Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of getting a good idea when it's possible to plant four o' clock is to use the USDA zone info for Markham.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since four o' clock are not cold tolerant it's necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant four o' clock 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 four o' clock and expect a good harvest is probably August. If you wait any later than that and your four o' clock may not have a chance to grow to maturity. Starting your four o' clock indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Markham. In the coldest months of winter you should expect an average low temperature of -15°F.

Since the USDA zone info for Markham is not always accurate the actual date of last frost is different every year. Since half of the time in Markham it frosts late in the year after April 15 be ready to cover your four o' clock in the event of one of those late frosts.

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.