One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to determine when it's possible to plant helianthemum by reviewing the USDA zone info for The Dalles.

Planting Calendar for Helianthemum

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

Helianthemum do well in moderate cold which tells us that you can plant them just a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant helianthemum in The Dalles 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. If you wait any later than that and your helianthemum may not have a chance to fully mature. You can get started a little bit earlier by starting your helianthemum indoors.

Last Frost Date

On average the last frost has passed is on March 15 in The Dalles. You can expect an average low temperature of 10°F in the coldest months of winter.

Since the USDA zone info for The Dalles may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in The Dalles you get a frost after March 15 be ready to protect your helianthemum if you have one of those late frosts.

USDA Zone Info for The Dalles

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in The Dalles

You may be interested in your other planting guides for The Dalles.