Before planting it is a good idea to find your USDA Zone info to estimate 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.

A common way of figuring out when it's possible to plant onions is to refer to the USDA zone info for Delta.

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.

The earliest that you can plant onions in Delta 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. Starting your onions indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Delta. It might get as low as -5°F during the coldest months of winter.

Since the USDA zone info for Delta is just an average the actual date of last frost is different every year. Half of the time in Delta you get surprised by a frost after April 15 so make sure that you are ready to cover your onions in the event of one of those late frosts.

USDA Zone Info for Delta

Here is the info for USDA Zone 6b.

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

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

Plants to Grow in Delta

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