One of the first steps you take when you are figuring out 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 USDA zone info for Umatilla can be reviewed to figure out when it's a good idea to plant helianthemum.

Planting Calendar for Helianthemum

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

Helianthemum do ok in some cold which means that you can plant them a little bit earlier in the year than more sensitive plants.

The earliest that you can plant helianthemum 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 helianthemum and expect a good harvest is probably September. You probably don't want to wait any later than that or else your helianthemum may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your helianthemum indoors.

Last Frost Date

On average the last frost is on April 15 in Umatilla. It might get as low as 5°F during the coldest months of winter.

Since the USDA zone info for Umatilla is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Umatilla last frost occurs after April 15 be ready to cover your helianthemum if you have a late frost.

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.