One of the best tools that you have as gardeners to help us determine 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.

In Oelwein you can determine when it's possible to plant marigold by using the USDA zone info.

Planting Calendar for Marigold

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

You can not plant marigold until after the last frost because they are not cold tolerant.

The earliest that you can plant marigold in Oelwein 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 marigold and expect a good harvest is probably August. If you wait any later than that and your marigold may not have a chance to really do well. You can get started a little bit earlier by starting your marigold indoors.

Last Frost Date

In Oelwein the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -20°F.

Since the USDA zone info for Oelwein is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Oelwein you get a frost after April 15 be ready to cover your marigold if you have a late frost.

USDA Zone Info for Oelwein

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Oelwein

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