Benton County, OR — Planting Guide
Benton County is in USDA Zone 8a. The average last spring frost is April 14 and the first fall frost is October 30, giving you a growing season of approximately 199 days.
At an elevation of 97 ft, Benton County receives approximately 53.1 in of rainfall annually. Summer highs average 85°F with winter lows around 43°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 63 days year to year — ranging from March 4 in warm years to May 7 in cold years. The growing season is trending shorter by about 5.02 days per decade. Benton County scores 55/100 (Moderate) on the Microclimate Index.
🌡️ Zone
8a (10°F to 15°F min)
❄️ Last Frost
April 14
🍂 First Frost
October 30
📅 Growing Season
199 days
⛰️ Elevation
97 ft
🌧️ Annual Rainfall
53.1 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 | 8.1 in | 15 days | — | None |
| Feb | 6.1 in | 14 days | — | Low |
| Mar | 5.8 in | 16 days | — | Low |
| Apr | 3.6 in | 14 days | 0.7 in | Moderate |
| May | 3.3 in | 9 days | 1 in | Moderate |
| Jun | 1.9 in | 6 days | 2.4 in | High |
| Jul | 0.9 in | 2 days | 3.4 in | Critical |
| Aug | 0.8 in | 3 days | 3.5 in | Critical |
| Sep | 2.3 in | 4 days | 2 in | High |
| Oct | 3.8 in | 10 days | 0.5 in | Low |
| Nov | 8.3 in | 15 days | — | Low |
| Dec | 8.2 in | 19 days | — | None |
Annual total: 53.1 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.
Benton County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.2
Drainage
Well Drained
Frost Risk Probability
Based on 31 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) | May 7 | Nov 29 | 206 days |
| Cautious | Apr 22 | Nov 8 | 200 days |
| Average year | Apr 14 | Oct 30 | 199 days |
| Optimistic | Mar 27 | Oct 24 | 211 days |
| Aggressive (risky) | Mar 4 | Oct 10 | 220 days |
Not very — frost dates can vary by ±63 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 5 days per decade). Use the "Conservative" dates and choose fast-maturing varieties.
Gardening Difficulty Score
Benton County presents some gardening challenges. Choose adapted varieties and plan around frost dates.
Local Gardening Help in Benton 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 Benton County's climate and soil.
County Extension Office
Benton County Oregon State University Extension Extension Office
Phone: 541-737-2713
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 Benton County
Finding local nurseries & garden centers in Benton County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Benton 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 Benton County OR" or "garden center Benton 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 Benton County OR" or check your extension office and local parks department. Facebook groups like "Benton County Gardeners" or "Oregon 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
15.3 hours
Summer solstice daylight
Shortest Day
8.7 hours
Winter solstice daylight
Peak Sun Hours
10.2 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: Your long summer days (14+ hours) support long-day onion varieties like Walla Walla, Sweet Spanish, and Ailsa Craig.
View detailed monthly data
| Month | Daylight Hours | Peak Sun Hours | Day Length |
|---|---|---|---|
| January | 9 hr | 2.3 hr | Short day |
| February | 10.2 hr | 2.9 hr | Short day |
| March | 11.6 hr | 4.1 hr | Short day |
| April | 13.2 hr | 5.4 hr | Neutral |
| May | 14.6 hr | 7.5 hr | Long day |
| June | 15.3 hr | 8.6 hr | Long day |
| July | 15 hr | 10.2 hr | Long day |
| August | 13.9 hr | 9.9 hr | Neutral |
| September | 12.3 hr | 7.3 hr | Neutral |
| October | 10.7 hr | 4 hr | Short day |
| November | 9.3 hr | 2.2 hr | Short day |
| December | 8.7 hr | 1.8 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 May through Oct.
Best Month to Compost
May
Microbial activity peaks when soil is warm.
Active Composting
9 months
Nearly year-round composting.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 45°F | 49°F | 🐢 Slow | ~24 weeks |
| Feb | 45°F | 49°F | 🐢 Slow | ~24 weeks |
| Mar | 53°F | 54°F | ♻️ Active | ~14 weeks |
| Apr | 60°F | 62°F | ♻️ Active | ~14 weeks |
| May | 72°F | 68°F | 🔥 Peak | ~8 weeks |
| Jun | 80°F | 75°F | 🔥 Peak | ~8 weeks |
| Jul | 89°F | 83°F | 🔥 Peak | ~8 weeks |
| Aug | 88°F | 86°F | 🔥 Peak | ~8 weeks |
| Sep | 86°F | 82°F | 🔥 Peak | ~8 weeks |
| Oct | 71°F | 75°F | 🔥 Peak | ~8 weeks |
| Nov | 60°F | 64°F | ♻️ Active | ~14 weeks |
| Dec | 49°F | 57°F | 🐢 Slow | ~24 weeks |
Highlighted rows = soil 60°F+ (safe for warm-season transplants). Compost finishes fastest during peak activity months.
Pest & Disease Pressure in Benton 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
High fungal/bacterial risk. Space plants for airflow, water at soil level.
Seasonal Risk
View 6 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | High | Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov |
| Squash vine borers | Moderate | May, Jun, Jul |
| Stink bugs | High | Apr, May, Jun, Jul, Aug, Sep, Oct |
| Whiteflies | High | May, Jun, Jul, Aug, Sep, Oct |
| Spider mites | Moderate | Jun, Jul, Aug, Sep |
| Fire ants | Moderate | Mar, Apr, May, Jun, Jul, Aug, Sep, Oct |
Organic pest management tips
- Install physical barriers: floating row covers, copper tape for slugs, mesh netting
- Apply Bt (Bacillus thuringiensis) for caterpillar control — safe for beneficial insects
- Use kaolin clay spray to deter a wide range of insects on fruiting crops
- Release beneficial insects: ladybugs for aphids, parasitic wasps for caterpillars
- Apply neem oil weekly during high-pressure months
- Mulch heavily (3-4 inches) to reduce soil-borne disease splash
Cover Crops for Benton County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Fall Cover Crops (7 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Austrian winter peas | Sep 2 | Mar 31 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Crimson clover | Sep 6 | Mar 31 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
| Daikon radish | Sep 3 | Mar 24 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Aug 7 | Mar 31 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Oct 1 | Mar 24 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 24 | Mar 24 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jul 22 | Mar 31 | — | Erosion control, weed suppression, good biomass |
Spring Cover Crops (4 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Apr 19 | Aug 21 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Cowpeas (southern peas) | Apr 19 | Sep 4 | ✓ Yes | Excellent nitrogen fixer for warm climates, edible |
| Sorghum-sudan grass | Apr 19 | Aug 21 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Mar 16 | Aug 28 | ✓ 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 | May 12 | Oct 2 | — | 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: 13 mph Summer: 8 mph
Fall: 10 mph Winter: 12 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5.3/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Moderate
Some terrain variation (775 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
26,465 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
6 rain barrels (55 gal each)
For a typical 500 sq ft garden. Serious collectors: consider a 2,000 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Jan, Feb, Nov, Dec
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Jul, Aug
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 53.1 inches of rain per year
- A 1,000 sq ft roof can collect roughly 26,465 gallons annually
- Rainwater harvesting is fully legal in your state
- Your area gets ample rainfall — even small barrels make a big difference
- Consider a rain garden to handle overflow during heavy rainfall months
Soil & Growing Conditions in Benton County
Soil Type
Silt Loam
Soil pH 5.6–6.2 · Well Drained drainage
Native soil is well-suited to most vegetables and herbs with regular compost additions.
Watering Needs
Drought stress: 3.5/10
Low-to-moderate drought stress. Plan to water 1–2 times per week during peak summer. (53.1 in. annual rainfall)
Season Tips
199-day frost-free season
Plenty of time for warm-season crops. Start heat-lovers indoors 6–8 weeks before last frost to maximise your harvest window.
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
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Get instant, accurate soil pH readings to fine-tune your amendments.
Boost soil fertility and structure with rich, well-aged organic compost.
🥬 Vegetables to Grow in Benton County
115 vegetables that grow well in Zone 8a with planting dates for Benton County.
Show all 115 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Mar 17 | Apr 21 | Apr 28 | Jul 21 – Aug 25 | 80–100 |
| Amaranth | Feb 24 | Apr 21 | Apr 28 | Jul 28 – Sep 15 | 90–120 |
| Artichoke | — | — | Apr 28 | Sep 1 – Nov 10 | 120–180 |
| Arugula | Mar 10 | Mar 31 | Apr 14 | May 19 – Jul 21 | 30–50 |
| Asparagus | — | — | Apr 28 | — | 730–1095 |
| Beets | — | Mar 31 | — | May 26 – Jun 23 | 50–70 |
| Belgian Endive | Mar 10 | Mar 31 | Apr 14 | Aug 4 – Sep 29 | 110–150 |
| Bitter Melon | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Aug 11 | 60–90 |
| Black Beans | — | Apr 21 | — | Jul 21 – Sep 8 | 90–120 |
| Bok Choy | Mar 10 | Mar 31 | Apr 14 | May 26 – Jun 30 | 40–60 |
| Broccoli | Mar 10 | Mar 31 | Apr 14 | Jun 16 – Jul 28 | 60–90 |
| Broccoli Rabe | Mar 10 | Mar 31 | Apr 14 | May 26 – Jun 30 | 40–60 |
| Brussels Sprouts | Mar 10 | Mar 31 | Apr 14 | Jul 14 – Sep 8 | 90–130 |
| Butternut Squash | Mar 17 | Apr 21 | Apr 28 | Jul 28 – Sep 1 | 85–110 |
| Cabbage | Mar 10 | Mar 31 | Apr 14 | Jun 16 – Aug 11 | 60–100 |
| Calabash | Feb 24 | Apr 21 | Apr 28 | Jul 21 – Sep 15 | 80–120 |
| Cardoon | — | — | Apr 28 | Sep 1 – Oct 13 | 120–150 |
| Carrots | — | Mar 31 | — | Jun 2 – Jul 7 | 60–80 |
| Cauliflower | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Aug 11 | 55–100 |
| Celeriac | Mar 10 | Mar 31 | Apr 14 | Jul 28 – Sep 1 | 100–120 |
| Celery | Mar 10 | Mar 31 | Apr 14 | Jul 7 – Sep 1 | 80–120 |
| Celtuce | Mar 10 | Mar 31 | Apr 14 | Jun 16 – Jul 28 | 60–90 |
| Chard | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Jul 28 | 50–60 |
| Chayote | Feb 24 | Apr 21 | Apr 28 | Sep 1 – Nov 10 | 120–180 |
| Chickpeas | Mar 10 | Mar 31 | Apr 14 | Jul 7 – Aug 18 | 80–110 |
| Chicory | Mar 10 | Mar 31 | Apr 14 | Jun 16 – Jul 28 | 60–85 |
| Chinese Cabbage | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Jul 7 | 50–70 |
| Christmas Lima Beans | Feb 24 | Apr 21 | Apr 28 | Jul 21 – Aug 25 | 80–100 |
| Collard Greens | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Aug 11 | 55–75 |
| Corn | — | Apr 21 | — | Jun 23 – Aug 18 | 60–100 |
| Cowpeas | — | Apr 21 | — | Jun 23 – Aug 4 | 60–90 |
| Cress | Mar 10 | Mar 31 | Apr 14 | Apr 28 – May 19 | 14–21 |
| Crookneck Squash | Mar 17 | Apr 21 | Apr 28 | Jun 16 – Jul 14 | 45–60 |
| Crosne | — | Mar 31 | — | Sep 1 – Nov 3 | 150–200 |
| Cucumber | Mar 17 | Apr 21 | Apr 28 | Jun 23 – Aug 18 | 50–70 |
| Daikon | — | Mar 31 | — | May 26 – Jun 23 | 50–70 |
| Delicata Squash | Mar 17 | Apr 21 | Apr 28 | Jul 21 – Aug 25 | 80–100 |
| Edamame | — | Apr 21 | — | Jul 7 – Aug 18 | 75–100 |
| Eggplant | Feb 10 | Apr 21 | Apr 28 | Jul 7 – Sep 8 | 65–85 |
| Endive | Mar 10 | Mar 31 | Apr 14 | Jun 2 – Jul 7 | 45–65 |
| Escarole | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Jul 7 | 50–70 |
| Fava Beans | Mar 10 | Mar 31 | Apr 14 | Jun 30 – Aug 11 | 75–100 |
| Fennel | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Aug 11 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Ginger | Feb 24 | Apr 21 | Apr 28 | Dec 29 – Jan 12 | 240–300 |
| Green Beans | — | Apr 21 | — | Jun 16 – Aug 11 | 50–65 |
| Horseradish | — | — | Apr 28 | Sep 1 – Nov 10 | 120–180 |
| Hot Peppers | Feb 10 | Apr 21 | Apr 28 | Jul 7 – Oct 13 | 70–120 |
| Hubbard Squash | Mar 17 | Apr 21 | Apr 28 | Aug 11 – Sep 15 | 100–120 |
| Jicama | Feb 24 | Apr 21 | Apr 28 | Sep 1 – Nov 10 | 120–180 |
| Kabocha | Mar 17 | Apr 21 | Apr 28 | Jul 28 – Aug 25 | 85–100 |
| Kai Lan | Mar 10 | Mar 31 | Apr 14 | Jun 2 – Jun 30 | 45–60 |
| Kale | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Aug 4 | 50–70 |
| Kidney Beans | — | Apr 21 | — | Jul 21 – Aug 25 | 85–110 |
| Kohlrabi | Mar 10 | Mar 31 | Apr 14 | Jun 2 – Jul 7 | 45–65 |
| Komatsuna | Mar 10 | Mar 31 | Apr 14 | May 19 – Jun 23 | 35–50 |
| Leeks | Mar 10 | Mar 31 | Apr 14 | Jul 14 – Sep 29 | 90–150 |
| Lentils | Mar 10 | Mar 31 | Apr 14 | Jul 7 – Aug 18 | 80–110 |
| Lettuce | Mar 10 | Mar 31 | Apr 14 | May 19 – Jul 28 | 30–60 |
| Lima Beans | — | Apr 21 | — | Jun 23 – Aug 4 | 60–90 |
| Loofah | Feb 24 | Apr 21 | Apr 28 | Aug 11 – Oct 13 | 100–150 |
| Luffa | Feb 24 | Apr 21 | Apr 28 | Jul 28 – Oct 13 | 90–150 |
| Mache | Mar 10 | Mar 31 | Apr 14 | May 26 – Jun 30 | 40–60 |
| Malabar Spinach | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Jul 21 | 55–70 |
| Melon | Mar 17 | Apr 21 | Apr 28 | Jul 7 – Aug 25 | 70–100 |
| Microgreens | Mar 10 | Mar 31 | Apr 14 | Apr 21 – May 19 | 7–21 |
| Mitsuba | Mar 10 | Mar 31 | Apr 7 | Jun 2 – Jul 28 | 50–70 |
| Mizuna | Mar 10 | Mar 31 | Apr 14 | May 19 – Jun 16 | 30–45 |
| Mustard Greens | Mar 10 | Mar 31 | Apr 14 | May 19 – Jul 21 | 30–50 |
| Napa Cabbage | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Jul 14 | 55–75 |
| New Zealand Spinach | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Jul 21 | 55–70 |
| Okra | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 18 | 50–65 |
| Onion | Mar 10 | Mar 31 | Apr 14 | Jul 14 – Sep 1 | 90–120 |
| Pac Choi | Mar 10 | Mar 31 | Apr 14 | May 26 – Jun 23 | 40–55 |
| Parsnip | — | Mar 31 | — | Jul 14 – Aug 25 | 100–130 |
| Patty Pan Squash | Mar 17 | Apr 21 | Apr 28 | Jun 16 – Jul 14 | 45–60 |
| Peas | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Aug 4 | 55–70 |
| Peppers | Feb 10 | Apr 21 | Apr 28 | Jun 30 – Sep 8 | 60–90 |
| Pole Beans | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 18 | 55–70 |
| Potatoes | Feb 24 | Apr 21 | Apr 28 | Jul 7 – Sep 15 | 70–120 |
| Pumpkin | Mar 17 | Apr 21 | Apr 28 | Jul 28 – Sep 15 | 85–120 |
| Purslane | Mar 10 | Mar 31 | Apr 14 | May 26 – Jun 30 | 40–60 |
| Radicchio | Mar 10 | Mar 31 | Apr 14 | Jun 16 – Jul 21 | 60–80 |
| Radish | — | Mar 31 | — | Apr 28 – May 19 | 22–35 |
| Rhubarb | — | — | May 5 | — | 365–730 |
| Romanesco | Mar 10 | Mar 31 | Apr 14 | Jun 30 – Aug 11 | 75–100 |
| Rutabaga | — | Mar 31 | — | Jun 23 – Jul 28 | 80–100 |
| Salsify | — | Mar 31 | — | Jul 14 – Aug 25 | 100–130 |
| Savoy Cabbage | Mar 10 | Mar 31 | Apr 14 | Jun 23 – Aug 18 | 70–110 |
| Scallions | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Jul 7 | 50–70 |
| Scarlet Runner Beans | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Aug 4 | 60–80 |
| Shallot | Mar 10 | Mar 31 | Apr 14 | Jul 14 – Sep 1 | 90–120 |
| Shiso | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 18 | 50–70 |
| Snap Peas | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 18 | 55–70 |
| Snow Peas | Mar 10 | Mar 31 | Apr 14 | Jun 9 – Aug 4 | 50–65 |
| Soybeans | — | Apr 21 | — | Jul 14 – Sep 8 | 80–120 |
| Spaghetti Squash | Mar 17 | Apr 21 | Apr 28 | Jul 28 – Aug 25 | 85–100 |
| Spinach | Mar 10 | Mar 31 | Apr 14 | May 19 – Jul 21 | 35–50 |
| Squash (Summer) | Mar 17 | Apr 21 | Apr 28 | Jun 16 – Aug 18 | 45–65 |
| Squash (Winter) | Mar 17 | Apr 21 | Apr 28 | Jul 21 – Sep 15 | 80–120 |
| Sunchoke | — | — | Apr 28 | Aug 18 – Oct 13 | 110–150 |
| Sunflower | Feb 24 | Apr 21 | Apr 28 | Jul 7 – Aug 25 | 70–100 |
| Sweet Corn | — | Apr 21 | — | Jun 23 – Aug 4 | 60–90 |
| Sweet Potatoes | Feb 24 | Apr 21 | Apr 28 | Jul 28 – Sep 15 | 90–120 |
| Tatsoi | Mar 10 | Mar 31 | Apr 14 | May 19 – Jun 23 | 35–50 |
| Tomatillo | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Sep 8 | 60–85 |
| Tomatoes | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Sep 8 | 60–85 |
| Turmeric | Feb 24 | Apr 21 | Apr 28 | Dec 29 – Jan 12 | 240–300 |
| Turnip | — | Mar 31 | — | May 12 – Jun 16 | 40–60 |
| Watercress | Mar 10 | Mar 31 | Apr 14 | May 26 – Jun 30 | 40–60 |
| Watermelon | Mar 17 | Apr 21 | Apr 28 | Jul 7 – Aug 25 | 70–100 |
| Wax Beans | — | Apr 21 | — | Jun 16 – Aug 11 | 50–65 |
| Winter Melon | Feb 24 | Apr 21 | Apr 28 | Jul 28 – Sep 15 | 90–120 |
| Yard Long Beans | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 4 | 55–80 |
| Zucchini | Mar 17 | Apr 21 | Apr 28 | Jun 16 – Aug 11 | 45–60 |
🍓 Fruits to Grow in Benton County
27 fruits that grow well in Zone 8a with planting dates for Benton County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | May 5 | Aug 4 – Nov 17 | 90–180 |
| Aronia | — | — | May 5 | — | 730–1095 |
| Blackberries | — | — | May 5 | — | 365–730 |
| Blueberries | — | — | May 5 | — | 730–1095 |
| Boysenberries | — | — | May 5 | — | 365–730 |
| Cantaloupe | — | — | May 5 | Jul 14 – Aug 18 | 70–90 |
| Che Fruit | — | — | May 5 | — | 1095–1825 |
| Elderberries | — | — | May 5 | — | 730–1095 |
| Figs | — | — | May 5 | — | 730–1825 |
| Goji Berries | — | — | May 5 | — | 730–1095 |
| Gooseberries | — | — | May 5 | — | 730–1095 |
| Grapes | — | — | May 5 | — | 730–1095 |
| Ground Cherry | — | — | May 5 | Jul 14 – Sep 8 | 65–80 |
| Hardy Kiwi | — | — | May 5 | — | 1095–1825 |
| Honeydew | — | — | May 5 | Jul 28 – Sep 8 | 80–110 |
| Jostaberry | — | — | May 5 | — | 730–1095 |
| Kiwi | — | — | May 5 | — | 1095–1825 |
| Loquat | — | — | May 5 | — | 730–1825 |
| Medlar | — | — | May 5 | — | 1095–1825 |
| Mulberries | — | — | May 5 | — | 730–1825 |
| Pawpaw | — | — | May 5 | — | 1095–2555 |
| Persimmon | — | — | May 5 | — | 1095–2555 |
| Pomegranate | — | — | May 5 | — | 730–1095 |
| Quince | — | — | May 5 | — | 1095–1825 |
| Raspberries | — | — | May 5 | — | 365–730 |
| Serviceberries | — | — | May 5 | — | 730–1095 |
| Strawberries | — | — | May 5 | Aug 4 – Jan 19 | 90–365 |
🌿 Herbs to Grow in Benton County
42 herbs that grow well in Zone 8a with planting dates for Benton County.
Show all 42 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Mar 10 | Mar 31 | Apr 7 | — | 365–730 |
| Anise | Mar 10 | Mar 31 | Apr 7 | Jul 7 – Sep 22 | 90–120 |
| Basil | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 25 | 50–75 |
| Bee Balm | — | — | Apr 21 | Jul 21 – Oct 6 | 90–120 |
| Borage | Mar 10 | Mar 31 | Apr 7 | Jun 2 – Jul 21 | 50–60 |
| Caraway | Mar 10 | Mar 31 | Apr 7 | — | 365–450 |
| Catnip | — | — | Apr 21 | Jun 23 – Aug 25 | 60–80 |
| Chamomile | Mar 10 | Mar 31 | Apr 7 | Jun 9 – Aug 18 | 60–90 |
| Chervil | Mar 10 | Mar 31 | Apr 7 | May 19 – Jul 21 | 40–60 |
| Chives | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Cilantro | Mar 10 | Mar 31 | Apr 7 | May 19 – Jul 21 | 40–60 |
| Comfrey | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Cumin | Mar 10 | Mar 31 | Apr 7 | Jul 21 – Sep 22 | 100–120 |
| Dill | Mar 10 | Mar 31 | Apr 7 | May 19 – Jul 21 | 40–60 |
| Echinacea | — | — | Apr 21 | Aug 25 – Dec 1 | 120–180 |
| Epazote | Feb 24 | Apr 21 | Apr 28 | Jun 16 – Aug 11 | 45–60 |
| Fennel (herb) | Mar 10 | Mar 31 | Apr 7 | Jun 9 – Aug 18 | 60–90 |
| Feverfew | — | — | Apr 21 | Jul 21 – Oct 6 | 90–120 |
| Garlic Chives | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Horehound | — | — | Apr 21 | Jul 7 – Sep 1 | 75–90 |
| Hyssop | — | — | Apr 21 | Jun 30 – Sep 1 | 70–90 |
| Lavender | — | — | Apr 21 | Jul 21 – Dec 22 | 90–200 |
| Lemon Balm | — | — | Apr 21 | Jun 23 – Aug 11 | 60–70 |
| Lemon Thyme | — | — | Apr 21 | Jun 30 – Sep 1 | 70–90 |
| Lemon Verbena | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Sep 8 | 60–90 |
| Lemongrass | Feb 24 | Apr 21 | Apr 28 | Jul 14 – Oct 13 | 75–120 |
| Lovage | — | — | Apr 21 | Jun 30 – Sep 1 | 70–90 |
| Marjoram | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Mint | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Oregano | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Parsley | Mar 10 | Mar 31 | Apr 7 | Jun 9 – Aug 11 | 60–80 |
| Rosemary | — | — | Apr 21 | Jul 14 – Dec 1 | 80–180 |
| Rue | — | — | Apr 21 | Jun 30 – Sep 1 | 70–90 |
| Sage | — | — | Apr 21 | Jul 7 – Sep 1 | 75–90 |
| Savory | — | — | Apr 21 | Jun 16 – Aug 11 | 50–70 |
| Sorrel | Mar 10 | Mar 31 | Apr 7 | May 19 – Jul 21 | 40–60 |
| Stevia | Feb 24 | Apr 21 | Apr 28 | Jun 30 – Sep 8 | 60–90 |
| Tarragon | — | — | Apr 21 | Jun 23 – Sep 1 | 60–90 |
| Thai Basil | Feb 24 | Apr 21 | Apr 28 | Jun 23 – Aug 25 | 50–75 |
| Thyme | — | — | Apr 21 | Jun 30 – Sep 1 | 70–90 |
| Valerian | — | — | Apr 21 | Aug 25 – Dec 1 | 120–180 |
| Yarrow | — | — | Apr 21 | Jul 21 – Oct 6 | 90–120 |
Monthly Planting Guide for Benton County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Benton County.
Frequently Asked Questions
What planting zone is Benton County, OR?
Benton County is in USDA Hardiness Zone 8a. 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 Benton County, OR?
Based on 31 years of NOAA weather station data, the median last spring frost in Benton County falls around April 14. In 8 out of 10 years, last frost lands between March 4 and May 7 — a 63-day window of variability. Use May 7 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Benton County, OR?
The median first fall frost in Benton County arrives around October 30. In cold years it can arrive as early as October 10; in mild years as late as November 29. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Benton County?
Benton County has a frost-free growing season of approximately 199 days. This is enough time for most warm-season crops including tomatoes, peppers, and squash with proper timing. Climate records show the growing season is trending shorter by about 5.02 days per decade.
What is the soil like in Benton County for gardening?
Benton County has predominantly Silt Loam soil with a pH range of 5.6–6.2 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Benton County?
Benton County has commercial agriculture that includes Wheat, Potatoes, Apples. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Benton County a good location for home gardening?
Benton County scores 55/100 (Moderate) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. Conditions here are moderate — most common crops grow well with standard timing and care.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Benton County gardeners in Zone 8a 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.
