When to Plant Onions in Cornelius, OR

Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Cornelius you can figure out when you can plant onions by referring to the USDA zone info.


Planting Calendar for Onions

Frost tolerance for onions: Very tolerant of frost.
When to plant: Up to 7 weeks before last frost.

You can plant onions much earlier in the year because they are very cold tolerant.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant onions
Possibly ok, but a risky time to plant onions
Probably not a good time to plant onions

The earliest that you can plant onions in Cornelius 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 onions and expect a good harvest is probably September. If you wait any later than that and your onions may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your onions indoors.

Last Frost Date

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

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

USDA Zone Info for Cornelius

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 Low15°F
Highest Expected Low20°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 Cornelius

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