One of the first steps you take when you are determining 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.

In Umatilla you can figure out when it's the best time to plant asters by using the USDA zone info.

Planting Calendar for Asters

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

Asters are moderately cold tolerant which tells us that you can plant them a little bit earlier than more sensitive plants.

The earliest that you can plant asters in Umatilla 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 asters and expect a good harvest is probably September. You probably don't want to wait any later than that or else your asters may not have a chance to grow to maturity. If you are starting your asters indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Umatilla the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of 5°F.

Always keep in mind that USDA zone info for Umatilla is an average and the actual date of last frost changes from year to year. Since half of the time in Umatilla last frost occurs after April 15 be ready to cover your asters if you have one of those late frosts.

USDA Zone Info for Umatilla

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Umatilla

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