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.

The best time to plant four o' clock in Helena should be estimated by using the USDA zone info.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After the last frost.

You should not plant four o' clock until after the last frost because they are not cold tolerant.

The earliest that you can plant four o' clock 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 four o' clock and expect a good harvest is probably August. Any later than that and your four o' clock may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your four o' clock indoors.

Last Frost Date

In Helena the average date of last frost happens on March 15. You can expect an average low temperature of 10°F in the coldest months of winter.

Remember that USDA zone info for Helena may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Helena it frosts late in the year after March 15 so make sure that you are prepared to protect your four o' clock in the event of 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.