The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant perilla in Boulder can be figured out by referring to the USDA zone info.

Planting Calendar for Perilla

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

Perilla require warm weather which means that you need to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant perilla in Boulder 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 perilla and expect a good harvest is probably August. Any later than that and your perilla may not have a chance to fully mature. If you are starting your perilla 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 Boulder. You can expect an average low temperature of -15°F in the coldest months of winter.

It's important to remember that USDA zone info for Boulder is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Boulder it frosts late in the year after April 15 be ready to protect your perilla in the event of one of those late frosts.

USDA Zone Info for Boulder

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Boulder

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