One of the first steps you take when you are getting a good idea 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.

You should be able to figure out when to plant hollyhocks by reviewing the USDA zone info for Idaho Falls.

Planting Calendar for Hollyhocks

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

Since hollyhocks do well in moderate cold you can plant them just a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant hollyhocks in Idaho Falls is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant hollyhocks and expect a good harvest is probably September. Any later than that and your hollyhocks may not have a chance to really do well. Starting your hollyhocks indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Idaho Falls. It might get as low as -20°F during the coldest months of winter.

Keep in mind that USDA zone info for Idaho Falls is an average and the actual date of last frost changes from year to year. Half of the time in Idaho Falls last frost occurs after April 15 so always be ready to protect your hollyhocks in the event of a late frost.

USDA Zone Info for Idaho Falls

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Idaho Falls

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