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.

You can determine when it's the best time to plant platycodon in Grinnell by checking out the USDA zone info.

Planting Calendar for Platycodon

Frost tolerance for platycodon:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since platycodon are one of those plants that can tolerate a tiny bit of cold weather you can plant them a bit earlier in the year than other frost tender plants.

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

The last month that you can plant platycodon and expect a good harvest is probably August. You probably don't want to wait any later than that or else your platycodon may not have a chance to fully mature. If you are starting your platycodon indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Always keep in mind that USDA zone info for Grinnell is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Grinnell there is a last frost after April 15 be ready to protect your platycodon if you have a surprise late frost.

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.