Riverside County, CA — Planting Guide
Riverside County is in USDA Zone 9b. The average last spring frost is February 24 and the first fall frost is December 4, giving you a growing season of approximately 284 days.
At an elevation of 1,206 ft, Riverside County receives approximately 15.5 in of rainfall annually. Summer highs average 102°F with winter lows around 47°F. The predominant soil type is Loam.
Based on 30 years of NOAA climate station data, the last frost date here varies by 75 days year to year — ranging from January 7 in warm years to March 22 in cold years. The growing season is trending shorter by about 12.87 days per decade. Riverside County scores 39/100 (Challenging) on the Microclimate Index.
🌡️ Zone
9b (25°F to 30°F min)
❄️ Last Frost
February 24
🍂 First Frost
December 4
📅 Growing Season
284 days
⛰️ Elevation
1,206 ft
🌧️ Annual Rainfall
15.5 in
Monthly Watering Calendar
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 3.5 in | 11 days | — | None |
| Feb | 3.6 in | 11 days | 0.7 in | Moderate |
| Mar | 2.2 in | 8 days | 2.1 in | High |
| Apr | 1.2 in | 4 days | 3.1 in | Critical |
| May | 0.4 in | 1 days | 3.9 in | Critical |
| Jun | 0.1 in | 1 days | 4.2 in | Critical |
| Jul | 0 in | 0 days | 4.3 in | Critical |
| Aug | 0 in | 0 days | 4.3 in | Critical |
| Sep | 0.2 in | 0 days | 4.1 in | Critical |
| Oct | 0.6 in | 3 days | 3.7 in | Critical |
| Nov | 1.5 in | 5 days | 2.8 in | High |
| Dec | 2.4 in | 8 days | — | None |
Annual total: 15.7 in. Gardens typically need ~1 inch of water per week during the growing season. Months marked "None" for extra water are outside the active growing season for your zone — most gardens are dormant and don't need irrigation during those months.
Riverside County Soil Profile
Soil Type
Loam
Soil pH
6.2-7.8
Drainage
Well Drained
Frost Risk Probability
Based on 30 years of NOAA weather station data from 3 stations
Beginners: Plant frost-sensitive crops (tomatoes, peppers, squash) after the "Safe" date on the left. Harvest or cover them before the "Protect by" date on the right. Hardy crops (lettuce, peas, kale) can go in the yellow transition zones.
How to read this table: "Conservative" means you're safe from frost 9 out of 10 years — best for beginners and frost-sensitive crops. "Average year" is the typical date. "Aggressive" means only 1 in 10 years is that warm — experienced gardeners with frost protection can try these dates.
| Planting Strategy | Last Spring Frost | First Fall Frost | Frost-Free Days |
|---|---|---|---|
| Conservative (safest) | Mar 22 | Dec 18 | 271 days |
| Cautious | Mar 1 | Dec 8 | 282 days |
| Average year | Feb 24 | Dec 4 | 283 days |
| Optimistic | Feb 3 | Nov 26 | 296 days |
| Aggressive (risky) | Jan 7 | Nov 10 | 307 days |
Not very — frost dates can vary by ±75 days year-to-year. Use the "Conservative" row in the table below, and keep row covers handy for surprise late frosts.
Yes — growing seasons are getting shorter here (about 12.9 days per decade). Use the "Conservative" dates and choose fast-maturing varieties.
Gardening Difficulty Score
Riverside County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Riverside County
Free expert help is closer than you think. Your county's cooperative extension office connects you with trained gardeners, soil testing labs, and local programs — all specific to Riverside County's climate and soil.
County Extension Office
Riverside County University of California Cooperative Extension Extension Office
Phone: 530-750-1200
Visit Extension Office Website →
Extension offices are run by land-grant universities and funded by the USDA. Their advice is free, research-based, and tailored to your county's specific conditions.
Master Gardener Program
Free gardening help from trained volunteers
Master Gardeners are community volunteers who complete 40–60 hours of university horticultural training. They answer gardening questions, diagnose plant problems, and offer workshops — all free.
Many extension offices run a Master Gardener hotline where you can call or email with photos of plant problems for free diagnosis.
Soil Testing
Available through your extension office
Before amending your soil, get it tested. Your extension office offers soil testing (typically $10–$25) that tells you exact pH, nutrient levels, and amendment recommendations specific to what you want to grow.
Services Available in Riverside County
Finding local nurseries & garden centers in Riverside County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Riverside County's soil and climate that big-box stores can't. Plants from local growers are typically hardier because they're already acclimated to your zone.
How to Find Them
Search for "nurseries near Riverside County CA" or "garden center Riverside County" on Google Maps. Also check with your extension office — they often maintain lists of reputable local nurseries and plant sales.
Community gardens & gardening groups
Community gardens are a great way to learn from experienced gardeners in your area, especially if you're limited on space. Search "community garden Riverside County CA" or check your extension office and local parks department. Facebook groups like "Riverside County Gardeners" or "California Gardening" are also excellent for local advice and plant swaps.
What to Plant After Your Harvest
After your first crops finish, use the remaining frost-free days to grow a second round.
Show 6 more succession options
Sunlight & Day Length
Monthly daylight hours and peak sun — critical for onion varieties, photoperiod-sensitive plants, and solar garden planning.
Longest Day
14.2 hours
Summer solstice daylight
Shortest Day
9.8 hours
Winter solstice daylight
Peak Sun Hours
12.9 hr/day peak (summer)
Peak sun hours (green dashed line below) account for cloud cover — this is the usable direct sunlight your garden actually receives. Most vegetables need 6+ peak sun hours.
Onion tip: Day-neutral onion varieties like Candy, Cabernet, and Sierra Blanca perform best in your day-length range.
View detailed monthly data
| Month | Daylight Hours | Peak Sun Hours | Day Length |
|---|---|---|---|
| January | 10 hr | 6 hr | Short day |
| February | 10.8 hr | 6.8 hr | Short day |
| March | 11.7 hr | 7.8 hr | Short day |
| April | 12.8 hr | 9.6 hr | Neutral |
| May | 13.8 hr | 10.6 hr | Neutral |
| June | 14.2 hr | 12.9 hr | Long day |
| July | 14 hr | 12.8 hr | Long day |
| August | 13.3 hr | 11.5 hr | Neutral |
| September | 12.2 hr | 10 hr | Neutral |
| October | 11.1 hr | 8.2 hr | Short day |
| November | 10.2 hr | 6.4 hr | Short day |
| December | 9.8 hr | 5.4 hr | Short day |
Peak sun hours factor in typical cloud cover — use these for solar panel and shade-planning calculations.
Soil Temperature & Composting Calendar
Monthly soil temps tell you when to plant warm-season crops, and when your compost pile is actively working.
Plant Warm Crops When
Soil reaches 60°F+
Soil warm enough from Apr through Nov.
Best Month to Compost
Apr
Microbial activity peaks when soil is warm.
Active Composting
12 months
Nearly year-round composting.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 52°F | 59°F | ♻️ Active | ~14 weeks |
| Feb | 53°F | 58°F | ♻️ Active | ~14 weeks |
| Mar | 57°F | 62°F | ♻️ Active | ~14 weeks |
| Apr | 66°F | 66°F | 🔥 Peak | ~8 weeks |
| May | 75°F | 73°F | 🔥 Peak | ~8 weeks |
| Jun | 86°F | 82°F | 🔥 Peak | ~8 weeks |
| Jul | 94°F | 88°F | 🔥 Peak | ~8 weeks |
| Aug | 95°F | 92°F | 🔥 Peak | ~8 weeks |
| Sep | 91°F | 86°F | 🔥 Peak | ~8 weeks |
| Oct | 77°F | 81°F | 🔥 Peak | ~8 weeks |
| Nov | 67°F | 71°F | 🔥 Peak | ~8 weeks |
| Dec | 54°F | 62°F | ♻️ Active | ~14 weeks |
Highlighted rows = soil 60°F+ (safe for warm-season transplants). Compost finishes fastest during peak activity months.
Pest & Disease Pressure in Riverside County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
Insect Pest Pressure
High — expect multiple pest generations. Preventative measures essential.
Disease Risk
Low disease risk — dry conditions reduce fungal problems.
Seasonal Risk
View 6 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | High | Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov |
| Whiteflies | High | Apr, May, Jun, Jul, Aug, Sep, Oct, Nov |
| Spider mites | High | May, Jun, Jul, Aug, Sep, Oct |
| Fire ants | High | Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov |
| Thrips | Moderate | Apr, May, Jun, Jul, Aug |
| Leaf miners | Low | Mar, Apr, May, Jun |
Organic pest management tips
- Use row covers on susceptible crops during peak pest months
- Apply neem oil preventatively every 7-14 days during active pest season
- Interplant with strong-scented herbs (basil, marigold) to confuse pests
- Hand-pick larger pests (beetles, caterpillars) in early morning when they're sluggish
- Practice crop rotation — never plant the same family in the same spot within 3 years
Cover Crops for Riverside County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Fall Cover Crops (4 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Austrian winter peas | Oct 12 | Feb 3 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Crimson clover | Oct 12 | Feb 10 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
| Daikon radish | Oct 6 | Feb 10 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Sep 21 | Feb 10 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
Spring Cover Crops (4 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Mar 5 | Oct 9 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Cowpeas (southern peas) | Mar 3 | Oct 9 | ✓ Yes | Excellent nitrogen fixer for warm climates, edible |
| Sorghum-sudan grass | Feb 26 | Sep 25 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Jan 24 | Sep 25 | ✓ Yes | Living mulch, fixes nitrogen, permanent ground cover |
Summer Cover Crops (1 options) — Fill gaps and suppress weeds between plantings
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Sunflowers | Mar 23 | Nov 6 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Wind & Microclimate
Wind dries soil, stresses plants, and affects frost patterns. Understanding your exposure helps with garden placement.
Seasonal Wind Speed
Spring: 11 mph Summer: 11 mph
Fall: 9 mph Winter: 9 mph
Prevailing wind: W. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
4.6/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Moderate
Some terrain variation (875 ft range). Garden on slopes or higher ground if possible to avoid late-season frost pockets.
Rainwater Harvesting Potential
How much water you can collect, when to collect it, and what size system you need for your garden.
Annual Collection
7,824 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
8 rain barrels (55 gal each)
For a typical 500 sq ft garden. Serious collectors: consider a 2,500 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Jan, Feb, Mar, Dec
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
May, Jun, Jul, Aug, Sep, Oct
Dry months when you'll rely on stored water — size your storage for this gap.
Rainwater collection tips for your area
- Your county receives approximately 15.7 inches of rain per year
- A 1,000 sq ft roof can collect roughly 7,824 gallons annually
- Rainwater harvesting is fully legal in your state
- In your dry climate, every drop counts — consider a larger cistern system
- Position collection tanks in shade to reduce evaporation and algae growth
Soil & Growing Conditions in Riverside County
Soil Type
Loam
Soil pH 6.2–7.8 · Well Drained drainage
Native soil is well-suited to most vegetables and herbs with regular compost additions.
Watering Needs
Drought stress: 9.5/10
Very high drought stress. Irrigation is critical for garden success. Focus on water-efficient techniques and drought-adapted crops.
Season Tips
284-day frost-free season
Your long season supports multiple successions and heat-demanding crops like melons, sweet potatoes, and peppers. Plant warm-season crops as soon as soil warms.
Free Garden Planner
Plan your entire garden season — organize planting dates, track what you're growing, and know exactly when to start seeds, transplant, and harvest.
Recommended for Your Garden
Reduce heat stress and sun scorch in hot climates with UV-stabilized shade cloth.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Get instant, accurate soil pH readings to fine-tune your amendments.
🥬 Vegetables to Grow in Riverside County
115 vegetables that grow well in Zone 9b with planting dates for Riverside County.
Show all 115 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Jan 27 | Feb 24 | Mar 3 | May 26 – Jun 30 | 80–100 |
| Amaranth | Jan 13 | Feb 24 | Mar 3 | Jun 2 – Jul 21 | 90–120 |
| Artichoke | — | — | Mar 10 | Jul 14 – Sep 22 | 120–180 |
| Arugula | Jan 27 | Feb 3 | Feb 24 | Mar 31 – Jun 2 | 30–50 |
| Asparagus | — | — | Mar 10 | — | 730–1095 |
| Beets | — | Feb 3 | — | Mar 31 – Apr 28 | 50–70 |
| Belgian Endive | Jan 27 | Feb 3 | Feb 24 | Jun 16 – Aug 11 | 110–150 |
| Bitter Melon | Jan 13 | Feb 24 | Mar 3 | May 5 – Jun 16 | 60–90 |
| Black Beans | — | Mar 3 | — | Jun 2 – Jul 21 | 90–120 |
| Bok Choy | Jan 27 | Feb 3 | Feb 24 | Apr 7 – May 12 | 40–60 |
| Broccoli | Jan 27 | Feb 3 | Feb 24 | Apr 28 – Jun 9 | 60–90 |
| Broccoli Rabe | Jan 27 | Feb 3 | Feb 24 | Apr 7 – May 12 | 40–60 |
| Brussels Sprouts | Jan 27 | Feb 3 | Feb 24 | May 26 – Jul 21 | 90–130 |
| Butternut Squash | Jan 27 | Feb 24 | Mar 3 | Jun 2 – Jul 7 | 85–110 |
| Cabbage | Jan 27 | Feb 3 | Feb 24 | Apr 28 – Jun 23 | 60–100 |
| Calabash | Jan 13 | Feb 24 | Mar 3 | May 26 – Jul 21 | 80–120 |
| Cardoon | — | — | Mar 10 | Jul 14 – Aug 25 | 120–150 |
| Carrots | — | Feb 3 | — | Apr 7 – May 12 | 60–80 |
| Cauliflower | Jan 27 | Feb 3 | Feb 24 | Apr 21 – Jun 23 | 55–100 |
| Celeriac | Jan 27 | Feb 3 | Feb 24 | Jun 9 – Jul 14 | 100–120 |
| Celery | Jan 27 | Feb 3 | Feb 24 | May 19 – Jul 14 | 80–120 |
| Celtuce | Jan 27 | Feb 3 | Feb 24 | Apr 28 – Jun 9 | 60–90 |
| Chard | Jan 27 | Feb 3 | Feb 24 | Apr 21 – Jun 9 | 50–60 |
| Chayote | Jan 13 | Feb 24 | Mar 3 | Jul 7 – Sep 15 | 120–180 |
| Chickpeas | Jan 27 | Feb 3 | Feb 24 | May 19 – Jun 30 | 80–110 |
| Chicory | Jan 27 | Feb 3 | Feb 24 | Apr 28 – Jun 9 | 60–85 |
| Chinese Cabbage | Jan 27 | Feb 3 | Feb 24 | Apr 21 – May 19 | 50–70 |
| Christmas Lima Beans | Jan 13 | Feb 24 | Mar 3 | May 26 – Jun 30 | 80–100 |
| Collard Greens | Jan 27 | Feb 3 | Feb 24 | Apr 21 – Jun 23 | 55–75 |
| Corn | — | Mar 3 | — | May 5 – Jun 30 | 60–100 |
| Cowpeas | — | Mar 3 | — | May 5 – Jun 16 | 60–90 |
| Cress | Jan 27 | Feb 3 | Feb 24 | Mar 10 – Mar 31 | 14–21 |
| Crookneck Squash | Jan 27 | Feb 24 | Mar 3 | Apr 21 – May 19 | 45–60 |
| Crosne | — | Feb 3 | — | Jul 7 – Sep 8 | 150–200 |
| Cucumber | Jan 27 | Feb 24 | Mar 3 | Apr 28 – Jun 23 | 50–70 |
| Daikon | — | Feb 3 | — | Mar 31 – Apr 28 | 50–70 |
| Delicata Squash | Jan 27 | Feb 24 | Mar 3 | May 26 – Jun 30 | 80–100 |
| Edamame | — | Mar 3 | — | May 19 – Jun 30 | 75–100 |
| Eggplant | Jan 13 | Feb 24 | Mar 3 | May 12 – Jul 14 | 65–85 |
| Endive | Jan 27 | Feb 3 | Feb 24 | Apr 14 – May 19 | 45–65 |
| Escarole | Jan 27 | Feb 3 | Feb 24 | Apr 21 – May 19 | 50–70 |
| Fava Beans | Jan 27 | Feb 3 | Feb 24 | May 12 – Jun 23 | 75–100 |
| Fennel | Jan 13 | Feb 24 | Mar 3 | May 5 – Jun 16 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Ginger | Jan 13 | Feb 24 | Mar 3 | Nov 3 – Dec 29 | 240–300 |
| Green Beans | — | Mar 3 | — | Apr 28 – Jun 23 | 50–65 |
| Horseradish | — | — | Mar 10 | Jul 14 – Sep 22 | 120–180 |
| Hot Peppers | Jan 13 | Feb 24 | Mar 3 | May 12 – Aug 18 | 70–120 |
| Hubbard Squash | Jan 27 | Feb 24 | Mar 3 | Jun 16 – Jul 21 | 100–120 |
| Jicama | Jan 13 | Feb 24 | Mar 3 | Jul 7 – Sep 15 | 120–180 |
| Kabocha | Jan 27 | Feb 24 | Mar 3 | Jun 2 – Jun 30 | 85–100 |
| Kai Lan | Jan 27 | Feb 3 | Feb 24 | Apr 14 – May 12 | 45–60 |
| Kale | Jan 27 | Feb 3 | Feb 24 | Apr 21 – Jun 16 | 50–70 |
| Kidney Beans | — | Mar 3 | — | Jun 2 – Jul 7 | 85–110 |
| Kohlrabi | Jan 27 | Feb 3 | Feb 24 | Apr 14 – May 19 | 45–65 |
| Komatsuna | Jan 27 | Feb 3 | Feb 24 | Mar 31 – May 5 | 35–50 |
| Leeks | Jan 27 | Feb 3 | Feb 24 | May 26 – Aug 11 | 90–150 |
| Lentils | Jan 27 | Feb 3 | Feb 24 | May 19 – Jun 30 | 80–110 |
| Lettuce | Jan 27 | Feb 3 | Feb 24 | Mar 31 – Jun 9 | 30–60 |
| Lima Beans | — | Mar 3 | — | May 5 – Jun 16 | 60–90 |
| Loofah | Jan 13 | Feb 24 | Mar 3 | Jun 16 – Aug 18 | 100–150 |
| Luffa | Jan 13 | Feb 24 | Mar 3 | Jun 2 – Aug 18 | 90–150 |
| Mache | Jan 27 | Feb 3 | Feb 24 | Apr 7 – May 12 | 40–60 |
| Malabar Spinach | Jan 13 | Feb 24 | Mar 3 | Apr 28 – May 26 | 55–70 |
| Melon | Jan 27 | Feb 24 | Mar 3 | May 12 – Jun 30 | 70–100 |
| Microgreens | Jan 27 | Feb 3 | Feb 24 | Mar 3 – Mar 31 | 7–21 |
| Mitsuba | Jan 27 | Feb 3 | Feb 17 | Apr 14 – Jun 9 | 50–70 |
| Mizuna | Jan 27 | Feb 3 | Feb 24 | Mar 31 – Apr 28 | 30–45 |
| Mustard Greens | Jan 27 | Feb 3 | Feb 24 | Mar 31 – Jun 2 | 30–50 |
| Napa Cabbage | Jan 27 | Feb 3 | Feb 24 | Apr 21 – May 26 | 55–75 |
| New Zealand Spinach | Jan 13 | Feb 24 | Mar 3 | Apr 28 – May 26 | 55–70 |
| Okra | Jan 13 | Feb 24 | Mar 3 | Apr 28 – Jun 23 | 50–65 |
| Onion | Jan 27 | Feb 3 | Feb 24 | May 26 – Jul 14 | 90–120 |
| Pac Choi | Jan 27 | Feb 3 | Feb 24 | Apr 7 – May 5 | 40–55 |
| Parsnip | — | Feb 3 | — | May 19 – Jun 30 | 100–130 |
| Patty Pan Squash | Jan 27 | Feb 24 | Mar 3 | Apr 21 – May 19 | 45–60 |
| Peas | Jan 27 | Feb 3 | Feb 24 | Apr 21 – Jun 16 | 55–70 |
| Peppers | Jan 13 | Feb 24 | Mar 3 | May 5 – Jul 14 | 60–90 |
| Pole Beans | Jan 13 | Feb 24 | Mar 3 | Apr 28 – Jun 23 | 55–70 |
| Potatoes | Jan 13 | Feb 24 | Mar 3 | May 12 – Jul 21 | 70–120 |
| Pumpkin | Jan 27 | Feb 24 | Mar 3 | Jun 2 – Jul 21 | 85–120 |
| Purslane | Jan 27 | Feb 3 | Feb 24 | Apr 7 – May 12 | 40–60 |
| Radicchio | Jan 27 | Feb 3 | Feb 24 | Apr 28 – Jun 2 | 60–80 |
| Radish | — | Feb 3 | — | Mar 3 – Mar 24 | 22–35 |
| Romanesco | Jan 27 | Feb 3 | Feb 24 | May 12 – Jun 23 | 75–100 |
| Rutabaga | — | Feb 3 | — | Apr 28 – Jun 2 | 80–100 |
| Salsify | — | Feb 3 | — | May 19 – Jun 30 | 100–130 |
| Savoy Cabbage | Jan 27 | Feb 3 | Feb 24 | May 5 – Jun 30 | 70–110 |
| Scallions | Jan 27 | Feb 3 | Feb 24 | Apr 21 – May 19 | 50–70 |
| Scarlet Runner Beans | Jan 13 | Feb 24 | Mar 3 | May 5 – Jun 9 | 60–80 |
| Shallot | Jan 27 | Feb 3 | Feb 24 | May 26 – Jul 14 | 90–120 |
| Shiso | Jan 13 | Mar 3 | Mar 3 | Apr 28 – Jun 23 | 50–70 |
| Snap Peas | Jan 13 | Feb 24 | Mar 3 | Apr 28 – Jun 23 | 55–70 |
| Snow Peas | Jan 27 | Feb 3 | Feb 24 | Apr 21 – Jun 16 | 50–65 |
| Soybeans | — | Mar 3 | — | May 26 – Jul 21 | 80–120 |
| Spaghetti Squash | Jan 27 | Feb 24 | Mar 3 | Jun 2 – Jun 30 | 85–100 |
| Spinach | Jan 27 | Feb 3 | Feb 24 | Mar 31 – Jun 2 | 35–50 |
| Squash (Summer) | Jan 27 | Feb 24 | Mar 3 | Apr 21 – Jun 23 | 45–65 |
| Squash (Winter) | Jan 27 | Feb 24 | Mar 3 | May 26 – Jul 21 | 80–120 |
| Sunchoke | — | — | Mar 10 | Jun 30 – Aug 25 | 110–150 |
| Sunflower | Jan 13 | Feb 24 | Mar 3 | May 12 – Jun 30 | 70–100 |
| Sweet Corn | — | Mar 3 | — | May 5 – Jun 16 | 60–90 |
| Sweet Potatoes | Jan 13 | Feb 24 | Mar 3 | Jun 2 – Jul 21 | 90–120 |
| Tatsoi | Jan 27 | Feb 3 | Feb 24 | Mar 31 – May 5 | 35–50 |
| Tomatillo | Jan 13 | Feb 24 | Mar 3 | May 5 – Jul 14 | 60–85 |
| Tomatoes | Jan 13 | Feb 24 | Mar 3 | May 5 – Jul 14 | 60–85 |
| Turmeric | Jan 13 | Feb 24 | Mar 3 | Nov 3 – Dec 29 | 240–300 |
| Turnip | — | Feb 3 | — | Mar 17 – Apr 21 | 40–60 |
| Watercress | Jan 27 | Feb 3 | Feb 24 | Apr 7 – May 12 | 40–60 |
| Watermelon | Jan 27 | Feb 24 | Mar 3 | May 12 – Jun 30 | 70–100 |
| Wax Beans | — | Mar 3 | — | Apr 28 – Jun 23 | 50–65 |
| Winter Melon | Jan 13 | Feb 24 | Mar 3 | Jun 2 – Jul 21 | 90–120 |
| Yam | Jan 13 | Feb 24 | Mar 3 | Sep 1 – Dec 29 | 180–330 |
| Yard Long Beans | Jan 13 | Feb 24 | Mar 3 | Apr 28 – Jun 9 | 55–80 |
| Zucchini | Jan 27 | Feb 24 | Mar 3 | Apr 21 – Jun 16 | 45–60 |
🍓 Fruits to Grow in Riverside County
24 fruits that grow well in Zone 9b with planting dates for Riverside County.
Show all 24 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Mar 10 | Jun 9 – Sep 22 | 90–180 |
| Blackberries | — | — | Mar 10 | — | 365–730 |
| Boysenberries | — | — | Mar 10 | — | 365–730 |
| Cantaloupe | — | — | Mar 10 | May 19 – Jun 23 | 70–90 |
| Che Fruit | — | — | Mar 10 | — | 1095–1825 |
| Dragon Fruit | — | — | Mar 10 | — | 365–730 |
| Elderberries | — | — | Mar 10 | — | 730–1095 |
| Figs | — | — | Mar 10 | — | 730–1825 |
| Goji Berries | — | — | Mar 10 | — | 730–1095 |
| Grapes | — | — | Mar 10 | — | 730–1095 |
| Ground Cherry | — | — | Mar 10 | May 19 – Jul 14 | 65–80 |
| Guava | — | — | Mar 10 | — | 365–730 |
| Honeydew | — | — | Mar 10 | Jun 2 – Jul 14 | 80–110 |
| Kiwi | — | — | Mar 10 | — | 1095–1825 |
| Loquat | — | — | Mar 10 | — | 730–1825 |
| Mulberries | — | — | Mar 10 | — | 730–1825 |
| Passion Fruit | — | — | Mar 10 | — | 365–545 |
| Pawpaw | — | — | Mar 10 | — | 1095–2555 |
| Persimmon | — | — | Mar 10 | — | 1095–2555 |
| Pomegranate | — | — | Mar 10 | — | 730–1095 |
| Quince | — | — | Mar 10 | — | 1095–1825 |
| Raspberries | — | — | Mar 10 | — | 365–730 |
| Serviceberries | — | — | Mar 10 | — | 730–1095 |
| Strawberries | — | — | Mar 10 | Jun 9 – Jan 5 | 90–365 |
🌿 Herbs to Grow in Riverside County
40 herbs that grow well in Zone 9b with planting dates for Riverside County.
Show all 40 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Anise | Jan 27 | Feb 3 | Feb 17 | May 19 – Aug 4 | 90–120 |
| Basil | Jan 13 | Mar 3 | Mar 3 | Apr 28 – Jun 30 | 50–75 |
| Bee Balm | — | — | Mar 3 | Jun 2 – Aug 18 | 90–120 |
| Borage | Jan 27 | Feb 3 | Feb 17 | Apr 14 – Jun 2 | 50–60 |
| Caraway | Jan 27 | Feb 3 | Feb 17 | — | 365–450 |
| Catnip | — | — | Mar 3 | May 5 – Jul 7 | 60–80 |
| Chamomile | Jan 27 | Feb 3 | Feb 17 | Apr 21 – Jun 30 | 60–90 |
| Chervil | Jan 27 | Feb 3 | Feb 17 | Mar 31 – Jun 2 | 40–60 |
| Chives | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Cilantro | Jan 27 | Feb 3 | Feb 17 | Mar 31 – Jun 2 | 40–60 |
| Comfrey | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Cumin | Jan 27 | Feb 3 | Feb 17 | Jun 2 – Aug 4 | 100–120 |
| Dill | Jan 27 | Feb 3 | Feb 17 | Mar 31 – Jun 2 | 40–60 |
| Echinacea | — | — | Mar 3 | Jul 7 – Oct 13 | 120–180 |
| Epazote | Jan 13 | Mar 3 | Mar 3 | Apr 21 – Jun 16 | 45–60 |
| Fennel (herb) | Jan 27 | Feb 3 | Feb 17 | Apr 21 – Jun 30 | 60–90 |
| Feverfew | — | — | Mar 3 | Jun 2 – Aug 18 | 90–120 |
| Garlic Chives | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Horehound | — | — | Mar 3 | May 19 – Jul 14 | 75–90 |
| Hyssop | — | — | Mar 3 | May 12 – Jul 14 | 70–90 |
| Lavender | — | — | Mar 3 | Jun 2 – Nov 3 | 90–200 |
| Lemon Balm | — | — | Mar 3 | May 5 – Jun 23 | 60–70 |
| Lemon Thyme | — | — | Mar 3 | May 12 – Jul 14 | 70–90 |
| Lemon Verbena | Jan 13 | Mar 3 | Mar 3 | May 5 – Jul 14 | 60–90 |
| Lemongrass | Jan 13 | Mar 3 | Mar 3 | May 19 – Aug 18 | 75–120 |
| Marjoram | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Mint | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Oregano | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Parsley | Jan 27 | Feb 3 | Feb 17 | Apr 21 – Jun 23 | 60–80 |
| Rosemary | — | — | Mar 3 | May 26 – Oct 13 | 80–180 |
| Rue | — | — | Mar 3 | May 12 – Jul 14 | 70–90 |
| Sage | — | — | Mar 3 | May 19 – Jul 14 | 75–90 |
| Savory | — | — | Mar 3 | Apr 28 – Jun 23 | 50–70 |
| Sorrel | Jan 27 | Feb 3 | Feb 17 | Mar 31 – Jun 2 | 40–60 |
| Stevia | Jan 13 | Mar 3 | Mar 3 | May 5 – Jul 14 | 60–90 |
| Tarragon | — | — | Mar 3 | May 5 – Jul 14 | 60–90 |
| Thai Basil | Jan 13 | Mar 3 | Mar 3 | Apr 28 – Jun 30 | 50–75 |
| Thyme | — | — | Mar 3 | May 12 – Jul 14 | 70–90 |
| Valerian | — | — | Mar 3 | Jul 7 – Oct 13 | 120–180 |
| Yarrow | — | — | Mar 3 | Jun 2 – Aug 18 | 90–120 |
Monthly Planting Guide for Riverside County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Riverside County.
Frequently Asked Questions
What planting zone is Riverside County, CA?
Riverside County is in USDA Hardiness Zone 9b. This zone classification determines which perennial plants survive winter and sets the baseline for frost timing across the county.
When is the last frost in Riverside County, CA?
Based on 30 years of NOAA weather station data, the median last spring frost in Riverside County falls around February 24. In 8 out of 10 years, last frost lands between January 7 and March 22 — a 75-day window of variability. Use March 22 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Riverside County, CA?
The median first fall frost in Riverside County arrives around December 4. In cold years it can arrive as early as November 10; in mild years as late as December 18. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Riverside County?
Riverside County has a frost-free growing season of approximately 284 days. This long season supports multiple succession plantings and warm-season crops that need extended heat, like sweet potatoes and melons. Climate records show the growing season is trending shorter by about 12.87 days per decade.
What is the soil like in Riverside County for gardening?
Riverside County has predominantly Loam soil with a pH range of 6.2–7.8 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Riverside County?
Riverside County has commercial agriculture that includes Lettuce, Strawberries, Broccoli. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Riverside County a good location for home gardening?
Riverside County scores 39/100 (Challenging) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. Gardening here benefits from close attention to frost timing and season extension due to the challenging microclimate factors.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Riverside County gardeners in Zone 9b organize planting dates, track what's growing, and never miss a planting window.
Get Your Free Garden Planner →Free download. Plan your entire garden season in minutes.
