Union County, OR — Planting Guide
Union County is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is September 26, giving you a growing season of approximately 137 days.
At an elevation of 2,751 ft, Union County receives approximately 23.5 in of rainfall annually. Summer highs average 86°F with winter lows around 18°F. The predominant soil type is Silt Loam.
Based on 29 years of NOAA climate station data, the last frost date here varies by 45 days year to year — ranging from April 24 in warm years to June 8 in cold years. The growing season is trending longer by about 2.18 days per decade. Union County scores 53/100 (Moderate) on the Microclimate Index.
🌡️ Zone
5b (-15°F to -10°F min)
❄️ Last Frost
May 12
🍂 First Frost
September 26
📅 Growing Season
137 days
⛰️ Elevation
2,751 ft
🌧️ Annual Rainfall
23.5 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 | 2.9 in | 18 days | — | None |
| Feb | 2.6 in | 16 days | — | None |
| Mar | 2.3 in | 16 days | — | None |
| Apr | 1.5 in | 13 days | 2.8 in | High |
| May | 1.5 in | 9 days | 2.8 in | High |
| Jun | 0.9 in | 7 days | 3.4 in | Critical |
| Jul | 0.4 in | 2 days | 3.9 in | Critical |
| Aug | 0.5 in | 3 days | 3.8 in | Critical |
| Sep | 1 in | 5 days | 3.3 in | Critical |
| Oct | 2 in | 11 days | 2.3 in | High |
| Nov | 3.8 in | 15 days | — | None |
| Dec | 4.2 in | 19 days | — | None |
Annual total: 23.6 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.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.6
Drainage
Well Drained
Frost Risk Probability
Based on 29 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) | Jun 8 | Oct 19 | 133 days |
| Cautious | May 18 | Oct 4 | 139 days |
| Average year | May 12 | Sep 26 | 137 days |
| Optimistic | May 3 | Sep 14 | 134 days |
| Aggressive (risky) | Apr 24 | Sep 2 | 131 days |
Not very — frost dates can vary by ±45 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 2.2 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Union County presents some gardening challenges. Choose adapted varieties and plan around frost dates.
Local Gardening Help in Union 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 Union County's climate and soil.
County Extension Office
Union 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 Union County
Finding local nurseries & garden centers in Union County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Union 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 Union County OR" or "garden center Union 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 Union County OR" or check your extension office and local parks department. Facebook groups like "Union 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
15.4 hours
Summer solstice daylight
Shortest Day
8.6 hours
Winter solstice daylight
Peak Sun Hours
10.1 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 | 8.9 hr | 2.1 hr | Short day |
| February | 10.2 hr | 3.1 hr | Short day |
| March | 11.6 hr | 4.1 hr | Short day |
| April | 13.3 hr | 5.8 hr | Neutral |
| May | 14.7 hr | 7.3 hr | Long day |
| June | 15.4 hr | 8.6 hr | Long day |
| July | 15.1 hr | 10.1 hr | Long day |
| August | 13.9 hr | 9.6 hr | Neutral |
| September | 12.3 hr | 7.4 hr | Neutral |
| October | 10.7 hr | 4 hr | Short day |
| November | 9.3 hr | 2.3 hr | Short day |
| December | 8.6 hr | 2 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 Jun through Sep.
Best Month to Compost
Jul
Microbial activity peaks when soil is warm.
Active Composting
6 months
Solid season. Piles go dormant in winter.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | 14°F | 25°F | ❄️ Dormant | ~36 weeks |
| Feb | 17°F | 25°F | ❄️ Dormant | ~36 weeks |
| Mar | 25°F | 29°F | ❄️ Dormant | ~36 weeks |
| Apr | 37°F | 38°F | ❄️ Dormant | ~36 weeks |
| May | 53°F | 48°F | ♻️ Active | ~14 weeks |
| Jun | 62°F | 58°F | ♻️ Active | ~14 weeks |
| Jul | 70°F | 63°F | 🔥 Peak | ~8 weeks |
| Aug | 72°F | 68°F | 🔥 Peak | ~8 weeks |
| Sep | 65°F | 63°F | ♻️ Active | ~14 weeks |
| Oct | 51°F | 54°F | ♻️ Active | ~14 weeks |
| Nov | 37°F | 42°F | ❄️ Dormant | ~36 weeks |
| Dec | 25°F | 33°F | ❄️ Dormant | ~36 weeks |
Highlighted rows = soil 60°F+ (safe for warm-season transplants). Compost finishes fastest during peak activity months.
Pest & Disease Pressure in Union County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
Insect Pest Pressure
Moderate — common pests appear but manageable with monitoring.
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 | Moderate | May, Jun, Jul, Aug |
| Japanese beetles | Moderate | Jun, Jul, Aug |
| Squash bugs | Low | Jun, Jul, Aug |
| Tomato hornworms | Moderate | Jul, Aug |
| Cabbage loopers | Low | May, Jun, Jul, Aug |
| Slugs | Low | Apr, May, Jun |
Organic pest management tips
- Maintain healthy soil with regular compost additions to build natural pest resistance
- Practice crop rotation annually to break pest cycles
- Encourage beneficial insects with flowering herbs like dill, fennel, and yarrow
Cover Crops for Union County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (3 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | May 19 | Jul 18 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Sorghum-sudan grass | May 14 | Jul 18 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Apr 15 | Jul 18 | ✓ 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 25 | Aug 29 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (6 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Austrian winter peas | Jul 27 | Apr 28 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Daikon radish | Aug 18 | Apr 21 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jul 12 | Apr 28 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 12 | Apr 28 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 1 | Apr 21 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 18 | Apr 21 | — | 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: 9 mph Summer: 8 mph
Fall: 9 mph Winter: 12 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 (710 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
11,762 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
7 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
Jun, 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 23.6 inches of rain per year
- A 1,000 sq ft roof can collect roughly 11,762 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Jun, Jul, Aug)
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in Union County
Soil Type
Silt Loam
Soil pH 5.2–6.6 · 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. (23.5 in. annual rainfall)
Season Tips
137-day frost-free season
Start warm-season crops indoors and focus on short-season varieties. Cold frames extend your season by 3–4 weeks in fall.
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 Union County
106 vegetables that grow well in Zone 5b with planting dates for Union County.
Show all 106 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 7 | May 19 | May 26 | Aug 18 – Sep 22 | 80–100 |
| Amaranth | Mar 17 | May 19 | May 26 | Aug 25 – Oct 13 | 90–120 |
| Arugula | Apr 7 | Apr 28 | May 12 | Jun 16 – Aug 18 | 30–50 |
| Asparagus | — | — | May 26 | — | 730–1095 |
| Beets | — | Apr 28 | — | Jun 23 – Jul 21 | 50–70 |
| Belgian Endive | Apr 7 | Apr 28 | May 12 | Sep 1 – Oct 27 | 110–150 |
| Bitter Melon | Mar 17 | May 19 | May 26 | Jul 28 – Sep 8 | 60–90 |
| Black Beans | — | May 19 | — | Aug 18 – Oct 6 | 90–120 |
| Bok Choy | Apr 7 | Apr 28 | May 12 | Jun 23 – Jul 28 | 40–60 |
| Broccoli | Apr 7 | Apr 28 | May 12 | Jul 14 – Aug 25 | 60–90 |
| Broccoli Rabe | Apr 7 | Apr 28 | May 12 | Jun 23 – Jul 28 | 40–60 |
| Brussels Sprouts | Apr 7 | Apr 28 | May 12 | Aug 11 – Oct 6 | 90–130 |
| Butternut Squash | Apr 7 | May 19 | May 26 | Aug 25 – Sep 29 | 85–110 |
| Cabbage | Apr 7 | Apr 28 | May 12 | Jul 14 – Sep 8 | 60–100 |
| Calabash | Mar 17 | May 19 | May 26 | Aug 18 – Oct 13 | 80–120 |
| Carrots | — | Apr 28 | — | Jun 30 – Aug 4 | 60–80 |
| Cauliflower | Apr 7 | Apr 28 | May 12 | Jul 7 – Sep 8 | 55–100 |
| Celeriac | Apr 7 | Apr 28 | May 12 | Aug 25 – Sep 29 | 100–120 |
| Celery | Apr 7 | Apr 28 | May 12 | Aug 4 – Sep 29 | 80–120 |
| Celtuce | Apr 7 | Apr 28 | May 12 | Jul 14 – Aug 25 | 60–90 |
| Chard | Apr 7 | Apr 28 | May 12 | Jul 7 – Aug 25 | 50–60 |
| Chickpeas | Apr 7 | Apr 28 | May 12 | Aug 4 – Sep 15 | 80–110 |
| Chicory | Apr 7 | Apr 28 | May 12 | Jul 14 – Aug 25 | 60–85 |
| Chinese Cabbage | Apr 7 | Apr 28 | May 12 | Jul 7 – Aug 4 | 50–70 |
| Christmas Lima Beans | Mar 17 | May 19 | May 26 | Aug 18 – Sep 22 | 80–100 |
| Collard Greens | Apr 7 | Apr 28 | May 12 | Jul 7 – Sep 8 | 55–75 |
| Corn | — | May 19 | — | Jul 21 – Sep 15 | 60–100 |
| Cowpeas | — | May 19 | — | Jul 21 – Sep 1 | 60–90 |
| Cress | Apr 7 | Apr 28 | May 12 | May 26 – Jun 16 | 14–21 |
| Crookneck Squash | Apr 7 | May 19 | May 26 | Jul 14 – Aug 11 | 45–60 |
| Crosne | — | Apr 28 | — | Sep 29 – Oct 13 | 150–200 |
| Cucumber | Apr 7 | May 19 | May 26 | Jul 21 – Sep 15 | 50–70 |
| Daikon | — | Apr 28 | — | Jun 23 – Jul 21 | 50–70 |
| Delicata Squash | Apr 7 | May 19 | May 26 | Aug 18 – Sep 22 | 80–100 |
| Edamame | — | May 19 | — | Aug 4 – Sep 15 | 75–100 |
| Eggplant | Mar 3 | May 19 | May 26 | Aug 4 – Oct 6 | 65–85 |
| Endive | Apr 7 | Apr 28 | May 12 | Jun 30 – Aug 4 | 45–65 |
| Escarole | Apr 7 | Apr 28 | May 12 | Jul 7 – Aug 4 | 50–70 |
| Fava Beans | Apr 7 | Apr 28 | May 12 | Jul 28 – Sep 8 | 75–100 |
| Fennel | Mar 17 | May 19 | May 26 | Jul 28 – Sep 8 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | May 19 | — | Jul 14 – Sep 8 | 50–65 |
| Horseradish | — | — | May 26 | Sep 29 – Nov 10 | 120–180 |
| Hot Peppers | Mar 3 | May 19 | May 26 | Aug 4 – Nov 10 | 70–120 |
| Hubbard Squash | Apr 7 | May 19 | May 26 | Sep 8 – Oct 13 | 100–120 |
| Kabocha | Apr 7 | May 19 | May 26 | Aug 25 – Sep 22 | 85–100 |
| Kai Lan | Apr 7 | Apr 28 | May 12 | Jun 30 – Jul 28 | 45–60 |
| Kale | Apr 7 | Apr 28 | May 12 | Jul 7 – Sep 1 | 50–70 |
| Kidney Beans | — | May 19 | — | Aug 18 – Sep 22 | 85–110 |
| Kohlrabi | Apr 7 | Apr 28 | May 12 | Jun 30 – Aug 4 | 45–65 |
| Komatsuna | Apr 7 | Apr 28 | May 12 | Jun 16 – Jul 21 | 35–50 |
| Leeks | Apr 7 | Apr 28 | May 12 | Aug 11 – Oct 27 | 90–150 |
| Lentils | Apr 7 | Apr 28 | May 12 | Aug 4 – Sep 15 | 80–110 |
| Lettuce | Apr 7 | Apr 28 | May 12 | Jun 16 – Aug 25 | 30–60 |
| Lima Beans | — | May 19 | — | Jul 21 – Sep 1 | 60–90 |
| Mache | Apr 7 | Apr 28 | May 12 | Jun 23 – Jul 28 | 40–60 |
| Melon | Apr 7 | May 19 | May 26 | Aug 4 – Sep 22 | 70–100 |
| Microgreens | Apr 7 | Apr 28 | May 12 | May 19 – Jun 16 | 7–21 |
| Mitsuba | Apr 7 | Apr 28 | May 5 | Jun 30 – Aug 25 | 50–70 |
| Mizuna | Apr 7 | Apr 28 | May 12 | Jun 16 – Jul 14 | 30–45 |
| Mustard Greens | Apr 7 | Apr 28 | May 12 | Jun 16 – Aug 18 | 30–50 |
| Napa Cabbage | Apr 7 | Apr 28 | May 12 | Jul 7 – Aug 11 | 55–75 |
| New Zealand Spinach | Mar 17 | May 19 | May 26 | Jul 21 – Aug 18 | 55–70 |
| Okra | Mar 17 | May 19 | May 26 | Jul 21 – Sep 15 | 50–65 |
| Onion | Apr 7 | Apr 28 | May 12 | Aug 11 – Sep 29 | 90–120 |
| Pac Choi | Apr 7 | Apr 28 | May 12 | Jun 23 – Jul 21 | 40–55 |
| Parsnip | — | Apr 28 | — | Aug 11 – Sep 22 | 100–130 |
| Patty Pan Squash | Apr 7 | May 19 | May 26 | Jul 14 – Aug 11 | 45–60 |
| Peas | Apr 7 | Apr 28 | May 12 | Jul 7 – Sep 1 | 55–70 |
| Peppers | Mar 3 | May 19 | May 26 | Jul 28 – Oct 6 | 60–90 |
| Pole Beans | Mar 17 | May 19 | May 26 | Jul 21 – Sep 15 | 55–70 |
| Potatoes | Mar 17 | May 19 | May 26 | Aug 4 – Oct 13 | 70–120 |
| Pumpkin | Apr 7 | May 19 | May 26 | Aug 25 – Oct 13 | 85–120 |
| Purslane | Apr 7 | Apr 28 | May 12 | Jun 23 – Jul 28 | 40–60 |
| Radicchio | Apr 7 | Apr 28 | May 12 | Jul 14 – Aug 18 | 60–80 |
| Radish | — | Apr 28 | — | May 26 – Jun 16 | 22–35 |
| Rhubarb | — | — | Jun 2 | — | 365–730 |
| Romanesco | Apr 7 | Apr 28 | May 12 | Jul 28 – Sep 8 | 75–100 |
| Rutabaga | — | Apr 28 | — | Jul 21 – Aug 25 | 80–100 |
| Salsify | — | Apr 28 | — | Aug 11 – Sep 22 | 100–130 |
| Savoy Cabbage | Apr 7 | Apr 28 | May 12 | Jul 21 – Sep 15 | 70–110 |
| Scallions | Apr 7 | Apr 28 | May 12 | Jul 7 – Aug 4 | 50–70 |
| Scarlet Runner Beans | Mar 17 | May 19 | May 26 | Jul 28 – Sep 1 | 60–80 |
| Shallot | Apr 7 | Apr 28 | May 12 | Aug 11 – Sep 29 | 90–120 |
| Shiso | Mar 24 | May 19 | May 26 | Jul 21 – Sep 15 | 50–70 |
| Snap Peas | Mar 17 | May 19 | May 26 | Jul 21 – Sep 15 | 55–70 |
| Snow Peas | Apr 7 | Apr 28 | May 12 | Jul 7 – Sep 1 | 50–65 |
| Soybeans | — | May 19 | — | Aug 11 – Oct 6 | 80–120 |
| Spaghetti Squash | Apr 7 | May 19 | May 26 | Aug 25 – Sep 22 | 85–100 |
| Spinach | Apr 7 | Apr 28 | May 12 | Jun 16 – Aug 18 | 35–50 |
| Squash (Summer) | Apr 7 | May 19 | May 26 | Jul 14 – Sep 15 | 45–65 |
| Squash (Winter) | Apr 7 | May 19 | May 26 | Aug 18 – Oct 13 | 80–120 |
| Sunchoke | — | — | May 26 | Sep 15 – Nov 10 | 110–150 |
| Sunflower | Mar 17 | May 19 | May 26 | Aug 4 – Sep 22 | 70–100 |
| Sweet Corn | — | May 19 | — | Jul 21 – Sep 1 | 60–90 |
| Sweet Potatoes | Mar 17 | May 19 | May 26 | Aug 25 – Oct 13 | 90–120 |
| Tatsoi | Apr 7 | Apr 28 | May 12 | Jun 16 – Jul 21 | 35–50 |
| Tomatillo | Mar 17 | May 19 | May 26 | Jul 28 – Oct 6 | 60–85 |
| Tomatoes | Mar 17 | May 19 | May 26 | Jul 28 – Oct 6 | 60–85 |
| Turnip | — | Apr 28 | — | Jun 9 – Jul 14 | 40–60 |
| Watercress | Apr 7 | Apr 28 | May 12 | Jun 23 – Jul 28 | 40–60 |
| Watermelon | Apr 7 | May 19 | May 26 | Aug 4 – Sep 22 | 70–100 |
| Wax Beans | — | May 19 | — | Jul 14 – Sep 8 | 50–65 |
| Winter Melon | Mar 17 | May 19 | May 26 | Aug 25 – Oct 13 | 90–120 |
| Yard Long Beans | Mar 17 | May 19 | May 26 | Jul 21 – Sep 1 | 55–80 |
| Zucchini | Apr 7 | May 19 | May 26 | Jul 14 – Sep 8 | 45–60 |
🍓 Fruits to Grow in Union County
27 fruits that grow well in Zone 5b with planting dates for Union County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 2 | Sep 1 – Nov 17 | 90–180 |
| Aronia | — | — | Jun 2 | — | 730–1095 |
| Blackberries | — | — | Jun 2 | — | 365–730 |
| Blueberries | — | — | Jun 2 | — | 730–1095 |
| Boysenberries | — | — | Jun 2 | — | 365–730 |
| Cantaloupe | — | — | Jun 2 | Aug 11 – Sep 15 | 70–90 |
| Che Fruit | — | — | Jun 2 | — | 1095–1825 |
| Cranberries | — | — | Jun 2 | — | 730–1095 |
| Currants | — | — | Jun 2 | — | 730–1095 |
| Elderberries | — | — | Jun 2 | — | 730–1095 |
| Goji Berries | — | — | Jun 2 | — | 730–1095 |
| Gooseberries | — | — | Jun 2 | — | 730–1095 |
| Grapes | — | — | Jun 2 | — | 730–1095 |
| Ground Cherry | — | — | Jun 2 | Aug 11 – Oct 6 | 65–80 |
| Hardy Kiwi | — | — | Jun 2 | — | 1095–1825 |
| Haskaps | — | — | Jun 2 | — | 730–1095 |
| Honeydew | — | — | Jun 2 | Aug 25 – Oct 6 | 80–110 |
| Jostaberry | — | — | Jun 2 | — | 730–1095 |
| Lingonberries | — | — | Jun 2 | — | 730–1095 |
| Medlar | — | — | Jun 2 | — | 1095–1825 |
| Mulberries | — | — | Jun 2 | — | 730–1825 |
| Pawpaw | — | — | Jun 2 | — | 1095–2555 |
| Persimmon | — | — | Jun 2 | — | 1095–2555 |
| Quince | — | — | Jun 2 | — | 1095–1825 |
| Raspberries | — | — | Jun 2 | — | 365–730 |
| Serviceberries | — | — | Jun 2 | — | 730–1095 |
| Strawberries | — | — | Jun 2 | Sep 1 – Nov 17 | 90–365 |
🌿 Herbs to Grow in Union County
37 herbs that grow well in Zone 5b with planting dates for Union County.
Show all 37 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 7 | Apr 28 | May 5 | — | 365–730 |
| Anise | Apr 7 | Apr 28 | May 5 | Aug 4 – Oct 20 | 90–120 |
| Basil | Mar 24 | May 19 | May 26 | Jul 21 – Sep 22 | 50–75 |
| Bee Balm | — | — | May 19 | Aug 18 – Nov 3 | 90–120 |
| Borage | Apr 7 | Apr 28 | May 5 | Jun 30 – Aug 18 | 50–60 |
| Caraway | Apr 7 | Apr 28 | May 5 | — | 365–450 |
| Catnip | — | — | May 19 | Jul 21 – Sep 22 | 60–80 |
| Chamomile | Apr 7 | Apr 28 | May 5 | Jul 7 – Sep 15 | 60–90 |
| Chervil | Apr 7 | Apr 28 | May 5 | Jun 16 – Aug 18 | 40–60 |
| Chives | — | — | May 19 | Jul 21 – Sep 29 | 60–90 |
| Cilantro | Apr 7 | Apr 28 | May 5 | Jun 16 – Aug 18 | 40–60 |
| Comfrey | — | — | May 19 | Jul 21 – Sep 29 | 60–90 |
| Cumin | Apr 7 | Apr 28 | May 5 | Aug 18 – Oct 20 | 100–120 |
| Dill | Apr 7 | Apr 28 | May 5 | Jun 16 – Aug 18 | 40–60 |
| Echinacea | — | — | May 19 | Sep 22 – Nov 3 | 120–180 |
| Epazote | Mar 24 | May 19 | May 26 | Jul 14 – Sep 8 | 45–60 |
| Fennel (herb) | Apr 7 | Apr 28 | May 5 | Jul 7 – Sep 15 | 60–90 |
| Feverfew | — | — | May 19 | Aug 18 – Nov 3 | 90–120 |
| Garlic Chives | — | — | May 19 | Jul 21 – Sep 29 | 60–90 |
| Horehound | — | — | May 19 | Aug 4 – Sep 29 | 75–90 |
| Hyssop | — | — | May 19 | Jul 28 – Sep 29 | 70–90 |
| Lavender | — | — | May 19 | Aug 18 – Nov 3 | 90–200 |
| Lemon Balm | — | — | May 19 | Jul 21 – Sep 8 | 60–70 |
| Lemon Thyme | — | — | May 19 | Jul 28 – Sep 29 | 70–90 |
| Lovage | — | — | May 19 | Jul 28 – Sep 29 | 70–90 |
| Mint | — | — | May 19 | Jul 21 – Sep 29 | 60–90 |
| Oregano | — | — | May 19 | Jul 21 – Sep 29 | 60–90 |
| Parsley | Apr 7 | Apr 28 | May 5 | Jul 7 – Sep 8 | 60–80 |
| Rue | — | — | May 19 | Jul 28 – Sep 29 | 70–90 |
| Sage | — | — | May 19 | Aug 4 – Sep 29 | 75–90 |
| Savory | — | — | May 19 | Jul 14 – Sep 8 | 50–70 |
| Sorrel | Apr 7 | Apr 28 | May 5 | Jun 16 – Aug 18 | 40–60 |
| Tarragon | — | — | May 19 | Jul 21 – Sep 29 | 60–90 |
| Thai Basil | Mar 24 | May 19 | May 26 | Jul 21 – Sep 22 | 50–75 |
| Thyme | — | — | May 19 | Jul 28 – Sep 29 | 70–90 |
| Valerian | — | — | May 19 | Sep 22 – Nov 3 | 120–180 |
| Yarrow | — | — | May 19 | Aug 18 – Nov 3 | 90–120 |
Monthly Planting Guide for Union County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Union County.
Frequently Asked Questions
What planting zone is Union County, OR?
Union County is in USDA Hardiness Zone 5b. 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 Union County, OR?
Based on 29 years of NOAA weather station data, the median last spring frost in Union County falls around May 12. In 8 out of 10 years, last frost lands between April 24 and June 8 — a 45-day window of variability. Use June 8 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Union County, OR?
The median first fall frost in Union County arrives around September 26. In cold years it can arrive as early as September 2; in mild years as late as October 19. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Union County?
Union County has a frost-free growing season of approximately 137 days. Focus on short-season varieties and start warm-season crops indoors 6–8 weeks before last frost. Climate records show the growing season is trending longer by about 2.18 days per decade.
What is the soil like in Union County for gardening?
Union County has predominantly Silt Loam soil with a pH range of 5.2–6.6 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Union County?
Union County has commercial agriculture that includes Wheat, Apples, Potatoes. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Union County a good location for home gardening?
Union County scores 53/100 (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 Union County gardeners in Zone 5b 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.
