When to plant onion in Fontana
Onion is cold-hardy, so every date keys off Fontana's frost dates.
Step 1 · Sow
Direct sow outdoors
Feb 19 – Mar 12
Sow straight into warm, workable soil.
Step 2 · Harvest
Harvest window
May 20 – Jun 9
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
From sowing to first pick.
Common questions
When can I sow onion outdoors in Fontana?
Direct-sow around mid February (Feb 19–Mar 12) in Fontana, based on its local frost dates. Confidence 75%.
When will onion be ready to harvest in Fontana?
Expect to harvest from around mid May (May 20–Jun 9) in Fontana, based on its local frost dates. Confidence 69%.
How long is the growing season in Fontana?
Fontana has roughly 365 frost-free days, which is enough time to grow onion to maturity outdoors.
The rule of thumb
Sow onion as soon as the soil is workable — it tolerates cool weather and light frost. Every date on this page is derived from that rule and Fontana's frost dates.
Confidence 77/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.