Before planting it is a good idea to find your USDA Zone info to determine 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 Havre can be looked at to determine when it's the best time to plant lobelia.

Planting Calendar for Lobelia

Frost tolerance for lobelia:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Lobelia can survive in pretty solid cold which means that you can plant them earlier in the year than plants that are more sensitive to the cold.

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

The last month that you can plant lobelia and expect a good harvest is probably August. Any later than that and your lobelia may not have a chance to really do well. You can get started a little bit earlier by starting your lobelia indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Havre. You should expect an average low temperature of -30°F in the coldest months of winter.

Always keep in mind 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 Havre and it changes from year to year. Half of the time in Havre there is a last frost after May 15 so make sure that you are ready to protect your lobelia in the event of one of those late frosts.

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.