One of the first steps you take when you are estimating your gardening schedule is find your 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 Union you can estimate when to plant marigold by looking at 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.

Since marigold are not cold tolerant you really should wait until after the last frost before you can plant them.

The earliest that you can plant marigold in Union 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 Union the average date of last frost happens on April 15. You can expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Union is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Union there is a last frost after April 15 so make sure that you are ready to cover your marigold in the event of one of those late frosts.

USDA Zone Info for Union

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Union

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