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

You can determine when it's a good idea to plant sweet williams in Markham by using the USDA zone info.

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 are moderately cold tolerant which tells us that you can plant them a little bit earlier than more sensitive plants.

The earliest that you can plant sweet williams in Markham 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 sweet williams and expect a good harvest is probably September. If you wait any later than that and your sweet williams may not have a chance to grow to maturity. If you are starting your sweet williams indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Markham the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -15°F.

Just be sure to remember that USDA zone info for Markham is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Markham it frosts late in the year after April 15 so always be ready to cover your sweet williams in the event of a surprise late frost.

USDA Zone Info for Markham

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 Markham

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