San Juan County, WA — Planting Guide
May in the garden — San Juan County, Washington
Your San Juan County, Washington garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
-
Get basil, peppers, and pole beans seeds going inside
Label every cell. You will absolutely forget which is which otherwise.
-
Bring in the basil, carrots, and cucumber
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Looking ahead to June
- First harvests: basil, carrots, and cucumber
San Juan County is in USDA Zone 9a. The average last spring frost is March 26 and the first fall frost is November 3, giving you a growing season of approximately 222 days.
At an elevation of 371 ft, San Juan County receives approximately 40.9 in of rainfall annually. Summer highs average 82°F with winter lows around 44°F. The predominant soil type is Silt Loam.
Based on 30 years of NOAA climate station data, the last frost date here varies by 53 days year to year — ranging from March 3 in warm years to April 25 in cold years. The growing season is trending longer by about 0.6 days per decade. San Juan County scores 74/100 (Good) on the Microclimate Index.
🌡️ Zone
9a (°F to °F min)
❄️ Last Frost
March 26
🍂 First Frost
November 3
📅 Growing Season
222 days
⛰️ Elevation
371 ft
🌧️ Annual Rainfall
40.9 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 | 5.7 in | 17 days | — | None |
| Feb | 4.7 in | 14 days | — | Low |
| Mar | 4.1 in | 16 days | 0.2 in | Low |
| Apr | 2.6 in | 14 days | 1.7 in | High |
| May | 2.6 in | 9 days | 1.7 in | High |
| Jun | 1.5 in | 6 days | 2.8 in | High |
| Jul | 0.6 in | 2 days | 3.7 in | Critical |
| Aug | 0.8 in | 3 days | 3.5 in | Critical |
| Sep | 1.8 in | 4 days | 2.5 in | High |
| Oct | 3.4 in | 11 days | 0.9 in | Moderate |
| Nov | 6.4 in | 17 days | — | Low |
| Dec | 6.6 in | 19 days | — | None |
Annual total: 40.8 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.
San Juan County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-6.4
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) | Apr 25 | Dec 1 | 220 days |
| Cautious | Apr 6 | Nov 12 | 220 days |
| Average year | Mar 26 | Nov 3 | 222 days |
| Optimistic | Mar 19 | Oct 29 | 224 days |
| Aggressive (risky) | Mar 3 | Oct 17 | 228 days |
Not very — frost dates can vary by ±53 days year-to-year. Use the "Conservative" row in the table below, and keep row covers handy for surprise late frosts.
Slightly — seasons are trending a bit longer (0.6 days/decade). Historical frost dates are still reliable for planning.
Gardening Difficulty Score
San Juan County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in San Juan 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 San Juan County's climate and soil.
County Extension Office
San Juan County Washington State University Extension Extension Office
Phone: 509-335-2811
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 San Juan County
Finding local nurseries & garden centers in San Juan County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to San Juan 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 San Juan County WA" or "garden center San Juan 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 San Juan County WA" or check your extension office and local parks department. Facebook groups like "San Juan County Gardeners" or "Washington 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
15.9 hours
Summer solstice daylight
Shortest Day
8.1 hours
Winter solstice daylight
Peak Sun Hours
10.3 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 | 8.5 hr | 2.1 hr | Short day |
| February | 9.9 hr | 2.9 hr | Short day |
| March | 11.6 hr | 4.1 hr | Short day |
| April | 13.4 hr | 5.5 hr | Neutral |
| May | 15 hr | 7.5 hr | Long day |
| June | 15.9 hr | 8.9 hr | Long day |
| July | 15.5 hr | 10.3 hr | Long day |
| August | 14.1 hr | 9.8 hr | Long day |
| September | 12.3 hr | 7.3 hr | Neutral |
| October | 10.5 hr | 4 hr | Short day |
| November | 8.9 hr | 2.2 hr | Short day |
| December | 8.1 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 | 42°F | 50°F | 🐢 Slow | ~24 weeks |
| Feb | 45°F | 49°F | 🐢 Slow | ~24 weeks |
| Mar | 51°F | 54°F | ♻️ Active | ~14 weeks |
| Apr | 58°F | 61°F | ♻️ Active | ~14 weeks |
| May | 71°F | 68°F | 🔥 Peak | ~8 weeks |
| Jun | 79°F | 76°F | 🔥 Peak | ~8 weeks |
| Jul | 86°F | 81°F | 🔥 Peak | ~8 weeks |
| Aug | 90°F | 85°F | 🔥 Peak | ~8 weeks |
| Sep | 84°F | 81°F | 🔥 Peak | ~8 weeks |
| Oct | 72°F | 75°F | 🔥 Peak | ~8 weeks |
| Nov | 59°F | 65°F | ♻️ Active | ~14 weeks |
| Dec | 48°F | 56°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 San Juan 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 San Juan County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (4 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Apr 1 | Sep 8 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Cowpeas (southern peas) | Mar 30 | Sep 8 | ✓ Yes | Excellent nitrogen fixer for warm climates, edible |
| Sorghum-sudan grass | Apr 1 | Sep 8 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Feb 28 | Sep 1 | ✓ 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 | Apr 11 | Oct 6 | — | 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 24 | Mar 5 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Crimson clover | Aug 31 | Mar 5 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
| Daikon radish | Sep 14 | Mar 12 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Aug 17 | Mar 5 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Sep 29 | Mar 12 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 26 | Mar 12 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jul 27 | Mar 12 | — | Erosion control, weed suppression, good biomass |
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: 9 mph
Fall: 9 mph Winter: 13 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
4.9/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Moderate
Some terrain variation (741 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
20,334 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 2,250 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 40.8 inches of rain per year
- A 1,000 sq ft roof can collect roughly 20,334 gallons annually
- Rainwater harvesting is fully legal in your state
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in San Juan County
Soil Type
Silt Loam
Soil pH 5.4–6.4 · Excessively Drained drainage
Good candidate for raised beds to maximise drainage and extend the season.
Watering Needs
Drought stress: 3.5/10
Low-to-moderate drought stress. Plan to water 1–2 times per week during peak summer. (40.9 in. annual rainfall)
Season Tips
222-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 24-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.
🥬 Vegetables to Grow in San Juan County
115 vegetables that grow well in Zone 9a with planting dates for San Juan County.
Show all 115 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Feb 26 | Mar 26 | Apr 2 | Jun 25 – Jul 30 | 80–100 |
| Amaranth | Feb 12 | Mar 26 | Apr 2 | Jul 2 – Aug 20 | 90–120 |
| Artichoke | — | — | Apr 9 | Aug 13 – Oct 22 | 120–180 |
| Arugula | Feb 26 | Mar 5 | Mar 26 | Apr 30 – Jul 2 | 30–50 |
| Asparagus | — | — | Apr 9 | — | 730–1095 |
| Beets | — | Mar 5 | — | Apr 30 – May 28 | 50–70 |
| Belgian Endive | Feb 26 | Mar 5 | Mar 26 | Jul 16 – Sep 10 | 110–150 |
| Bitter Melon | Feb 12 | Mar 26 | Apr 2 | Jun 4 – Jul 16 | 60–90 |
| Black Beans | — | Apr 2 | — | Jul 2 – Aug 20 | 90–120 |
| Bok Choy | Feb 26 | Mar 5 | Mar 26 | May 7 – Jun 11 | 40–60 |
| Broccoli | Feb 26 | Mar 5 | Mar 26 | May 28 – Jul 9 | 60–90 |
| Broccoli Rabe | Feb 26 | Mar 5 | Mar 26 | May 7 – Jun 11 | 40–60 |
| Brussels Sprouts | Feb 26 | Mar 5 | Mar 26 | Jun 25 – Aug 20 | 90–130 |
| Butternut Squash | Feb 26 | Mar 26 | Apr 2 | Jul 2 – Aug 6 | 85–110 |
| Cabbage | Feb 26 | Mar 5 | Mar 26 | May 28 – Jul 23 | 60–100 |
| Calabash | Feb 12 | Mar 26 | Apr 2 | Jun 25 – Aug 20 | 80–120 |
| Cardoon | — | — | Apr 9 | Aug 13 – Sep 24 | 120–150 |
| Carrots | — | Mar 5 | — | May 7 – Jun 11 | 60–80 |
| Cauliflower | Feb 26 | Mar 5 | Mar 26 | May 21 – Jul 23 | 55–100 |
| Celeriac | Feb 26 | Mar 5 | Mar 26 | Jul 9 – Aug 13 | 100–120 |
| Celery | Feb 26 | Mar 5 | Mar 26 | Jun 18 – Aug 13 | 80–120 |
| Celtuce | Feb 26 | Mar 5 | Mar 26 | May 28 – Jul 9 | 60–90 |
| Chard | Feb 26 | Mar 5 | Mar 26 | May 21 – Jul 9 | 50–60 |
| Chayote | Feb 12 | Mar 26 | Apr 2 | Aug 6 – Oct 15 | 120–180 |
| Chickpeas | Feb 26 | Mar 5 | Mar 26 | Jun 18 – Jul 30 | 80–110 |
| Chicory | Feb 26 | Mar 5 | Mar 26 | May 28 – Jul 9 | 60–85 |
| Chinese Cabbage | Feb 26 | Mar 5 | Mar 26 | May 21 – Jun 18 | 50–70 |
| Christmas Lima Beans | Feb 12 | Mar 26 | Apr 2 | Jun 25 – Jul 30 | 80–100 |
| Collard Greens | Feb 26 | Mar 5 | Mar 26 | May 21 – Jul 23 | 55–75 |
| Corn | — | Apr 2 | — | Jun 4 – Jul 30 | 60–100 |
| Cowpeas | — | Apr 2 | — | Jun 4 – Jul 16 | 60–90 |
| Cress | Feb 26 | Mar 5 | Mar 26 | Apr 9 – Apr 30 | 14–21 |
| Crookneck Squash | Feb 26 | Mar 26 | Apr 2 | May 21 – Jun 18 | 45–60 |
| Crosne | — | Mar 5 | — | Aug 6 – Oct 8 | 150–200 |
| Cucumber | Feb 26 | Mar 26 | Apr 2 | May 28 – Jul 23 | 50–70 |
| Daikon | — | Mar 5 | — | Apr 30 – May 28 | 50–70 |
| Delicata Squash | Feb 26 | Mar 26 | Apr 2 | Jun 25 – Jul 30 | 80–100 |
| Edamame | — | Apr 2 | — | Jun 18 – Jul 30 | 75–100 |
| Eggplant | Feb 12 | Mar 26 | Apr 2 | Jun 11 – Aug 13 | 65–85 |
| Endive | Feb 26 | Mar 5 | Mar 26 | May 14 – Jun 18 | 45–65 |
| Escarole | Feb 26 | Mar 5 | Mar 26 | May 21 – Jun 18 | 50–70 |
| Fava Beans | Feb 26 | Mar 5 | Mar 26 | Jun 11 – Jul 23 | 75–100 |
| Fennel | Feb 12 | Mar 26 | Apr 2 | Jun 4 – Jul 16 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Ginger | Feb 12 | Mar 26 | Apr 2 | Dec 3 – Jan 28 | 240–300 |
| Green Beans | — | Apr 2 | — | May 28 – Jul 23 | 50–65 |
| Horseradish | — | — | Apr 9 | Aug 13 – Oct 22 | 120–180 |
| Hot Peppers | Feb 12 | Mar 26 | Apr 2 | Jun 11 – Sep 17 | 70–120 |
| Hubbard Squash | Feb 26 | Mar 26 | Apr 2 | Jul 16 – Aug 20 | 100–120 |
| Jicama | Feb 12 | Mar 26 | Apr 2 | Aug 6 – Oct 15 | 120–180 |
| Kabocha | Feb 26 | Mar 26 | Apr 2 | Jul 2 – Jul 30 | 85–100 |
| Kai Lan | Feb 26 | Mar 5 | Mar 26 | May 14 – Jun 11 | 45–60 |
| Kale | Feb 26 | Mar 5 | Mar 26 | May 21 – Jul 16 | 50–70 |
| Kidney Beans | — | Apr 2 | — | Jul 2 – Aug 6 | 85–110 |
| Kohlrabi | Feb 26 | Mar 5 | Mar 26 | May 14 – Jun 18 | 45–65 |
| Komatsuna | Feb 26 | Mar 5 | Mar 26 | Apr 30 – Jun 4 | 35–50 |
| Leeks | Feb 26 | Mar 5 | Mar 26 | Jun 25 – Sep 10 | 90–150 |
| Lentils | Feb 26 | Mar 5 | Mar 26 | Jun 18 – Jul 30 | 80–110 |
| Lettuce | Feb 26 | Mar 5 | Mar 26 | Apr 30 – Jul 9 | 30–60 |
| Lima Beans | — | Apr 2 | — | Jun 4 – Jul 16 | 60–90 |
| Loofah | Feb 12 | Mar 26 | Apr 2 | Jul 16 – Sep 17 | 100–150 |
| Luffa | Feb 12 | Mar 26 | Apr 2 | Jul 2 – Sep 17 | 90–150 |
| Mache | Feb 26 | Mar 5 | Mar 26 | May 7 – Jun 11 | 40–60 |
| Malabar Spinach | Feb 12 | Mar 26 | Apr 2 | May 28 – Jun 25 | 55–70 |
| Melon | Feb 26 | Mar 26 | Apr 2 | Jun 11 – Jul 30 | 70–100 |
| Microgreens | Feb 26 | Mar 5 | Mar 26 | Apr 2 – Apr 30 | 7–21 |
| Mitsuba | Feb 26 | Mar 5 | Mar 19 | May 14 – Jul 9 | 50–70 |
| Mizuna | Feb 26 | Mar 5 | Mar 26 | Apr 30 – May 28 | 30–45 |
| Mustard Greens | Feb 26 | Mar 5 | Mar 26 | Apr 30 – Jul 2 | 30–50 |
| Napa Cabbage | Feb 26 | Mar 5 | Mar 26 | May 21 – Jun 25 | 55–75 |
| New Zealand Spinach | Feb 12 | Mar 26 | Apr 2 | May 28 – Jun 25 | 55–70 |
| Okra | Feb 12 | Mar 26 | Apr 2 | May 28 – Jul 23 | 50–65 |
| Onion | Feb 26 | Mar 5 | Mar 26 | Jun 25 – Aug 13 | 90–120 |
| Pac Choi | Feb 26 | Mar 5 | Mar 26 | May 7 – Jun 4 | 40–55 |
| Parsnip | — | Mar 5 | — | Jun 18 – Jul 30 | 100–130 |
| Patty Pan Squash | Feb 26 | Mar 26 | Apr 2 | May 21 – Jun 18 | 45–60 |
| Peas | Feb 26 | Mar 5 | Mar 26 | May 21 – Jul 16 | 55–70 |
| Peppers | Feb 12 | Mar 26 | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Pole Beans | Feb 12 | Mar 26 | Apr 2 | May 28 – Jul 23 | 55–70 |
| Potatoes | Feb 12 | Mar 26 | Apr 2 | Jun 11 – Aug 20 | 70–120 |
| Pumpkin | Feb 26 | Mar 26 | Apr 2 | Jul 2 – Aug 20 | 85–120 |
| Purslane | Feb 26 | Mar 5 | Mar 26 | May 7 – Jun 11 | 40–60 |
| Radicchio | Feb 26 | Mar 5 | Mar 26 | May 28 – Jul 2 | 60–80 |
| Radish | — | Mar 5 | — | Apr 2 – Apr 23 | 22–35 |
| Romanesco | Feb 26 | Mar 5 | Mar 26 | Jun 11 – Jul 23 | 75–100 |
| Rutabaga | — | Mar 5 | — | May 28 – Jul 2 | 80–100 |
| Salsify | — | Mar 5 | — | Jun 18 – Jul 30 | 100–130 |
| Savoy Cabbage | Feb 26 | Mar 5 | Mar 26 | Jun 4 – Jul 30 | 70–110 |
| Scallions | Feb 26 | Mar 5 | Mar 26 | May 21 – Jun 18 | 50–70 |
| Scarlet Runner Beans | Feb 12 | Mar 26 | Apr 2 | Jun 4 – Jul 9 | 60–80 |
| Shallot | Feb 26 | Mar 5 | Mar 26 | Jun 25 – Aug 13 | 90–120 |
| Shiso | Feb 12 | Apr 2 | Apr 2 | May 28 – Jul 23 | 50–70 |
| Snap Peas | Feb 12 | Mar 26 | Apr 2 | May 28 – Jul 23 | 55–70 |
| Snow Peas | Feb 26 | Mar 5 | Mar 26 | May 21 – Jul 16 | 50–65 |
| Soybeans | — | Apr 2 | — | Jun 25 – Aug 20 | 80–120 |
| Spaghetti Squash | Feb 26 | Mar 26 | Apr 2 | Jul 2 – Jul 30 | 85–100 |
| Spinach | Feb 26 | Mar 5 | Mar 26 | Apr 30 – Jul 2 | 35–50 |
| Squash (Summer) | Feb 26 | Mar 26 | Apr 2 | May 21 – Jul 23 | 45–65 |
| Squash (Winter) | Feb 26 | Mar 26 | Apr 2 | Jun 25 – Aug 20 | 80–120 |
| Sunchoke | — | — | Apr 9 | Jul 30 – Sep 24 | 110–150 |
| Sunflower | Feb 12 | Mar 26 | Apr 2 | Jun 11 – Jul 30 | 70–100 |
| Sweet Corn | — | Apr 2 | — | Jun 4 – Jul 16 | 60–90 |
| Sweet Potatoes | Feb 12 | Mar 26 | Apr 2 | Jul 2 – Aug 20 | 90–120 |
| Tatsoi | Feb 26 | Mar 5 | Mar 26 | Apr 30 – Jun 4 | 35–50 |
| Tomatillo | Feb 12 | Mar 26 | Apr 2 | Jun 4 – Aug 13 | 60–85 |
| Tomatoes | Feb 12 | Mar 26 | Apr 2 | Jun 4 – Aug 13 | 60–85 |
| Turmeric | Feb 12 | Mar 26 | Apr 2 | Dec 3 – Jan 28 | 240–300 |
| Turnip | — | Mar 5 | — | Apr 16 – May 21 | 40–60 |
| Watercress | Feb 26 | Mar 5 | Mar 26 | May 7 – Jun 11 | 40–60 |
| Watermelon | Feb 26 | Mar 26 | Apr 2 | Jun 11 – Jul 30 | 70–100 |
| Wax Beans | — | Apr 2 | — | May 28 – Jul 23 | 50–65 |
| Winter Melon | Feb 12 | Mar 26 | Apr 2 | Jul 2 – Aug 20 | 90–120 |
| Yam | Feb 12 | Mar 26 | Apr 2 | Oct 1 – Jan 28 | 180–330 |
| Yard Long Beans | Feb 12 | Mar 26 | Apr 2 | May 28 – Jul 9 | 55–80 |
| Zucchini | Feb 26 | Mar 26 | Apr 2 | May 21 – Jul 16 | 45–60 |
🍓 Fruits to Grow in San Juan County
24 fruits that grow well in Zone 9a with planting dates for San Juan County.
Show all 24 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Apr 9 | Jul 9 – Oct 22 | 90–180 |
| Blackberries | — | — | Apr 9 | — | 365–730 |
| Boysenberries | — | — | Apr 9 | — | 365–730 |
| Cantaloupe | — | — | Apr 9 | Jun 18 – Jul 23 | 70–90 |
| Che Fruit | — | — | Apr 9 | — | 1095–1825 |
| Dragon Fruit | — | — | Apr 9 | — | 365–730 |
| Elderberries | — | — | Apr 9 | — | 730–1095 |
| Figs | — | — | Apr 9 | — | 730–1825 |
| Goji Berries | — | — | Apr 9 | — | 730–1095 |
| Grapes | — | — | Apr 9 | — | 730–1095 |
| Ground Cherry | — | — | Apr 9 | Jun 18 – Aug 13 | 65–80 |
| Guava | — | — | Apr 9 | — | 365–730 |
| Honeydew | — | — | Apr 9 | Jul 2 – Aug 13 | 80–110 |
| Kiwi | — | — | Apr 9 | — | 1095–1825 |
| Loquat | — | — | Apr 9 | — | 730–1825 |
| Mulberries | — | — | Apr 9 | — | 730–1825 |
| Passion Fruit | — | — | Apr 9 | — | 365–545 |
| Pawpaw | — | — | Apr 9 | — | 1095–2555 |
| Persimmon | — | — | Apr 9 | — | 1095–2555 |
| Pomegranate | — | — | Apr 9 | — | 730–1095 |
| Quince | — | — | Apr 9 | — | 1095–1825 |
| Raspberries | — | — | Apr 9 | — | 365–730 |
| Serviceberries | — | — | Apr 9 | — | 730–1095 |
| Strawberries | — | — | Apr 9 | Jul 9 – Feb 4 | 90–365 |
🌿 Herbs to Grow in San Juan County
40 herbs that grow well in Zone 9a with planting dates for San Juan County.
Show all 40 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Anise | Feb 26 | Mar 5 | Mar 19 | Jun 18 – Sep 3 | 90–120 |
| Basil | Feb 12 | Apr 2 | Apr 2 | May 28 – Jul 30 | 50–75 |
| Bee Balm | — | — | Apr 2 | Jul 2 – Sep 17 | 90–120 |
| Borage | Feb 26 | Mar 5 | Mar 19 | May 14 – Jul 2 | 50–60 |
| Caraway | Feb 26 | Mar 5 | Mar 19 | — | 365–450 |
| Catnip | — | — | Apr 2 | Jun 4 – Aug 6 | 60–80 |
| Chamomile | Feb 26 | Mar 5 | Mar 19 | May 21 – Jul 30 | 60–90 |
| Chervil | Feb 26 | Mar 5 | Mar 19 | Apr 30 – Jul 2 | 40–60 |
| Chives | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Cilantro | Feb 26 | Mar 5 | Mar 19 | Apr 30 – Jul 2 | 40–60 |
| Comfrey | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Cumin | Feb 26 | Mar 5 | Mar 19 | Jul 2 – Sep 3 | 100–120 |
| Dill | Feb 26 | Mar 5 | Mar 19 | Apr 30 – Jul 2 | 40–60 |
| Echinacea | — | — | Apr 2 | Aug 6 – Nov 12 | 120–180 |
| Epazote | Feb 12 | Apr 2 | Apr 2 | May 21 – Jul 16 | 45–60 |
| Fennel (herb) | Feb 26 | Mar 5 | Mar 19 | May 21 – Jul 30 | 60–90 |
| Feverfew | — | — | Apr 2 | Jul 2 – Sep 17 | 90–120 |
| Garlic Chives | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Horehound | — | — | Apr 2 | Jun 18 – Aug 13 | 75–90 |
| Hyssop | — | — | Apr 2 | Jun 11 – Aug 13 | 70–90 |
| Lavender | — | — | Apr 2 | Jul 2 – Dec 3 | 90–200 |
| Lemon Balm | — | — | Apr 2 | Jun 4 – Jul 23 | 60–70 |
| Lemon Thyme | — | — | Apr 2 | Jun 11 – Aug 13 | 70–90 |
| Lemon Verbena | Feb 12 | Apr 2 | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Lemongrass | Feb 12 | Apr 2 | Apr 2 | Jun 18 – Sep 17 | 75–120 |
| Marjoram | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Mint | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Oregano | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Parsley | Feb 26 | Mar 5 | Mar 19 | May 21 – Jul 23 | 60–80 |
| Rosemary | — | — | Apr 2 | Jun 25 – Nov 12 | 80–180 |
| Rue | — | — | Apr 2 | Jun 11 – Aug 13 | 70–90 |
| Sage | — | — | Apr 2 | Jun 18 – Aug 13 | 75–90 |
| Savory | — | — | Apr 2 | May 28 – Jul 23 | 50–70 |
| Sorrel | Feb 26 | Mar 5 | Mar 19 | Apr 30 – Jul 2 | 40–60 |
| Stevia | Feb 12 | Apr 2 | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Tarragon | — | — | Apr 2 | Jun 4 – Aug 13 | 60–90 |
| Thai Basil | Feb 12 | Apr 2 | Apr 2 | May 28 – Jul 30 | 50–75 |
| Thyme | — | — | Apr 2 | Jun 11 – Aug 13 | 70–90 |
| Valerian | — | — | Apr 2 | Aug 6 – Nov 12 | 120–180 |
| Yarrow | — | — | Apr 2 | Jul 2 – Sep 17 | 90–120 |
Monthly Planting Guide for San Juan County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in San Juan County.
Frequently Asked Questions
What planting zone is San Juan County, WA?
San Juan 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 San Juan County, WA?
Based on 30 years of NOAA weather station data, the median last spring frost in San Juan County falls around March 26. In 8 out of 10 years, last frost lands between March 3 and April 25 — a 53-day window of variability. Use April 25 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in San Juan County, WA?
The median first fall frost in San Juan County arrives around November 3. In cold years it can arrive as early as October 17; in mild years as late as December 1. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in San Juan County?
San Juan County has a frost-free growing season of approximately 222 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 0.6 days per decade.
What is the soil like in San Juan County for gardening?
San Juan County has predominantly Silt Loam soil with a pH range of 5.4–6.4 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in San Juan County?
San Juan County has commercial agriculture that includes Wheat, Hay, Apples, Cattle, Potatoes. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is San Juan County a good location for home gardening?
San Juan County scores 74/100 (Good) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. This is an above-average location for home gardening with relatively predictable growing conditions.
Your San Juan County Garden Planner — Free
A 24-page printable planner built for San Juan 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