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

By referring to the USDA zone info for Ontario you will be able to determine when it's a good idea to plant sweet williams.

Planting Calendar for Sweet Williams

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

Sweet Williams do well in some cold which tells us that you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant sweet williams in Ontario is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant sweet williams and expect a good harvest is probably October. If you wait any later than that and your sweet williams may not have a chance to really do well. You can get started a little bit earlier by starting your sweet williams indoors.

Last Frost Date

On average the last frost has passed is on January 31 in Ontario. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Ontario may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Ontario you get a frost after January 31 so make sure that you are ready to protect your sweet williams in the event of a surprise late frost.

USDA Zone Info for Ontario

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Ontario

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