When to plant zinnias
Short answer
Plant zinnias about 1 week after your last spring frost. In a mid climate (zone 5) that's around Apr 22, starting seeds indoors about Mar 11. Enter your ZIP for your exact dates.
| Climate zone | Start indoors | Plant outside | Harvest |
|---|---|---|---|
| Zone 1 | Dec 11 | Jan 22 | Mar 28 |
| Zone 2 | Jan 11 | Feb 22 | Apr 28 |
| Zone 3 | Feb 3 | Mar 17 | May 21 |
| Zone 4 | Feb 23 | Apr 6 | Jun 10 |
| Zone 5 | Mar 11 | Apr 22 | Jun 26 |
| Zone 6 | Mar 26 | May 7 | Jul 11 |
| Zone 7 | Apr 10 | May 22 | Jul 26 |
| Zone 8 | Apr 27 | Jun 8 | Aug 12 |
Higher climate-zone numbers are colder, so planting shifts later. Zinnias is a tender crop. Enter your ZIP in the calculator for your exact zone and dates.
What sets the timing for zinnias
When to plant zinnias comes down to one date: your last spring frost. Zinnias is a tender crop, so it goes in about 1 week after your last spring frost. In a mid climate (zone 5) that's around Apr 22.
Give it a head start: sow seeds indoors about 5 weeks before your last spring frost (around Mar 11 in zone 5), then move seedlings out once conditions are right. From there it's roughly 65 days to first bloom.
Because that anchor date moves with climate, plant-out for zinnias ranges from about Mar 17 in warm zone 3 to May 22 in cold zone 7. Enter your ZIP in the calculator for the exact dates in your zone.
What sets the timing
| Factor | Effect on timing |
|---|---|
| Frost anchor | Timing counts from your last spring frost |
| Hardiness | Zinnias is tender — it waits until the soil warms after frost |
| Indoor start | Start seeds 5 weeks before your last spring frost |
| Days to harvest | About 65 days from planting to first bloom |
| Climate zone | Higher (colder) zones push plant-out later; warmer zones let you start sooner |
| Soil & weather | Needs warm soil — cold, wet ground stunts or rots it |
How zinnias compares
Plant-out date in a mid climate (zone 5), against an early hardy crop and a late tender one.
| Crop | Plant outside (zone 5) |
|---|---|
| Peas (hardy · plants early) | Mar 11 |
| Zinnias | Apr 22 |
| Tomatoes (tender · plants late) | Apr 29 |
Tips for growing zinnias
- Don't rush zinnias outside — cold soil stalls it. Wait until after your last spring frost and, ideally, until nights stay mild.
- Give zinnias a 5 weeks indoor head start under a bright light before transplanting.
- Count roughly 65 days from planting to first bloom, and stagger sowings a few weeks apart for a longer picking window.
- Enter your ZIP in the calculator for zinnias dates tuned to your exact climate zone.
Your exact dates
Open the planting calendarOther crops
Frequently asked questions
When should I plant zinnias?
Plant zinnias about 1 week after your last spring frost. That's around Apr 6 in zone 4 and May 7 in zone 6.
When do I start zinnias seeds indoors?
Start zinnias seeds indoors about 5 weeks before your last frost, then transplant after the frost passes. That's roughly Mar 26 in zone 6.
How long until zinnias blooms?
About 65 days from planting until first bloom. In zone 6, zinnias planted around May 7 is typically blooming near Jul 11.