One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can determine when it's a good idea to plant four-o-clock flower in Duluth by using the USDA zone info.

Planting Calendar for Four-o-clock flower

Frost tolerance for four-o-clock flower:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since four-o-clock flower do not do well in cold weather you really should wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant four-o-clock flower in Duluth is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant four-o-clock flower and expect a good harvest is probably August. If you wait any later than that and your four-o-clock flower may not have a chance to grow to maturity. Starting your four-o-clock flower indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Duluth the average date of last frost happens on May 15. It might get as low as -30°F during the coldest months of winter.

Keep in mind that USDA zone info for Duluth is not always accurate and the actual date of last frost changes from year to year. Since half of the time in Duluth last frost occurs after May 15 be ready to cover your four-o-clock flower if you have a surprise late frost.

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.