Frost Dates for Riverside, CA 92508
Riverside has 8 ZIP codes. The Riverside, CA frost page lists all of them with their dates.
Last spring frost January 26 · First fall frost December 23 · 331 frost-free days · USDA Zone 9b
ZIP 92508 has about 36,900 people, one of 8 ZIP codes in Riverside.
Very long season: 331 frost-free days.
Frost probability for 92508
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | March 7 | January 26 | — |
| Fall (first frost) | November 18 | December 23 | — |
Dates come from NOAA 1971–2000 freeze probabilities at RIVERSIDE FIRE STN 3 (8.7 km away); the 50% date is the median year.
Which crops fit a 331-day season in Riverside
In Riverside (331 frost-free days, a very long season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Dec 22 | Feb 9–Feb 16 | 289 | fits: 80 days to maturity, 289 available after Feb 9. | Aug 23 |
| Pepper | Dec 15 | Feb 9–Feb 16 | 289 | fits: 75 days to maturity, 289 available after Feb 9. | Aug 28 |
| Lettuce | Dec 1 | Dec 29–Jan 5 | 366 | two-plantings: Plant Dec 29 and again by Nov 1; both mature before Dec 30. | Nov 1 |
| Carrots | — | Jan 5–Jan 12 | 373 | fits: 70 days to maturity, 373 available after Jan 5. | Oct 21 |
| Cucumber | Jan 5 | Feb 9–Feb 16 | 303 | two-plantings: Plant Feb 9 and again by Sep 26; both mature before Dec 9. | Sep 26 |
| Beans | — | Feb 2–Feb 16 | 317 | two-plantings: Plant Feb 2 and again by Oct 3; both mature before Dec 16. | Oct 3 |
| Peas | — | Dec 1–Feb 9 | 394 | fits: 65 days to maturity, 394 available after Dec 1. | Oct 12 |
| Zucchini | Jan 12 | Feb 9–Feb 16 | 303 | two-plantings: Plant Feb 9 and again by Oct 1; both mature before Dec 9. | Oct 1 |
| Onion | Nov 3 | Dec 29–Jan 12 | 366 | fits: 100 days to maturity, 366 available after Dec 29. | — |
| Spinach | — | Dec 1–Jan 19 | 408 | two-plantings: Plant Dec 1 and again by Nov 20; both mature before Jan 13. | Nov 20 |
| Kale | Nov 17 | Dec 29–Jan 12 | 380 | two-plantings: Plant Dec 29 and again by Nov 5; both mature before Jan 13. | Nov 5 |
| Broccoli | Dec 1 | Dec 29–Jan 12 | 366 | fits: 80 days to maturity, 366 available after Dec 29. | Sep 27 |
| Cabbage | Dec 1 | Dec 29–Jan 12 | 380 | fits: 70 days to maturity, 380 available after Dec 29. | Oct 21 |
| Radish | — | Dec 1–Feb 23 | 394 | two-plantings: Plant Dec 1 and again by Nov 21; both mature before Dec 30. | Nov 21 |
| Beets | — | Dec 1–Feb 23 | 394 | two-plantings: Plant Dec 1 and again by Oct 22; both mature before Dec 30. | Oct 22 |
| Potatoes | — | Jan 12–Jan 19 | 352 | fits: 90 days to maturity, 352 available after Jan 12. | — |
| Garlic | — | Dec 23 | 436 | overwinter: Plant Dec 23 to Jan 13; harvest the following summer. | Jan 13 |
| Strawberry | — | Dec 22–Feb 16 | 387 | perennial: A perennial: plant Dec 22; it fruits from the following year and keeps producing for several years. | — |
| Corn | Dec 29 | Feb 2–Feb 9 | 303 | fits: 75 days to maturity, 303 available after Feb 2. | Sep 4 |
| Pumpkin | Jan 12 | Feb 9–Feb 9 | 296 | fits: 100 days to maturity, 296 available after Feb 9. | Aug 10 |
| Cauliflower | Dec 15 | Jan 19–Feb 2 | 345 | fits: 75 days to maturity, 345 available after Jan 19. | Oct 2 |
| Swiss Chard | Dec 1 | Jan 12–Jan 12 | 352 | two-plantings: Plant Jan 12 and again by Oct 22; both mature before Dec 30. | Oct 22 |
| Arugula | — | Dec 1–Feb 23 | 408 | two-plantings: Plant Dec 1 and again by Nov 20; both mature before Jan 13. | Nov 20 |
| Brussel Sprouts | Dec 1 | Dec 29–Jan 12 | 380 | fits: 100 days to maturity, 380 available after Dec 29. | Sep 21 |
| Butternut Squash | Jan 12 | Feb 9–Feb 16 | 296 | fits: 100 days to maturity, 296 available after Feb 9. | Aug 10 |
| Eggplant | Dec 8 | Feb 9–Feb 16 | 289 | fits: 70 days to maturity, 289 available after Feb 9. | Sep 2 |
| Okra | Dec 29 | Feb 2–Feb 9 | 310 | two-plantings: Plant Feb 2 and again by Oct 1; both mature before Dec 9. | Oct 1 |
| Basil | Dec 22 | Feb 16–Feb 16 | 296 | two-plantings: Plant Feb 16 and again by Sep 26; both mature before Dec 9. | Sep 26 |
| Cilantro | — | Dec 29–Jan 19 | 366 | two-plantings: Plant Dec 29 and again by Oct 27; both mature before Dec 30. | Oct 27 |
| Parsley | Nov 17 | Feb 2–Feb 9 | 331 | fits: 70 days to maturity, 331 available after Feb 2. | Oct 7 |
| Celery | Nov 17 | Feb 2–Feb 16 | 331 | fits: 120 days to maturity, 331 available after Feb 2. | Aug 18 |
| Scallions | Nov 17 | Dec 29–Jan 12 | 380 | two-plantings: Plant Dec 29 and again by Oct 31; both mature before Jan 13. | Oct 31 |
| Turnip | — | Dec 29–Jan 12 | 380 | two-plantings: Plant Dec 29 and again by Nov 10; both mature before Jan 13. | Nov 10 |
| Kohlrabi | — | Dec 15–Dec 29 | 394 | two-plantings: Plant Dec 15 and again by Nov 5; both mature before Jan 13. | Nov 5 |
| Bok Choy | Dec 29 | Jan 19–Jan 26 | 345 | two-plantings: Plant Jan 19 and again by Nov 1; both mature before Dec 30. | Nov 1 |
| Collards | Nov 17 | Dec 29–Jan 12 | 380 | two-plantings: Plant Dec 29 and again by Oct 31; both mature before Jan 13. | Oct 31 |
| Cantaloupe | Jan 12 | Feb 9–Feb 16 | 289 | fits: 85 days to maturity, 289 available after Feb 9. | Aug 18 |
| Chives | Nov 3 | Feb 2–Feb 9 | 345 | fits: 90 days to maturity, 345 available after Feb 2. | — |
| Dill | — | Dec 1–Feb 23 | 394 | two-plantings: Plant Dec 1 and again by Oct 22; both mature before Dec 30. | Oct 22 |
| Oregano | Nov 17 | Feb 2–Feb 9 | 345 | fits: 80 days to maturity, 345 available after Feb 2. | — |
| Rosemary | Nov 3 | Feb 2–Feb 9 | 331 | fits: 80 days to maturity, 331 available after Feb 2. | — |
| Sage | Dec 1 | Feb 2–Feb 9 | 345 | fits: 75 days to maturity, 345 available after Feb 2. | — |
| Thyme | Nov 17 | Feb 2–Feb 9 | 345 | fits: 90 days to maturity, 345 available after Feb 2. | — |
| Calendula | Dec 15 | Jan 12–Jan 26 | 352 | two-plantings: Plant Jan 12 and again by Oct 27; both mature before Dec 30. | Oct 27 |
| Cosmos | Dec 29 | Jan 26–Feb 9 | 317 | two-plantings: Plant Jan 26 and again by Sep 26; both mature before Dec 9. | Sep 26 |
| Lavender | Nov 3 | Jan 26–Feb 9 | 352 | fits: 90 days to maturity, 352 available after Jan 26. | — |
| Marigolds | Dec 15 | Jan 26–Feb 2 | 317 | two-plantings: Plant Jan 26 and again by Oct 6; both mature before Dec 9. | Oct 6 |
| Melons | Jan 12 | Feb 9–Feb 16 | 289 | fits: 85 days to maturity, 289 available after Feb 9. | Aug 18 |
| Mint | — | Jan 26–Feb 9 | 352 | fits: 90 days to maturity, 352 available after Jan 26. | — |
| Nasturtiums | Dec 29 | Jan 26–Feb 2 | 317 | two-plantings: Plant Jan 26 and again by Oct 1; both mature before Dec 9. | Oct 1 |
| Pole Beans | — | Feb 2–Feb 16 | 310 | fits: 65 days to maturity, 310 available after Feb 2. | Sep 21 |
| Spaghetti Squash | Jan 12 | Feb 9–Feb 16 | 296 | fits: 90 days to maturity, 296 available after Feb 9. | Aug 20 |
| Sunflowers | — | Jan 26–Feb 9 | 317 | fits: 70 days to maturity, 317 available after Jan 26. | Sep 16 |
| Tomatillos | Dec 1 | Feb 2–Feb 9 | 296 | fits: 75 days to maturity, 296 available after Feb 2. | Aug 28 |
| Watermelon | Jan 12 | Feb 2–Feb 9 | 296 | fits: 80 days to maturity, 296 available after Feb 2. | Aug 23 |
| Yellow Squash | Jan 12 | Feb 9–Feb 16 | 303 | two-plantings: Plant Feb 9 and again by Oct 1; both mature before Dec 9. | Oct 1 |
| Zinnias | Dec 29 | Jan 26–Feb 9 | 317 | two-plantings: Plant Jan 26 and again by Sep 26; both mature before Dec 9. | Sep 26 |
Month by month in Riverside
| Month | What to do |
|---|---|
| January | Start indoors: Cucumber (Jan 5), Butternut Squash (Jan 12), Cantaloupe (Jan 12), Melons (Jan 12), Pumpkin (Jan 12), Spaghetti Squash (Jan 12), +3 more. Direct sow from: Carrots (Jan 5), Potatoes (Jan 12), Sunflowers (Jan 26). Transplant from: Calendula (Jan 12), Swiss Chard (Jan 12), Bok Choy (Jan 19), Cauliflower (Jan 19), Cosmos (Jan 26), Lavender (Jan 26), +4 more. Last frost around January 26. Last sowing dates: Garlic (Jan 13). |
| February | Direct sow from: Beans (Feb 2), Pole Beans (Feb 2). Transplant from: Celery (Feb 2), Chives (Feb 2), Corn (Feb 2), Okra (Feb 2), Oregano (Feb 2), Parsley (Feb 2), +17 more. |
| March | Succession plant lettuce and greens. Keep beds weeded and watered consistently. |
| April | Harvest regularly to encourage production. Monitor for pests and disease. |
| May | Midsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall. |
| June | Direct sow carrots and beets for fall harvest. Start fall broccoli and kale indoors. |
| July | Direct sow carrots and beets for fall harvest. Start fall broccoli and kale indoors. |
| August | Last sowing dates: Butternut Squash (Aug 10), Pumpkin (Aug 10), Cantaloupe (Aug 18), Celery (Aug 18), Melons (Aug 18), Spaghetti Squash (Aug 20), +4 more. |
| September | Last sowing dates: Eggplant (Sep 2), Corn (Sep 4), Sunflowers (Sep 16), Brussel Sprouts (Sep 21), Pole Beans (Sep 21), Basil (Sep 26), +4 more. |
| October | Last sowing dates: Nasturtiums (Oct 1), Okra (Oct 1), Yellow Squash (Oct 1), Zucchini (Oct 1), Cauliflower (Oct 2), Beans (Oct 3), +12 more. |
| November | Start indoors: Chives (Nov 3), Lavender (Nov 3), Onion (Nov 3), Rosemary (Nov 3), Celery (Nov 17), Collards (Nov 17), +5 more. Last sowing dates: Bok Choy (Nov 1), Lettuce (Nov 1), Kale (Nov 5), Kohlrabi (Nov 5), Turnip (Nov 10), Arugula (Nov 20), +2 more. |
| December | Start indoors: Broccoli (Dec 1), Brussel Sprouts (Dec 1), Cabbage (Dec 1), Lettuce (Dec 1), Sage (Dec 1), Swiss Chard (Dec 1), +14 more. Direct sow from: Arugula (Dec 1), Beets (Dec 1), Dill (Dec 1), Peas (Dec 1), Radish (Dec 1), Spinach (Dec 1), +4 more. Transplant from: Broccoli (Dec 29), Brussel Sprouts (Dec 29), Cabbage (Dec 29), Collards (Dec 29), Kale (Dec 29), Lettuce (Dec 29), +2 more. Plant: Strawberry (Dec 22). First frost around December 23. |
Frequently Asked Questions
What is the last frost date for Riverside, CA (ZIP 92508)?
The median last spring frost date for Riverside, CA (ZIP code 92508) is around January 26. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.
What is the first fall frost date in Riverside, CA?
The median first fall frost date for Riverside, CA is around December 23. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around November 18 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Riverside, CA?
The frost-free growing season in Riverside is about 331 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Riverside (331 frost-free days, a very long season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Riverside, CA?
Riverside, CA is in USDA hardiness zone 9b (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Riverside, CA?
Start tomatoes indoors Dec 22 and plant out Feb 9 in Riverside. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Riverside?
Two: plant Dec 29 and again by Nov 1; both mature before Dec 30.
When do I plant garlic in Riverside?
Dec 23 to Jan 13; it overwinters and is ready the following summer.
Can I get two tomato crops in Riverside?
Yes: plant out Feb 9 for a summer crop, and set out a second round of transplants by Aug 23 for a fall crop.
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- When to plant in Riverside, CA: month-by-month guide
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