When to Plant Bok Choy in USDA Zone 4a
Your June planting checklist for Zone 4a
Each item below is timed to Zone 4a's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Get bok choy seeds going inside
Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.
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Bring in the bok choy
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
Before July arrives, get these ready
- First harvests: bok choy
- Fall sowing: bok choy
Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.
In Zone 4a, the average last spring frost is around May 6 and the first fall frost is around September 28, giving you a growing season of approximately 145 days.
Bok Choy Planting Timeline — Zone 4a
Where Is USDA Zone 4a?
The map below highlights the states that contain Zone 4a. Click any state to see the Bok Choy planting schedule for that location.
Bok Choy Planting Calendar — Zone 4a
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 25 | Mar 25 – Apr 8 |
| Transplant Outdoors | May 6 | May 6 – May 20 |
| Direct Sow | April 29 | Apr 29 – May 20 |
| Harvest | June 17 | Jun 17 – Jul 22 |
| Fall Sowing | July 6 | Jul 6 – Jul 20 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Free Zone 4a Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 4a with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Partial Shade (3-6 hours)
💧 Water
High — keep soil consistently moist
Days to Maturity
40–60 days
Soil pH
6 – 7.5
Zone Temperature Range
-30°F to -25°F average annual minimum
Growing Season
145 days (Zone 4a average)
Planting Specifications
| Planting Depth | 1 inches |
| Plant Spacing | 15 inches apart |
| Row Spacing | 24 inches between rows |
Succession Planting Bok Choy in Zone 4a
Sow every 4.6 weeks for continuous harvest throughout the season.
Growing Tips for Bok Choy in Zone 4a
Zone 4a has a short growing season (~145 days). Start Bok Choy indoors early and use season-extension techniques like row covers and cold frames.
Direct sow in spring or fall for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.
Companion Planting
Good Companions
Avoid Planting Near
The Gardener's Encyclopedia to Companion Planting
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Saving Bok Choy Seeds
Recommended for Your Garden
Full-spectrum LED lights for starting seeds indoors when daylight is limited.
Warm soil for faster germination of heat-loving crops like tomatoes and peppers.
Protect plants from frost, wind, and pests while letting light and water through.
Related Plants
Bok Choy in Other Zones
Bok Choy by State
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Bok Choy in Zone 4a?
In Zone 4a, plan your Bok Choy planting around the average last frost date of May 6. Start seeds indoors around March 25. Direct sow outdoors around April 29. Transplant seedlings around May 6.
Can Bok Choy grow in Zone 4a?
Yes, Bok Choy can grow well in Zone 4a, hardy in USDA zones 2a through 11b. Zone 4a has a growing season of approximately 145 days, which is sufficient for Bok Choy (40-60 days to maturity).
When can I harvest Bok Choy in Zone 4a?
In Zone 4a, expect to harvest Bok Choy from June 17 – July 22. Bok Choy takes 40-60 days from planting to harvest.
What is the last frost date for Zone 4a?
The average last spring frost in Zone 4a is around May 6, and the first fall frost is around September 28. This gives a growing season of approximately 145 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Bok Choy?
Good companion plants for Bok Choy include Celery, Lettuce, Spinach. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 4a Garden Planner — Free
A 22-page printable planner tailored to Zone 4a. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.