Before planting it is a good idea to find your USDA Zone info to figure out your garden 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 Riverdale can be reffered to in order to determine when it's a good idea to plant calendula.

Planting Calendar for Calendula

Frost tolerance for calendula:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant calendula just a bit earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant calendula in Riverdale is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant calendula and expect a good harvest is probably September. If you wait any later than that and your calendula may not have a chance to grow to maturity. Starting your calendula indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Riverdale. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Riverdale is an average the actual date of last frost is different every year. Half of the time in Riverdale there is a last frost after April 15 so make sure that you are ready to protect your calendula if you have a late frost.

USDA Zone Info for Riverdale

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 Riverdale

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