One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant pampas grass in Helena can be figured out by checking out the USDA zone info.

Planting Calendar for Pampas Grass

Frost tolerance for pampas grass:	Not tolerant of frost.
When to plant:	After the last frost.

Since pampas grass are not cold tolerant it is necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant pampas grass in Helena is May. However, you really should wait until June if you don't want to take any chances.

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

Last Frost Date

On average all chance of frost has passed is on May 15 in Helena. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Helena may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Helena you get surprised by a frost after May 15 so make sure that you are ready to protect your pampas grass in the event of a surprise late frost.

USDA Zone Info for Helena

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 Helena

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