One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of estimating when it's the best time to plant four o' clock is to consult the USDA zone info for Zone 5b.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's not a good idea to plant four o' clock until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant four o' clock in Zone 5b 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. Any later than that and your four o' clock may not have a chance to fully mature. Starting your four o' clock indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Zone 5b. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Zone 5b may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Zone 5b last frost occurs after April 15 so make sure that you are ready to cover your four o' clock if you have a surprise late frost.

USDA Zone Info for Zone 5b

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 Zone 5b

You may be interested in your other planting guides for Zone 5b.