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

The first chance to plant marigold in Ontario should be determined by looking at the USDA zone info.

Planting Calendar for Marigold

Frost tolerance for marigold:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Marigold require warm weather which means that it is necessary to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant marigold in Ontario 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 marigold and expect a good harvest is probably August. You probably don't want to wait any later than that or else your marigold may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your marigold indoors.

Last Frost Date

In Ontario the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Ontario is not always accurate the actual date of last frost is different every year. Half of the time in Ontario you get a frost after April 15 so make sure that you are ready to protect your marigold in the event of a surprise late frost.

USDA Zone Info for Ontario

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 Ontario

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