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

The USDA zone info for Longmont can be used to determine when it's a good idea to plant common hollyhock.

Planting Calendar for Common hollyhock

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

Since common hollyhock are moderately cold tolerant you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant common hollyhock in Longmont 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 common hollyhock and expect a good harvest is probably September. Any later than that and your common hollyhock may not have a chance to really do well. You can get started a little bit earlier by starting your common hollyhock indoors.

Last Frost Date

The average date of last frost is April 15 in Longmont. In the coldest months of winter you should expect an average low temperature of -15°F.

Keep in mind that USDA zone info for Longmont is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Longmont it frosts late in the year after April 15 be ready to cover your common hollyhock in the event of a late frost.

USDA Zone Info for Longmont

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

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

Plants to Grow in Longmont

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