One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By checking out the USDA zone info for Markham you will be able to estimate when you can plant polygonums.

Planting Calendar for Polygonums

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

Polygonums are not cold tolerant which tells us that it's necessary to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant polygonums in Markham 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 polygonums and expect a good harvest is probably August. If you wait any later than that and your polygonums may not have a chance to fully mature. If you are starting your polygonums indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Markham and it will vary from year to year. Half of the time in Markham last frost occurs after April 15 so be sure to be ready to protect your polygonums if you have a 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.