Riverside, CA · zone 9b · ~350 frost-free days
When to plant in Riverside: frost dates and zone 9b.
In Riverside, the typical last spring frost lands around Jan 10 and the first fall frost around Dec 26, giving you about 350 frost-free days. Cool-season crops go out before the last frost; warm-season crops wait until after it.
The 2026 windows
Sow dates for Riverside, keyed to your frost.
| Crop | Start indoors | Spring sow / set out | Fall sow |
|---|---|---|---|
| Tomato, slicing | Dec 6 to Feb 5 | Jan 17 to Mar 19 | — |
| Lettuce, leaf | — | Dec 3 to Jan 17 | Oct 12 to Dec 11 |
| Carrot | — | Dec 3 to Jan 5 | Sep 30 to Oct 26 |
| Bush Bean | — | Jan 10 to Mar 2 | Sep 11 to Oct 14 |
| Cucumber, slicing | — | Jan 17 to Apr 18 | Aug 25 to Sep 25 |
| Pepper, bell | Dec 15 to Feb 5 | Jan 26 to Mar 19 | — |
| Kale | Oct 22 to Nov 19 | Dec 3 to Dec 31 | Sep 25 to Nov 10 |
| Spinach | — | Nov 19 to Dec 31 | Oct 12 to Nov 30 |
Riverside sits in Zone 9b, but two gardens in the same city can be a week or two apart. The planner works from your ZIP code's frost dates, not the zone, so the dates land right for your block, not the metro average.
Build your Riverside garden plan.
Tell the free planner what you want to eat and who you're feeding. It returns plant counts, spacing, and frost-safe sow dates for ZIP 92501 in about 60 seconds.
Riverside planting questions
What planting zone is Riverside, CA?+
Riverside is in USDA hardiness zone 9b. Growing zone, gardening zone, and planting zone all mean the same thing: the USDA number, 9b here. It tells you what survives winter, not when to plant. Frost dates set your planting time, and the free planner uses your exact ZIP code's frost dates, which can differ by weeks across one metro.
When is the last frost date in Riverside?+
The typical last spring frost in Riverside, CA is around Jan 10. That is an average from local history, not a guarantee, so tender crops like tomatoes and peppers are safer with a week of buffer after it.
When is the first frost date in Riverside?+
The typical first fall frost in Riverside, CA arrives around Dec 26, closing a growing season of roughly 350 frost-free days. Count backward from it to find the last date a fall crop can still finish.
What can I plant now in Riverside?+
It depends on the date. Cool-season crops like lettuce, kale, and spinach go out weeks before the last frost; warm-season crops like tomatoes and peppers wait until after Jan 10. The table above shows each crop's window; the free planner turns your ZIP into an exact, dated calendar.