The USDA Zone info is a great tool for gardeners to help us estimate 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.

By reviewing the USDA zone info for Duluth you will be able to estimate when it's the best time to plant iceberg lettuce.

Planting Calendar for Iceberg lettuce

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

You can plant iceberg lettuce slightly earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant iceberg lettuce in Duluth 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 iceberg lettuce and expect a good harvest is probably August. If you wait any later than that and your iceberg lettuce may not have a chance to fully mature. You can get started a few weeks earlier by starting your iceberg lettuce indoors.

Last Frost Date

The average date of last frost is May 15 in Duluth. You should expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Duluth is not always accurate the actual date of last frost will vary from year to year. Half of the time in Duluth you get surprised by a frost after May 15 so just be sure to be ready to protect your iceberg lettuce in the event of one of those late frosts.

USDA Zone Info for Duluth

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Duluth

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