When to Plant Sweet Pea in USDA Zone 5b
Sweet peas (Lathyrus odoratus) are beloved cool-season climbing annuals grown primarily for their intensely fragrant, ruffled blooms in shades of pink, purple, red, and white. They thrive in cool spring conditions, climbing trellises to 4–6 feet, and make outstanding cut flowers. Bloom ceases once summer heat arrives, making early sowing critical for a long cutting season.
In Zone 5b, the average last spring frost is around April 18 and the first fall frost is around October 13, giving you a growing season of approximately 178 days.
Sweet Pea Planting Timeline — Zone 5b
Where Is USDA Zone 5b?
The map below highlights the states that contain Zone 5b. Click any state to see the Sweet Pea planting schedule for that location.
Sweet Pea Planting Calendar — Zone 5b
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 7 | Mar 7 – Mar 21 |
| Transplant Outdoors | April 18 | Apr 18 – May 2 |
| Direct Sow | March 14 | Mar 14 – Apr 4 |
| Bloom | July 4 | Jul 4 – Sep 5 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | — |
| November | — |
| December | — |
Free Zone 5b Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 5b with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
Days to Maturity
65–85 days
Soil pH
7 – 7.5
Zone Temperature Range
-15°F to -10°F average annual minimum
Growing Season
178 days (Zone 5b average)
Planting Specifications
| Planting Depth | 0.5 inches |
| Plant Spacing | 6 inches apart |
| Row Spacing | 12 inches between rows |
Succession Planting Sweet Pea in Zone 5b
Sow every 7.4 weeks for continuous harvest throughout the season.
Growing Tips for Sweet Pea in Zone 5b
Soak seeds 24 hours before sowing to soften the hard seed coat; nick the seed coat with a file for the fastest germination. In cold zones (2–6), direct-sow as soon as soil can be worked, 4–6 weeks before last frost; seedlings tolerate light frost but not a hard freeze. In zones 7–9, fall-sow 8–10 weeks before first frost for earlier, stronger spring bloom. Provide a trellis or netting from the start. Feed with low-nitrogen, high-potassium fertilizer once buds form. Pick blooms regularly — even one mature seed pod stops flower production. All plant parts are mildly toxic if eaten.
Companion Planting
Good Companions
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Saving Sweet Pea Seeds
Recommended for Your Garden
Start seeds indoors with reusable cell trays and humidity domes.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Keep your garden organized with durable, weather-resistant plant labels.
Related Plants
Sweet Pea in Other Zones
Sweet Pea 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 Sweet Pea in Zone 5b?
In Zone 5b, plan your Sweet Pea planting around the average last frost date of April 18. Start seeds indoors around March 7. Direct sow outdoors around March 14. Transplant seedlings around April 18.
Can Sweet Pea grow in Zone 5b?
Yes, Sweet Pea can grow well in Zone 5b, hardy in USDA zones 2a through 9b. Zone 5b has a growing season of approximately 178 days, which is sufficient for Sweet Pea (65-85 days to maturity).
When can I harvest Sweet Pea in Zone 5b?
In Zone 5b, expect to harvest Sweet Pea from July 4 – September 5. Sweet Pea takes 65-85 days from planting to harvest.
What is the last frost date for Zone 5b?
The average last spring frost in Zone 5b is around April 18, and the first fall frost is around October 13. This gives a growing season of approximately 178 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Sweet Pea?
Good companion plants for Sweet Pea include Larkspur, Foxglove, Snapdragon, Dianthus. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 5b Garden Planner — Free
A 22-page printable planner tailored to Zone 5b. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.