When to Plant Onions in Cody

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.

When Is It Too Late to Plant?

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.

How Different Onion Varieties Affect Results

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

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 Planting Dates for 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.