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.

The first chance to plant thyme in Grinnell should be figured out by checking out the USDA zone info.

Planting Calendar for Thyme

Frost tolerance for thyme:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Thyme are very cold tolerant which tells us that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant thyme in Grinnell is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant thyme and expect a good harvest is probably September. You probably don't want to wait any later than that or else your thyme may not have a chance to really do well. Starting your thyme indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Grinnell. You can expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Grinnell may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Grinnell it frosts late in the year after April 15 be ready to cover your thyme if you have 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.