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

The USDA zone info for Great Falls can be read to estimate when it's possible to plant gladiolus.

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.

Since gladiolus are barely cold tolerant you can plant them slightly earlier in the year than more sensitive plants.

The earliest that you can plant gladiolus in Great Falls is April. However, you really should wait until May 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 few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Great Falls. It might get as low as -30°F during the coldest months of winter.

Always keep in mind that USDA zone info for Great Falls is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Great Falls last frost occurs after May 15 so make sure that you are ready to cover your gladiolus if you have a surprise late frost.

USDA Zone Info for Great Falls

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 Great Falls

You may be interested in your other planting guides for Great Falls.