One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

The earliest that you can plant gladiolus in Helena should be determined by checking out the USDA zone info.

Planting Calendar for Gladiolus

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

Gladiolus are one of those plants that can tolerate a tiny bit of cold weather which means that you can get them planted just a bit earlier than other plants that might not handle the cold.

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

Last Frost Date

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

Since the USDA zone info for Helena is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Helena it frosts late in the year after March 15 be ready to protect your gladiolus 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.