One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Decorah should be looked at to figure out when to plant marigold.

Planting Calendar for Marigold

Frost tolerance for marigold:	Not tolerant of frost.
When to plant:	After the last frost.

Since marigold require warm weather it is important to wait until after the last frost before you can plant them.

The earliest that you can plant marigold in Decorah 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 marigold and expect a good harvest is probably August. You probably don't want to wait any later than that or else your marigold may not have a chance to fully mature. If you are starting your marigold indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Decorah the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Decorah and it can change quite a bit from year to year. Since half of the time in Decorah you get surprised by a frost after May 15 be ready to cover your marigold if you have a late frost.

USDA Zone Info for Decorah

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 Decorah

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