Use this planting calendar to find the best times of the year to grow fruits, vegetables, herbs, flowers, and other popular plants in Ontario, CA, based on the USDA Hardiness Zone 10a.
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Ontario, CA Frost Dates & Growing Season
Last Spring Frost Date for Ontario, CA
The average last frost date in spring for Ontario is February 1st. For gardeners planting sensitive crops like tomatoes, peppers, and basil, it is generally recommended to wait until February 15th before moving plants outdoors. Waiting these extra few weeks significantly reduces the risk of a late freeze damaging young transplants.
First Fall Frost Date for Ontario, CA
The average first frost date in fall for Ontario is December 15th. This date marks the approximate end of the growing season for tender plants. Gardeners should plan to harvest frost-sensitive vegetables or provide heavy protection (such as row covers) before this date to avoid crop loss.
Growing Season Length in Ontario, CA
Based on historical frost data, the estimated growing season length in Ontario is approximately 317 days. This duration determines which vegetable varieties have enough time to reach maturity before the winter cold sets in. Short-season varieties are recommended for crops that require a longer warm period.
Please note: These dates are climatological averages. Actual weather conditions vary by year. Always check the local 10-day forecast before planting.
Ontario, CA Planting Calendar
This weekly planting calendar displays the ideal windows for starting seeds, transplanting, and harvesting your plants.
Ontario, CA Monthly Planting Recommendations
January
In January, recommended activities include direct sowing Mustard (from January 4th to January 18th), direct sowing Lettuce (from January 4th to January 18th), and direct sowing Alyssum (from January 18th to February 1st).
February
In February, recommended activities include direct sowing Zucchini (from February 8th to February 22nd), direct sowing Pumpkin (from February 8th to February 22nd), and direct sowing Okra (from February 15th to March 1st).
November
In November, recommended activities include starting Petunia seeds indoors (from November 23rd to December 7th), starting Impatiens seeds indoors (from November 23rd to December 7th), and starting Geranium seeds indoors (from November 23rd to December 7th).
December
In December, recommended activities include starting Statice seeds indoors (from December 7th to December 21st), starting Black Eyed Susan seeds indoors (from December 7th to December 21st), and direct sowing Spinach (from December 21st to January 4th).