Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to figure out when it's the best time to plant marigold by referring to the USDA zone info for Rock Falls.

Planting Calendar for Marigold

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

Since marigold are not cold tolerant it is important to wait until after the last frost before you can plant them.

The earliest that you can plant marigold in Rock Falls 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. You probably don't want to wait any later than that or else your marigold may not have a chance to grow to maturity. If you are starting your marigold indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Rock Falls the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Rock Falls and it will vary from year to year. Since half of the time in Rock Falls you get surprised by a frost after April 15 be ready to protect your marigold if you have a late frost.

USDA Zone Info for Rock Falls

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Rock Falls

You may be interested in your other planting guides for Rock Falls.