One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when it's the best time to plant sweet corn in Helena by checking out the USDA zone info.

Planting Calendar for Sweet corn

Frost tolerance for sweet corn:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since sweet corn do ok in moderate cold you can plant them just a tiny bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant sweet corn 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 sweet corn and expect a good harvest is probably August. If you wait any later than that and your sweet corn may not have a chance to grow to maturity. If you are starting your sweet corn indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on March 15 in Helena. In the coldest months of winter you can expect an average low temperature of 10°F.

Just be sure to remember that USDA zone info for Helena is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Helena there is a last frost after March 15 so make sure that you are prepared to cover your sweet corn if you have a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Helena

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