One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. 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 Scappoose can be looked at to estimate when to plant tree onions.

Planting Calendar for Tree onions

Frost tolerance for tree onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant tree onions just a tiny bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant tree onions in Scappoose 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 tree onions and expect a good harvest is probably August. Any later than that and your tree onions may not have a chance to fully mature. Starting your tree onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Scappoose. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Scappoose is just an average the actual date of last frost changes from year to year. Half of the time in Scappoose you get surprised by a frost after March 15 so make sure that you are prepared to cover your tree onions in the event of a late frost.

USDA Zone Info for Scappoose

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 Scappoose

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