Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant armeria in Boulder should be estimated by referring to the USDA zone info.

Planting Calendar for Armeria

Frost tolerance for armeria:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

You can plant armeria earlier in the year because they do well in cold.

The earliest that you can plant armeria in Boulder is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant armeria and expect a good harvest is probably September. Any later than that and your armeria may not have a chance to fully mature. If you are starting your armeria indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Boulder the average date of last frost happens on April 15. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Boulder may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Boulder you get surprised by a frost after April 15 so make sure that you are prepared to protect your armeria if you have a late frost.

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.