Clatsop County, OR — Planting Guide
Clatsop County is in USDA Zone 9a. The average last spring frost is April 12 and the first fall frost is November 4, giving you a growing season of approximately 206 days.
At an elevation of 412 ft, Clatsop County receives approximately 54.1 in of rainfall annually. Summer highs average 86°F with winter lows around 47°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 44 days year to year — ranging from March 17 in warm years to April 30 in cold years. The growing season is trending longer by about 1.93 days per decade. Clatsop County scores 62/100 (Good) on the Microclimate Index.
🌡️ Zone
9a (20°F to 25°F min)
❄️ Last Frost
April 12
🍂 First Frost
November 4
📅 Growing Season
206 days
⛰️ Elevation
412 ft
🌧️ Annual Rainfall
54.1 in
Monthly Watering Calendar for Clatsop County
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
The practical takeaway: In humid climates, watering is usually about timing (morning, not evening, to prevent disease) more than volume. In dry climates, it's about depth (water deep, less often) more than frequency. Clatsop County's 54" annual tells you which side you're on.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 8.4 in | 19 days | — | None |
| Feb | 5.2 in | 14 days | — | Low |
| Mar | 4.8 in | 17 days | — | Low |
| Apr | 3.8 in | 11 days | 0.5 in | Low |
| May | 3.6 in | 10 days | 0.7 in | Moderate |
| Jun | 2.1 in | 6 days | 2.2 in | High |
| Jul | 0.9 in | 3 days | 3.4 in | Critical |
| Aug | 1.1 in | 2 days | 3.2 in | Critical |
| Sep | 2.4 in | 5 days | 1.9 in | High |
| Oct | 4.2 in | 12 days | 0.1 in | Low |
| Nov | 8.4 in | 18 days | — | Low |
| Dec | 9.3 in | 20 days | — | None |
Annual total: 54.2 in. Water needs vary by crop — tomatoes need ~1.2"/week while herbs like rosemary need only 0.3"/week. Check individual plant pages for crop-specific water budgets that factor in your county's rainfall and soil drainage.
Clatsop County Soil Profile
Soil Type
Silt Loam
Soil pH
5.6-6.7
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) | Apr 30 | Nov 30 | 214 days |
| Cautious | Apr 18 | Nov 13 | 209 days |
| Average year | Apr 12 | Nov 4 | 206 days |
| Optimistic | Apr 1 | Oct 28 | 210 days |
| Aggressive (risky) | Mar 17 | Oct 13 | 210 days |
Not very — frost dates can vary by ±44 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 longer here (about 1.9 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Clatsop County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in Clatsop 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 Clatsop County's climate and soil.
County Extension Office
Clatsop 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 Clatsop County
Finding local nurseries & garden centers in Clatsop County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Clatsop 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 Clatsop County OR" or "garden center Clatsop 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 Clatsop County OR" or check your extension office and local parks department. Facebook groups like "Clatsop 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 in Clatsop County
Monthly daylight hours and peak sun — critical for onion varieties, photoperiod-sensitive plants, and solar garden planning.
Quick context: Onions are a great example of why day length matters. They "bulb up" only when daylight hits a specific number of hours — plant the wrong variety (short-day in the north, long-day in the south) and you'll get tiny bulbs no matter how well you grow them. Clatsop County's latitude determines which onion varieties succeed.
Longest Day
15.5 hours
Summer solstice daylight
Shortest Day
8.5 hours
Winter solstice daylight
Peak Sun Hours
10.5 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 | 8.8 hr | 2.2 hr | Short day |
| February | 10.1 hr | 3.1 hr | Short day |
| March | 11.6 hr | 3.9 hr | Short day |
| April | 13.3 hr | 5.6 hr | Neutral |
| May | 14.8 hr | 7.1 hr | Long day |
| June | 15.5 hr | 8.9 hr | Long day |
| July | 15.2 hr | 10.5 hr | Long day |
| August | 14 hr | 9.2 hr | Long day |
| September | 12.3 hr | 7.5 hr | Neutral |
| October | 10.7 hr | 4.1 hr | Short day |
| November | 9.2 hr | 2.3 hr | Short day |
| December | 8.5 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 in Clatsop County
Monthly soil temps tell you when to plant warm-season crops, and when your compost pile is actively working.
Quick context: Mulched soil swings less. The mulch insulates against both winter cold and summer heat. In Clatsop County, an aggressive mulch program shifts your effective soil temperature curve toward optimal for most crops.
Plant Warm Crops When
Soil reaches 60°F+
Soil warm enough from Apr through Oct.
Best Month to Compost
May
Microbial activity peaks when soil is warm.
Active Composting
8 months
Nearly year-round composting.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 44°F | 51°F | 🐢 Slow | ~24 weeks |
| Feb | 43°F | 49°F | 🐢 Slow | ~24 weeks |
| Mar | 49°F | 55°F | 🐢 Slow | ~24 weeks |
| Apr | 60°F | 60°F | ♻️ Active | ~14 weeks |
| May | 73°F | 69°F | 🔥 Peak | ~8 weeks |
| Jun | 80°F | 76°F | 🔥 Peak | ~8 weeks |
| Jul | 90°F | 84°F | 🔥 Peak | ~8 weeks |
| Aug | 91°F | 85°F | 🔥 Peak | ~8 weeks |
| Sep | 85°F | 83°F | 🔥 Peak | ~8 weeks |
| Oct | 71°F | 76°F | 🔥 Peak | ~8 weeks |
| Nov | 60°F | 66°F | ♻️ Active | ~14 weeks |
| Dec | 50°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 Clatsop County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
The practical takeaway: Pest score isn't pass/fail. It's a planning input. Higher scores mean: more compost (resilient plants), wider spacing (air circulation), resistant varieties (built-in defense), and inspection (catch issues at egg stage).
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 | Low | 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 Clatsop County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with planting dates calibrated for your area.
For new gardeners: Cover crops protect microbial life through winter and summer. Bare soil bakes; covered soil stays cooler, moister, and biologically active. The difference shows up in next year's crops.
Spring Cover Crops (4 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Apr 15 | Aug 26 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Cowpeas (southern peas) | Apr 20 | Sep 2 | ✓ Yes | Excellent nitrogen fixer for warm climates, edible |
| Sorghum-sudan grass | Apr 23 | Aug 26 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Mar 16 | Sep 9 | ✓ 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 13 | Oct 21 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (7 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Austrian winter peas | Aug 30 | Mar 22 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Crimson clover | Sep 11 | Mar 29 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
| Daikon radish | Sep 13 | Mar 22 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Aug 23 | Mar 29 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Oct 9 | Mar 22 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Aug 9 | Mar 22 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jul 28 | Mar 29 | — | Erosion control, weed suppression, good biomass |
Wind & Microclimate in Clatsop County
The practical takeaway: Why care about wind? Above about 10 mph, evaporation jumps and pollinators struggle to land on flowers. Clatsop County's 9.6 mph average means you can plant tall crops without much support, but it doesn't mean ignore wind — a 20+ mph storm still snaps unstaked tomatoes.
Wind dries soil, stresses plants, and affects frost patterns. Understanding your exposure helps with garden placement.
Seasonal Wind Speed
Spring: 13 mph Summer: 10 mph
Fall: 8 mph Winter: 13 mph
Prevailing wind: SW. 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 (918 ft range). Garden on slopes or higher ground if possible to avoid late-season frost pockets.
Rainwater Harvesting in Clatsop County
How much water you can collect, when to collect it, and what size system you need for your garden.
Why it matters: Rainwater scales linearly with roof area. A 2,000 sq ft roof in Clatsop County captures ~1,200 gallons per 1" of rain — given 54" annual rainfall, that's thousands of gallons a year if you have storage to hold it.
Annual Collection
27,013 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 1,000 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
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 54.2 inches of rain per year
- A 1,000 sq ft roof can collect roughly 27,013 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 Clatsop County
Soil Type
Silt Loam
Soil pH 5.6–6.7 · Well Drained drainage
Native soil is well-suited to most vegetables and herbs with regular compost additions.
Watering Needs
Drought stress: 1.5/10
Clatsop County has very low drought pressure. Natural rainfall usually meets garden needs — water only during extended dry spells.
Season Tips
206-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.
Your Free Printable Garden Planner
Plan every bed, every planting, every harvest — in one place. This 22-page printable includes your zone's planting calendar, a month-by-month task list, a seed inventory tracker, a harvest log, and succession-planting charts. Built to print, write in, and actually use all season.
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.
Monthly Planting Guide for Clatsop County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Clatsop County.
Frequently Asked Questions
What planting zone is Clatsop County, OR?
Clatsop County is in USDA Hardiness Zone 9a. 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 Clatsop County, OR?
Based on 31 years of NOAA weather station data, the median last spring frost in Clatsop County falls around April 12. In 8 out of 10 years, last frost lands between March 17 and April 30 — a 44-day window of variability. Use April 30 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Clatsop County, OR?
The median first fall frost in Clatsop County arrives around November 4. In cold years it can arrive as early as October 13; in mild years as late as November 30. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Clatsop County?
Clatsop County has a frost-free growing season of approximately 206 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 longer by about 1.93 days per decade.
What is the soil like in Clatsop County for gardening?
Clatsop County has predominantly Silt Loam soil with a pH range of 5.6–6.7 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Clatsop County?
Clatsop County has commercial agriculture that includes Wheat, Apples, Potatoes, Hops. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Clatsop County a good location for home gardening?
Clatsop County scores 62/100 (Good) 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.
Your Clatsop County Garden Planner — Free
A 22-page printable planner built for Clatsop County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
Seed Saving & Storage Guide
Most saved seeds go bad before next season. This shows exactly when to pick, how to dry, and where to store seeds from 200 plants so yours don't.
- 200 plants, step-by-step: life cycle, pollination type, isolation
- Exact temperature + humidity ranges that keep seeds viable
- Bonus: searchable Google Sheets tracker + custom GPT assistant
Composting Guide for Homesteaders
Turn kitchen scraps and yard waste into compost that actually feeds the garden — instead of a pile that smells, attracts pests, and never breaks down.
- 14 sections on composting methods, soil science, and troubleshooting
- The 7-step hot-compost system from start to finish
- Bonus tools: troubleshooting chart, safety guide, monitoring log