When to Plant Geranium in Ontario, CA

One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Ontario should be reffered to in order to determine when it's a good idea to plant geranium.


Planting Calendar for Geranium

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

Since geranium do not do well in cold weather you need to wait until after all chance of frost has passed before you can plant them.

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

The earliest that you can plant geranium 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 geranium and expect a good harvest is probably September. Any later than that and your geranium may not have a chance to fully mature. Starting your geranium indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is January 31 in Ontario. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Ontario is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Ontario you get surprised by a frost after January 31 so be sure to be ready to cover your geranium if you have a 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.