One of the best tools that you have as gardeners to help us figure out 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.

A way of determining when it's possible to plant sweet williams is to consult the USDA zone info for Portland.

Planting Calendar for Sweet Williams

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

You can plant sweet williams a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant sweet williams in Portland 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 sweet williams and expect a good harvest is probably September. You probably don't want to wait any later than that or else your sweet williams may not have a chance to grow to maturity. Starting your sweet williams indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Portland. In the coldest months of winter you can expect an average low temperature of 0°F.

Always keep in mind that USDA zone info for Portland is an average and the actual date of last frost changes from year to year. Since half of the time in Portland last frost occurs after April 15 be ready to protect your sweet williams in the event of a surprise late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Portland

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