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.

A common way of making a decision about when to plant catharanthus is to use the USDA zone info for Portland.

Planting Calendar for Catharanthus

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

Since catharanthus do not do well in cold weather it is necessary to wait until after the last frost has passed before you can plant them.

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

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

Last Frost Date

In Portland the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Portland and it is different every year. Since half of the time in Portland you get surprised by a frost after February 15 be ready to protect your catharanthus in the event of a surprise late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in Portland

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