The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Superior you can estimate when it's the best time to plant bunching onions by looking at the USDA zone info.

Planting Calendar for Bunching Onions

Frost tolerance for bunching onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since bunching onions are one of those plants that can tolerate a tiny bit of cold weather you can plant them slightly earlier in the year than other plants that might not handle the cold.

The earliest that you can plant bunching onions in Superior is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant bunching onions and expect a good harvest is probably August. If you wait any later than that and your bunching onions may not have a chance to grow to maturity. If you are starting your bunching onions indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Superior. You should expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Superior is an average the actual date of last frost is different every year. Since half of the time in Superior it frosts late in the year after May 15 be ready to cover your bunching onions in the event of one of those late frosts.

USDA Zone Info for Superior

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Superior

You may be interested in your other planting guides for Superior.