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.

It's a good idea to determine when you can plant onions by referring to the USDA zone info for Monrovia.

Planting Calendar for Onions

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

Onions are very cold tolerant which tells us that you can plant them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant onions in Monrovia 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. Any later than that and your onions may not have a chance to fully mature. You can get started a little bit earlier by starting your onions indoors.

Last Frost Date

On average the last frost is on January 31 in Monrovia. You should expect an average low temperature of 30°F in the coldest months of winter.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Monrovia and it changes from year to year. Half of the time in Monrovia you get surprised by a frost after January 31 so always be ready to protect your onions if you have a surprise late frost.

USDA Zone Info for Monrovia

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Monrovia

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