When to Plant Begonias in Ontario, CA

One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Ontario you can determine when it's possible to plant begonias by looking at the USDA zone info.

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Planting Calendar for Begonias

Frost tolerance for begonias: Not tolerant of frost.
When to plant: After the last frost when the weather gets warmer.

It's not a good idea to plant begonias until after all chance of frost has passed because they do not do well in cold weather.

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

The earliest that you can plant begonias in Ontario 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 begonias and expect a good harvest is probably September. Any later than that and your begonias may not have a chance to really do well. You can get started a little bit earlier by starting your begonias indoors.

Last Frost Date

The average date of last frost is January 31 in Ontario. You can expect an average low temperature of 30°F in the coldest months of winter.

Remember that USDA zone info for Ontario may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Ontario you get surprised by a frost after January 31 so always be ready to cover your begonias if you have a surprise late frost.

USDA Zone Info for Ontario

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 Low30°F
Highest Expected Low35°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 Ontario

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