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

The earliest that you can plant four o' clock in Waterloo can be figured out by checking out the USDA zone info.

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 probably not a good idea to plant four o' clock until after the last frost because they require warm weather.

The earliest that you can plant four o' clock in Waterloo 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. You probably don't want to wait any later than that or else 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 little bit earlier.

Last Frost Date

In Waterloo the average date of last frost happens on April 15. You should expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Waterloo is an average the actual date of last frost changes from year to year. Half of the time in Waterloo last frost occurs after April 15 so just be sure to be ready to cover your four o' clock in the event of a late frost.

USDA Zone Info for Waterloo

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Waterloo

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