One of the first steps you take when you are estimating 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.

The best time to plant heliotrope in Havre should be determined by using the USDA zone info.

Planting Calendar for Heliotrope

Frost tolerance for heliotrope:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Heliotrope are not cold tolerant which tells us that it is important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant heliotrope in Havre is May. However, you really should wait until June 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. If you wait any later than that and your heliotrope may not have a chance to grow to maturity. Starting your heliotrope indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Havre the average date of last frost happens on May 15. In the coldest months of winter you can expect an average low temperature of -30°F.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Havre and it will vary from year to year. Half of the time in Havre you get a frost after May 15 so make sure that you are ready to protect your heliotrope if you have a surprise late frost.

USDA Zone Info for Havre

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Havre

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