Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant tithonia in Sammamish should be determined by reviewing the USDA zone info.

Planting Calendar for Tithonia

Frost tolerance for tithonia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Tithonia are not cold tolerant which tells us that it is important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant tithonia in Sammamish 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 tithonia and expect a good harvest is probably August. If you wait any later than that and your tithonia may not have a chance to grow to maturity. You can get started a little bit earlier by starting your tithonia indoors.

Last Frost Date

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

Remember that USDA zone info for Sammamish is not always accurate and the actual date of last frost changes from year to year. Since half of the time in Sammamish it frosts late in the year after March 15 be ready to protect your tithonia if you have one of those late frosts.

USDA Zone Info for Sammamish

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 Sammamish

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