One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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.

A way of getting a good idea when you can plant zinnia is to use the USDA zone info for Troutdale.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Zinnia are not cold tolerant which means that it is important to 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 zinnia in Troutdale 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 zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your zinnia indoors.

Last Frost Date

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

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Troutdale and it can change quite a bit from year to year. Half of the time in Troutdale there is a last frost after March 15 so always be ready to protect your zinnia if you have one of those late frosts.

USDA Zone Info for Troutdale

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 Troutdale

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