One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to determine when it's possible to plant lithospermum by referring to the USDA zone info for Snoqualmie.

Planting Calendar for Lithospermum

Frost tolerance for lithospermum:	Not tolerant of frost.
When to plant:	After the last frost.

Lithospermum require warm weather which tells us that you really should wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant lithospermum in Snoqualmie is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant lithospermum and expect a good harvest is probably August. If you wait any later than that and your lithospermum may not have a chance to fully mature. Starting your lithospermum indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is March 15 in Snoqualmie. You can expect an average low temperature of 15°F in the coldest months of winter.

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

USDA Zone Info for Snoqualmie

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Snoqualmie

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