The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Ottawa you should be able 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 do well in moderate cold you can plant them a little earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant common hollyhock in Ottawa 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 fully mature. You can get started a couple of weeks earlier by starting your common hollyhock indoors.

Last Frost Date

The average date of last frost is April 15 in Ottawa. It might get as low as -10°F during the coldest months of winter.

Keep in mind that USDA zone info for Ottawa is just an average and the actual date of last frost will vary from year to year. Half of the time in Ottawa last frost occurs after April 15 so make sure that you are prepared to protect your common hollyhock if you have a surprise late frost.

USDA Zone Info for Ottawa

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Ottawa

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