Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Portland can be reffered to in order to figure out when it's a good idea to plant alstromeria.

Planting Calendar for Alstromeria

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

Alstromeria tend to make it in some cold which tells us that you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant alstromeria 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 alstromeria and expect a good harvest is probably September. You probably don't want to wait any later than that or else your alstromeria may not have a chance to really do well. If you are starting your alstromeria indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on March 15 in Portland. In the coldest months of winter you can expect an average low temperature of 15°F.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Portland and it can change quite a bit from year to year. Half of the time in Portland it frosts late in the year after March 15 so make sure that you are prepared to protect your alstromeria in the event of a late frost.

USDA Zone Info for Portland

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 Portland

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