Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Helena you should be able to determine when it's the best time to plant myosotis.

Planting Calendar for Myosotis

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

Since myosotis are moderately cold tolerant you can plant them a little bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant myosotis 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 myosotis and expect a good harvest is probably August. You probably don't want to wait any later than that or else your myosotis may not have a chance to really do well. If you are starting your myosotis indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on May 15 in Helena. You should expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Helena is just an average the actual date of last frost is different every year. Half of the time in Helena there is a last frost after May 15 so be sure to be ready to cover your myosotis if you have a 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.