Before planting it is a good idea to find your USDA Zone info to estimate 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.

You will be able to estimate when it's the best time to plant helianthemum by checking out the USDA zone info for Vincennes.

Planting Calendar for Helianthemum

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

Helianthemum do well in a little bit of cold which tells us that you can plant them just a bit earlier in the year than more sensitive plants.

The earliest that you can plant helianthemum in Vincennes 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 helianthemum and expect a good harvest is probably September. You probably don't want to wait any later than that or else your helianthemum may not have a chance to really do well. Starting your helianthemum indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Vincennes is an average the actual date of last frost is different every year. Since half of the time in Vincennes last frost occurs after April 15 be ready to cover your helianthemum if you have a surprise late frost.

USDA Zone Info for Vincennes

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 Vincennes

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