One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Marengo you can estimate when you can plant heliotrope by referring to the USDA zone info.

Planting Calendar for Heliotrope

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

You really shouldn't plant heliotrope until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant heliotrope in Marengo 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 heliotrope and expect a good harvest is probably August. Any later than that and your heliotrope may not have a chance to grow to maturity. If you are starting your heliotrope indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Just be sure to remember that USDA zone info for Marengo is an average and the actual date of last frost will vary from year to year. Half of the time in Marengo last frost occurs after April 15 so make sure that you are ready to cover your heliotrope in the event of a surprise late frost.

USDA Zone Info for Marengo

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 Marengo

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