Frost dates for Copper Harbor, MI
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
May 10
typical year
Safe to plant
June 2
frost is over in 9 of 10 years
First fall frost
October 21
typical year
Growing season
161 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Apr 12 – 26 | – |
| Spinach | – | Mar 29 – Apr 19 | Aug 26 – Sep 9 |
| Lettuce | – | Apr 12 – May 3 | Aug 26 – Sep 9 |
| Radishes | – | Apr 12 – May 24 | Sep 9 – 23 |
| Onions | – | Apr 12 – 26 | – |
| Potatoes | – | Apr 19 – May 3 | – |
| Carrots | – | Apr 19 – May 10 | Jul 29 – Aug 12 |
| Beets | – | Apr 12 – 26 | Aug 12 – 26 |
| Kale | Mar 1 – 15 | Apr 12 – 26 | Aug 12 – 26 |
| Broccoli | Mar 1 – 15 | Apr 26 – May 10 | Aug 12 – 26 |
| Cabbage | Feb 15 – Mar 1 | Apr 12 – 26 | Aug 12 – 26 |
| Garlic | – | – | Sep 9 – 30 |
| Warm-season crops | |||
| Tomatoes | Apr 7 – 21 | Jun 2 – 16 | – |
| Peppers | Mar 31 – Apr 14 | Jun 9 – 23 | – |
| Cucumbers | – | Jun 2 – 23 | – |
| Zucchini | – | Jun 2 – 30 | – |
| Pumpkins | – | Jun 2 – 23 | – |
| Green beans | – | Jun 2 – Aug 12 | – |
| Sweet corn | – | Jun 2 – 30 | – |
| Basil | Apr 28 – May 12 | Jun 9 – 16 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | June 2 | May 10 | April 26 |
| Fall frost before | October 3 | October 21 | November 5 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around April 27 (May 14 in a late year), and the first one in fall around November 3.
Where these dates come from
NOAA weather station COPPER HARBOR, MI US (USW00094899), 1991–2020 climate normals. It's the nearest station for 1 zip code, all within 13 miles:
49950
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.