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.

The earliest that you can plant hollyhocks in Portland should be figured out by using the USDA zone info.

Planting Calendar for Hollyhocks

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

You can plant hollyhocks just a bit earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant hollyhocks 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 hollyhocks and expect a good harvest is probably September. Any later than that and your hollyhocks may not have a chance to grow to maturity. If you are starting your hollyhocks indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Since the USDA zone info for Portland is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Portland you get surprised by a frost after April 15 so always be ready to cover your hollyhocks in the event of a late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°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 -10°F.

Plants to Grow in Portland

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