Climate-based onion planting guide for Cody, Wyoming
When to Plant Onions in Cody: Timing and Maturity Guide
Onions are possible in Cody, though this is the kind of crop where planning details matter much more than they do for easier crops.
Typical Planting Window
Use the planting dates below for onions in Cody.
Gardeners usually start indoors around March 11 and plant outdoors from about May 6. Most varieties need about 95–110 days to reach maturity once they are in the garden.
Onions can still succeed in Cody, but the crop usually needs better-than-average planning around timing, variety speed, and site warmth.
Cody usually gets into onion planting season slightly later than many other Wyoming locations. That makes local site warmth more important than it would be where the seasonal margin is wider.
Best local strategy: Protect as much early momentum as possible and pair the crop with warm placement and realistic variety choice.
Can Onions Mature in Cody?
Growing degree days measure how much useful warmth typically accumulates during the season. For onions, this helps estimate whether local heat accumulation is usually enough for the crop to reach maturity on time.
From the usual planting window, Cody typically provides about 1355 growing degree days for onions. With a typical crop target of 1300, that leaves a heat margin of +55. That narrow heat margin means small delays or slower varieties can quickly reduce the odds of timely maturity.
GDD Checkpoints for Cody
When planting later than usual, this table shows how much growing degree day heat is still available from each point in the season. As planting gets pushed back, the remaining heat drops and the crop becomes less likely to mature on time.
| Checkpoint | Remaining GDD | Heat margin | Fit vs typical target |
|---|---|---|---|
| Apr 15 | 1365 | +65 | Usually fits |
| Jun 1 | 1327 | +27 | Tight fit |
| Jun 15 | 1248 | -52 | Usually short |
| Jul 1 | 1096 | -204 | Usually short |
Best Onion Varieties for Cody
In Cody, very early and early onion varieties are usually the best fit in a typical year. Slower choices can still work when gardeners want their specific qualities and do not give away margin through delay.
Varieties that often fit well here include:
- Walla Walla — large and popular, but still best when started early enough to build size
- Copra — a dependable storage onion with good all-around practicality
- Redwing — a strong red storage type where the season is reasonably supportive
- Patterson — a solid keeping onion that wants enough runway to size up well
| Variety class | Typical days to maturity | Typical GDD need | Local fit |
|---|---|---|---|
| Very early | 90–95 | 1100 | Good fit |
| Early | 95–105 | 1200 | Workable |
| Mid-season | 105–115 | 1300 | Tight |
| Late | 115–120 | 1400 | Tight |
Main risk: There is not much margin here, so late planting or longer-season onion varieties can easily carry harvest past frost.
How Frost Affects Onions in Cody
Cody usually has about 121 frost-free days, with a typical last spring frost around May 27 and a typical first fall frost around September 25.
Onions are generally lightly frost tolerant and temperatures below about 28°F ( -2 °C) can slow growth or damage plants.
Onions are usually tolerant enough of cool conditions that frost dates act more like planning markers than hard limits. In practice, timing and steady early growth matter more than avoiding every light frost.
The most common problem is running short on season. Late planting, slower varieties, and cooler exposed sites can turn a possible crop into a disappointing one.
In Cody, the seasonal margin for onions is tighter before the usual fall frost around September 25, so microclimate matters more than it does for easier crops. Local gardens do not all warm and cool at the same pace. For a better local margin, gardeners usually do best in south-facing walls, sheltered gardens, raised beds, and sunnier urban lots. Cooler spots like low spots, exposed sites, and shadier yards often make timing tighter. For onions, the best local sites often help the crop get moving earlier and make timing a little more forgiving.
Related crops
Related crops worth comparing for the same city:
For a broader local overview, see the Cody planting guide. You can also use the Growing Degree Day Planner to test planting dates and crop timing.