When to Plant Begonias in USDA Zone 4b
July in the garden — Zone 4b
Each item below is timed to Zone 4b's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Sow begonias in trays indoors
Starting these indoors now means sturdy transplants ready the moment your soil warms up.
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Start harvesting begonias
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
August prep starts now
- First harvests: begonias
Wax begonias (Begonia × semperflorens) are the workhorse shade bedding plant of American horticulture, offering continuous bloom from transplant to hard frost. Bronze or green-leaved varieties perform well from deep shade to full sun (in northern zones) and tolerate summer humidity better than most cool- season flowers. A staple of mass plantings, containers, and window boxes.
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.
Begonias 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 Begonias planting schedule for that location.
Begonias Planting Calendar — Zone 4b
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 13 | Feb 13 – Feb 27 |
| Transplant Outdoors | May 8 | May 8 – May 22 |
| Bloom | July 17 | Jul 17 – Sep 25 |
· 8" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| 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
70–90 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
| Plant Spacing | 8 inches apart |
| Row Spacing | 10 inches between rows |
Succession Planting Begonias in Zone 4b
Sow every 8 weeks for continuous harvest throughout the season.
Growing Tips for Begonias in Zone 4b
Zone 4b has a short growing season (~155 days). Start Begonias indoors early and use season-extension techniques like row covers and cold frames.
Start seeds indoors 10–12 weeks before last frost — seed is dust-fine; surface-sow on moist mix under lights, do not cover. Bottom heat (70–75°F) speeds germination. Transplant after frost; begonias are not direct-sown in practice. Pinch seedlings once for branching. Keep soil evenly moist; avoid waterlogged conditions. Bronze-leaf types tolerate more sun; green- leaf types prefer shade to part-sun.
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
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Saving Begonias 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
Begonias in Other Zones
Begonias 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 Begonias in Zone 4b?
In Zone 4b, plan your Begonias planting around the average last frost date of May 1. Start seeds indoors around February 13. Transplant seedlings around May 8.
Can Begonias grow in Zone 4b?
Yes, Begonias can grow well in Zone 4b, hardy in USDA zones 2a through 11b. Zone 4b has a growing season of approximately 155 days, which is sufficient for Begonias (70-90 days to maturity).
When can I harvest Begonias in Zone 4b?
In Zone 4b, expect to harvest Begonias from July 17 – September 25. Begonias takes 70-90 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 Begonias?
Good companion plants for Begonias include Impatiens, Lobelia, Sweet Alyssum, Ferns. 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.