When to Plant Foxglove in USDA Zone 4b
What to do in June
Your garden in Zone 4b is working on a schedule, even when you're not. Here's where you should be this June.
Looking ahead to July
- Starting indoors: foxglove
- First harvests: foxglove
Foxglove (Digitalis purpurea) is a stately cottage garden classic, sending up dramatic 3–5 foot spires of tubular flowers — spotted purple, pink, white, or cream — in late spring and early summer. Technically biennial (flowering in its second year), foxglove perpetuates itself so freely from self-sown seed that established plantings appear to be permanent perennials. A key source plant for the heart medication digitalis, all parts are highly toxic if ingested. Bumblebees are the primary pollinators, crawling deep into each bell-shaped flower. Partial shade and cool, moist woodland-edge conditions suit foxglove best; it resents heat and drought.
In Zone 4b, the average last spring frost is around May 1 and the first fall frost is around October 3, giving you a growing season of approximately 155 days.
Foxglove Planting Timeline — Zone 4b
Where Is USDA Zone 4b?
The map below highlights the states that contain Zone 4b. Click any state to see the Foxglove planting schedule for that location.
Foxglove Planting Calendar — Zone 4b
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 20 | Feb 20 – Mar 6 |
| Transplant Outdoors | May 15 | May 15 – May 29 |
| Direct Sow | May 15 | May 15 – Jun 5 |
| Bloom | July 10 | Jul 10 – Aug 21 |
Plant 0.1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Direct Sow |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Free Zone 4b Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 4b with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Partial Shade (3-6 hours)
💧 Water
Moderate — regular watering
Days to Maturity
80–120 days
Soil pH
5.5 – 6.5
Zone Temperature Range
-25°F to -20°F average annual minimum
Growing Season
155 days (Zone 4b average)
Planting Specifications
| Planting Depth | 0.1 inches |
| Plant Spacing | 18 inches apart |
| Row Spacing | 24 inches between rows |
Succession Planting Foxglove in Zone 4b
Sow every 9.1 weeks for continuous harvest throughout the season.
Growing Tips for Foxglove in Zone 4b
Zone 4b has a short growing season (~155 days). Start Foxglove indoors early and use season-extension techniques like row covers and cold frames.
Sow seeds indoors 8–10 weeks before last frost or direct-sow outdoors in late spring/early summer for next-year bloom (biennial cycle). Surface-sow — seeds need light to germinate. Transplant after last frost into cool, moist, well-amended soil. Morning sun with afternoon shade is ideal; full shade reduces bloom but is tolerated. Keep consistently moist. First-year plants form a basal rosette only; second-year plants produce flower spikes. After bloom, cut the main spike before seed scatters to prevent excessive spreading, or leave some spikes to self-seed for naturalizing. Perennial species (D. grandiflora, D. x mertonensis) maintain clumps without requiring self-seeding. Wear gloves when handling — all plant parts toxic.
Companion Planting
Good Companions
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
Saving Foxglove 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
Foxglove in Other Zones
Foxglove 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 Foxglove in Zone 4b?
In Zone 4b, plan your Foxglove planting around the average last frost date of May 1. Start seeds indoors around February 20. Direct sow outdoors around May 15. Transplant seedlings around May 15.
Can Foxglove grow in Zone 4b?
Yes, Foxglove can grow well in Zone 4b, hardy in USDA zones 3a through 9a. Zone 4b has a growing season of approximately 155 days, which is sufficient for Foxglove (80-120 days to maturity).
When can I harvest Foxglove in Zone 4b?
In Zone 4b, expect to harvest Foxglove from July 10 – August 21. Foxglove takes 80-120 days from planting to harvest.
What is the last frost date for Zone 4b?
The average last spring frost in Zone 4b is around May 1, and the first fall frost is around October 3. This gives a growing season of approximately 155 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Foxglove?
Good companion plants for Foxglove include Hostas, Astilbe, Columbine, Bleeding Hearts. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 4b Garden Planner — Free
A 22-page printable planner tailored to Zone 4b. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.