The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant hosta in Boulder can be estimated by checking out the USDA zone info.

Planting Calendar for Hosta

Frost tolerance for hosta:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant hosta just a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant hosta 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 hosta and expect a good harvest is probably September. Any later than that and your hosta may not have a chance to really do well. You can get started a few weeks earlier by starting your hosta indoors.

Last Frost Date

In Boulder the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Always keep in mind that USDA zone info for Boulder is not always accurate and the actual date of last frost changes from year to year. Since half of the time in Boulder last frost occurs after April 15 be ready to cover your hosta if you have 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.