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

A way of making a decision about when it's a good idea to plant zucchini is to use the USDA zone info for Grinnell.

Planting Calendar for Zucchini

Frost tolerance for zucchini:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You can not plant zucchini until after the last frost because they do not do well in cold weather.

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

Last Frost Date

The average date of last frost is April 15 in Grinnell. In the coldest months of winter you should expect an average low temperature of -20°F.

Remember that USDA zone info for Grinnell is an average and the actual date of last frost changes from year to year. Half of the time in Grinnell there is a last frost after April 15 so make sure that you are prepared to protect your zucchini in the event of one of those late frosts.

USDA Zone Info for Grinnell

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 Grinnell

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