn 1 · Sunflower 1 · Tomato 1 · Cantaloupe 0 · Eggplant 0 · Okra 0 · Pepper 0 · Pumpkin 0 · Sweet Potato 0 · Watermelon 0

Zone 4B Planting FAQ