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.

The USDA zone info for Duluth can be looked at to determine when it's the best time to plant salpiglossis.

Planting Calendar for Salpiglossis

Frost tolerance for salpiglossis:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since salpiglossis require warm weather it is necessary to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant salpiglossis 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 salpiglossis and expect a good harvest is probably August. Any later than that and your salpiglossis may not have a chance to fully mature. Starting your salpiglossis indoors is a great way to get them started a couple of 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 the actual date of last frost is an average because it is based on the USDA zone info for Duluth and it is different every year. Half of the time in Duluth you get surprised by a frost after May 15 so be sure to be ready to protect your salpiglossis if you have a 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.