Before planting it is a good idea to find your USDA Zone info to estimate 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.

By reviewing the USDA zone info for Zone 4b you should be able to estimate when it's the best time to plant platycodon.

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.

Platycodon can survive in a tiny bit of cold which means that you can plant them slightly earlier in the year than other plants that might not handle the cold.

The earliest that you can plant platycodon in Zone 4b 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 platycodon and expect a good harvest is probably August. Any later than that and your platycodon may not have a chance to fully mature. You can get started a little bit earlier by starting your platycodon indoors.

Last Frost Date

In Zone 4b the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Zone 4b is just an average the actual date of last frost changes from year to year. Since half of the time in Zone 4b it frosts late in the year after May 15 be ready to cover your platycodon in the event of a late frost.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.