One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Helena you will be able to estimate when you can 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 do well in cold which means that you can get them planted much earlier than plants that are more sensitive to the cold.

The earliest that you can plant lobelia in Helena 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. If you wait any later than that and your lobelia may not have a chance to grow to maturity. Starting your lobelia indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is May 15 in Helena. It might get as low as -25°F during the coldest months of winter.

Keep in mind that USDA zone info for Helena is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Helena last frost occurs after May 15 be ready to cover your lobelia if you have a surprise late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Helena

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