One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant perilla in Helena should be figured out by reviewing the USDA zone info.

Planting Calendar for Perilla

Frost tolerance for perilla:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Perilla do not do well in cold weather which tells us that you must wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant perilla in Helena 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 really do well. You can get started a couple of weeks earlier by starting your perilla indoors.

Last Frost Date

In Helena the average date of last frost happens on March 15. It might get as low as 10°F during the coldest months of winter.

It's important to remember that USDA zone info for Helena is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Helena last frost occurs after March 15 so make sure that you are ready to cover your perilla if you have one of those late frosts.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

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

Plants to Grow in Helena

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