Before planting it is a good idea to find your USDA Zone info to determine 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 Rosenberg you can estimate when it's the best time to plant onions by looking at 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.

Onions are one of those plants that can tolerate quite a bit of cold weather which means that you can plant them a quite a bit earlier than more sensitive plants.

The earliest that you can plant onions in Rosenberg is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant onions and expect a good harvest is probably October. If you wait any later than that and your onions may not have a chance to really do well. If you are starting your onions indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Rosenberg the average date of last frost happens on February 15. You should expect an average low temperature of 20°F in the coldest months of winter.

It's important to remember that USDA zone info for Rosenberg is not always accurate and the actual date of last frost changes from year to year. Since half of the time in Rosenberg last frost occurs after February 15 be ready to protect your onions in the event of a surprise late frost.

USDA Zone Info for Rosenberg

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Rosenberg

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