The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant zinnia in Ottawa can be determined by looking at the USDA zone info.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's probably a bad idea to plant zinnia until after the last frost when the weather gets warmer because they require warm weather.

The earliest that you can plant zinnia in Ottawa 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 zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to fully mature. Starting your zinnia indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

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

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Ottawa and it will vary from year to year. Half of the time in Ottawa it frosts late in the year after April 15 so be sure to be ready to cover your zinnia in the event of a late frost.

USDA Zone Info for Ottawa

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 Ottawa

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