Mercer County, PA — Planting Guide
Top priorities for Mercer County, Pennsylvania gardeners in May
Each item below is timed to Mercer County, Pennsylvania's frost dates and soil temperatures. Skip nothing, stress about nothing.
-
Time to transplant basil, cucumber, and kale
Your last frost (May 6) has passed. These warm-season crops can handle outdoor soil now.
-
Direct-sow basil, cucumber, and green beans
Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.
-
Bring in the radish, cress, and microgreens
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
June prep starts now
- Starting indoors: basil, cucumber, and kale
- First harvests: carrots, lettuce, and radish
Mercer County is in USDA Zone 6a. The average last spring frost is May 6 and the first fall frost is October 17, giving you a growing season of approximately 164 days.
At an elevation of 63 ft, Mercer County receives approximately 43.3 in of rainfall annually. Summer highs average 84°F with winter lows around 15°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 26 days year to year — ranging from April 25 in warm years to May 22 in cold years. The growing season is trending longer by about 0.81 days per decade. Mercer County scores 72/100 (Good) on the Microclimate Index.
🌡️ Zone
6a (°F to °F min)
❄️ Last Frost
May 6
🍂 First Frost
October 17
📅 Growing Season
164 days
⛰️ Elevation
63 ft
🌧️ Annual Rainfall
43.3 in
Monthly Watering Calendar
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 3.3 in | 11 days | — | None |
| Feb | 2.9 in | 10 days | — | None |
| Mar | 4 in | 10 days | — | None |
| Apr | 3.6 in | 9 days | 0.7 in | Moderate |
| May | 3.8 in | 10 days | 0.5 in | Low |
| Jun | 4.2 in | 9 days | 0.1 in | Low |
| Jul | 4.8 in | 10 days | — | Low |
| Aug | 3.5 in | 10 days | 0.8 in | Moderate |
| Sep | 3.1 in | 7 days | 1.2 in | Moderate |
| Oct | 3.1 in | 9 days | 1.2 in | Moderate |
| Nov | 3.5 in | 10 days | — | None |
| Dec | 3.4 in | 10 days | — | None |
Annual total: 43.2 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.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
5.1-6.5
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 22 | Oct 28 | 159 days |
| Cautious | May 13 | Oct 22 | 162 days |
| Average year | May 6 | Oct 17 | 164 days |
| Optimistic | Apr 29 | Oct 11 | 165 days |
| Aggressive (risky) | Apr 25 | Oct 6 | 164 days |
Not very — frost dates can vary by ±26 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 (0.8 days/decade). Historical frost dates are still reliable for planning.
Gardening Difficulty Score
Mercer County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in Mercer 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 Mercer County's climate and soil.
County Extension Office
Mercer County Penn State Extension Extension Office
Phone: 814-865-4028
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 Mercer County
Finding local nurseries & garden centers in Mercer County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Mercer 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 Mercer County PA" or "garden center Mercer 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 Mercer County PA" or check your extension office and local parks department. Facebook groups like "Mercer County Gardeners" or "Pennsylvania 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 hours
Summer solstice daylight
Shortest Day
9 hours
Winter solstice daylight
Peak Sun Hours
8.5 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 | 9.3 hr | 3.6 hr | Short day |
| February | 10.4 hr | 4.4 hr | Short day |
| March | 11.7 hr | 5.3 hr | Short day |
| April | 13.1 hr | 6.3 hr | Neutral |
| May | 14.3 hr | 7.7 hr | Long day |
| June | 15 hr | 8.2 hr | Long day |
| July | 14.7 hr | 8.5 hr | Long day |
| August | 13.7 hr | 7.2 hr | Neutral |
| September | 12.3 hr | 6.4 hr | Neutral |
| October | 10.9 hr | 5 hr | Short day |
| November | 9.6 hr | 3.7 hr | Short day |
| December | 9 hr | 3.1 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
Jun
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 | 24°F | 31°F | ❄️ Dormant | ~36 weeks |
| Feb | 24°F | 30°F | ❄️ Dormant | ~36 weeks |
| Mar | 34°F | 35°F | ❄️ Dormant | ~36 weeks |
| Apr | 45°F | 43°F | 🐢 Slow | ~24 weeks |
| May | 58°F | 54°F | ♻️ Active | ~14 weeks |
| Jun | 70°F | 63°F | 🔥 Peak | ~8 weeks |
| Jul | 79°F | 71°F | 🔥 Peak | ~8 weeks |
| Aug | 77°F | 74°F | 🔥 Peak | ~8 weeks |
| Sep | 69°F | 68°F | 🔥 Peak | ~8 weeks |
| Oct | 56°F | 60°F | ♻️ Active | ~14 weeks |
| Nov | 44°F | 49°F | 🐢 Slow | ~24 weeks |
| Dec | 31°F | 38°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 Mercer 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
Moderate — watch for mildew and blight during wet periods.
Seasonal Risk
View 5 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | Moderate | May, Jun, Jul, Aug |
| Japanese beetles | Moderate | Jun, Jul, Aug |
| Squash bugs | Moderate | Jun, Jul, Aug |
| Tomato hornworms | Low | Jul, Aug |
| Cabbage loopers | Low | May, Jun, Jul, Aug |
Organic pest management tips
- Use row covers on susceptible crops during peak pest months
- Apply neem oil preventatively every 7-14 days during active pest season
- Interplant with strong-scented herbs (basil, marigold) to confuse pests
- Hand-pick larger pests (beetles, caterpillars) in early morning when they're sluggish
- Practice crop rotation — never plant the same family in the same spot within 3 years
Cover Crops for Mercer 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 7 | Aug 8 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Sorghum-sudan grass | May 10 | Aug 22 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Apr 8 | Aug 22 | ✓ 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 | Sep 19 | — | 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 | Aug 5 | Apr 15 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Daikon radish | Sep 4 | Apr 22 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Aug 9 | Apr 22 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Sep 7 | Apr 22 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 20 | Apr 22 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jul 25 | Apr 15 | — | 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: 12 mph Summer: 8 mph
Fall: 9 mph Winter: 12 mph
Prevailing wind: W. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5.4/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Moderate
Some terrain variation (476 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
21,530 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 750 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Mar, May, Jun, Jul
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Feb, Sep, Oct
Dry months when you'll rely on stored water — size your storage for this gap.
Rainwater collection tips for your area
- Your county receives approximately 43.2 inches of rain per year
- A 1,000 sq ft roof can collect roughly 21,530 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Feb, Sep, Oct)
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in Mercer County
Soil Type
Silt Loam
Soil pH 5.1–6.5 · Moderately 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. (43.3 in. annual rainfall)
Season Tips
164-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.
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
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 Mercer County
108 vegetables that grow well in Zone 6a with planting dates for Mercer County.
Show all 108 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 1 | May 13 | May 20 | Aug 12 – Sep 16 | 80–100 |
| Amaranth | Mar 11 | May 13 | May 20 | Aug 19 – Oct 7 | 90–120 |
| Arugula | Apr 1 | Apr 22 | May 6 | Jun 10 – Aug 12 | 30–50 |
| Asparagus | — | — | May 20 | — | 730–1095 |
| Beets | — | Apr 22 | — | Jun 17 – Jul 15 | 50–70 |
| Belgian Endive | Apr 1 | Apr 22 | May 6 | Aug 26 – Oct 21 | 110–150 |
| Bitter Melon | Mar 11 | May 13 | May 20 | Jul 22 – Sep 2 | 60–90 |
| Black Beans | — | May 13 | — | Aug 12 – Sep 30 | 90–120 |
| Bok Choy | Apr 1 | Apr 22 | May 6 | Jun 17 – Jul 22 | 40–60 |
| Broccoli | Apr 1 | Apr 22 | May 6 | Jul 8 – Aug 19 | 60–90 |
| Broccoli Rabe | Apr 1 | Apr 22 | May 6 | Jun 17 – Jul 22 | 40–60 |
| Brussels Sprouts | Apr 1 | Apr 22 | May 6 | Aug 5 – Sep 30 | 90–130 |
| Butternut Squash | Apr 1 | May 13 | May 20 | Aug 19 – Sep 23 | 85–110 |
| Cabbage | Apr 1 | Apr 22 | May 6 | Jul 8 – Sep 2 | 60–100 |
| Calabash | Mar 11 | May 13 | May 20 | Aug 12 – Oct 7 | 80–120 |
| Carrots | — | Apr 22 | — | Jun 24 – Jul 29 | 60–80 |
| Cauliflower | Apr 1 | Apr 22 | May 6 | Jul 1 – Sep 2 | 55–100 |
| Celeriac | Apr 1 | Apr 22 | May 6 | Aug 19 – Sep 23 | 100–120 |
| Celery | Apr 1 | Apr 22 | May 6 | Jul 29 – Sep 23 | 80–120 |
| Celtuce | Apr 1 | Apr 22 | May 6 | Jul 8 – Aug 19 | 60–90 |
| Chard | Apr 1 | Apr 22 | May 6 | Jul 1 – Aug 19 | 50–60 |
| Chickpeas | Apr 1 | Apr 22 | May 6 | Jul 29 – Sep 9 | 80–110 |
| Chicory | Apr 1 | Apr 22 | May 6 | Jul 8 – Aug 19 | 60–85 |
| Chinese Cabbage | Apr 1 | Apr 22 | May 6 | Jul 1 – Jul 29 | 50–70 |
| Christmas Lima Beans | Mar 11 | May 13 | May 20 | Aug 12 – Sep 16 | 80–100 |
| Collard Greens | Apr 1 | Apr 22 | May 6 | Jul 1 – Sep 2 | 55–75 |
| Corn | — | May 13 | — | Jul 15 – Sep 9 | 60–100 |
| Cowpeas | — | May 13 | — | Jul 15 – Aug 26 | 60–90 |
| Cress | Apr 1 | Apr 22 | May 6 | May 20 – Jun 10 | 14–21 |
| Crookneck Squash | Apr 1 | May 13 | May 20 | Jul 8 – Aug 5 | 45–60 |
| Crosne | — | Apr 22 | — | Sep 23 – Nov 4 | 150–200 |
| Cucumber | Apr 1 | May 13 | May 20 | Jul 15 – Sep 9 | 50–70 |
| Daikon | — | Apr 22 | — | Jun 17 – Jul 15 | 50–70 |
| Delicata Squash | Apr 1 | May 13 | May 20 | Aug 12 – Sep 16 | 80–100 |
| Edamame | — | May 13 | — | Jul 29 – Sep 9 | 75–100 |
| Eggplant | Feb 25 | May 13 | May 20 | Jul 29 – Sep 30 | 65–85 |
| Endive | Apr 1 | Apr 22 | May 6 | Jun 24 – Jul 29 | 45–65 |
| Escarole | Apr 1 | Apr 22 | May 6 | Jul 1 – Jul 29 | 50–70 |
| Fava Beans | Apr 1 | Apr 22 | May 6 | Jul 22 – Sep 2 | 75–100 |
| Fennel | Mar 11 | May 13 | May 20 | Jul 22 – Sep 2 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | May 13 | — | Jul 8 – Sep 2 | 50–65 |
| Horseradish | — | — | May 20 | Sep 23 – Dec 2 | 120–180 |
| Hot Peppers | Feb 25 | May 13 | May 20 | Jul 29 – Nov 4 | 70–120 |
| Hubbard Squash | Apr 1 | May 13 | May 20 | Sep 2 – Oct 7 | 100–120 |
| Kabocha | Apr 1 | May 13 | May 20 | Aug 19 – Sep 16 | 85–100 |
| Kai Lan | Apr 1 | Apr 22 | May 6 | Jun 24 – Jul 22 | 45–60 |
| Kale | Apr 1 | Apr 22 | May 6 | Jul 1 – Aug 26 | 50–70 |
| Kidney Beans | — | May 13 | — | Aug 12 – Sep 16 | 85–110 |
| Kohlrabi | Apr 1 | Apr 22 | May 6 | Jun 24 – Jul 29 | 45–65 |
| Komatsuna | Apr 1 | Apr 22 | May 6 | Jun 10 – Jul 15 | 35–50 |
| Leeks | Apr 1 | Apr 22 | May 6 | Aug 5 – Oct 21 | 90–150 |
| Lentils | Apr 1 | Apr 22 | May 6 | Jul 29 – Sep 9 | 80–110 |
| Lettuce | Apr 1 | Apr 22 | May 6 | Jun 10 – Aug 19 | 30–60 |
| Lima Beans | — | May 13 | — | Jul 15 – Aug 26 | 60–90 |
| Loofah | Mar 11 | May 13 | May 20 | Sep 2 – Nov 4 | 100–150 |
| Luffa | Mar 11 | May 13 | May 20 | Aug 19 – Nov 4 | 90–150 |
| Mache | Apr 1 | Apr 22 | May 6 | Jun 17 – Jul 22 | 40–60 |
| Melon | Apr 1 | May 13 | May 20 | Jul 29 – Sep 16 | 70–100 |
| Microgreens | Apr 1 | Apr 22 | May 6 | May 13 – Jun 10 | 7–21 |
| Mitsuba | Apr 1 | Apr 22 | Apr 29 | Jun 24 – Aug 19 | 50–70 |
| Mizuna | Apr 1 | Apr 22 | May 6 | Jun 10 – Jul 8 | 30–45 |
| Mustard Greens | Apr 1 | Apr 22 | May 6 | Jun 10 – Aug 12 | 30–50 |
| Napa Cabbage | Apr 1 | Apr 22 | May 6 | Jul 1 – Aug 5 | 55–75 |
| New Zealand Spinach | Mar 11 | May 13 | May 20 | Jul 15 – Aug 12 | 55–70 |
| Okra | Mar 11 | May 13 | May 20 | Jul 15 – Sep 9 | 50–65 |
| Onion | Apr 1 | Apr 22 | May 6 | Aug 5 – Sep 23 | 90–120 |
| Pac Choi | Apr 1 | Apr 22 | May 6 | Jun 17 – Jul 15 | 40–55 |
| Parsnip | — | Apr 22 | — | Aug 5 – Sep 16 | 100–130 |
| Patty Pan Squash | Apr 1 | May 13 | May 20 | Jul 8 – Aug 5 | 45–60 |
| Peas | Apr 1 | Apr 22 | May 6 | Jul 1 – Aug 26 | 55–70 |
| Peppers | Feb 25 | May 13 | May 20 | Jul 22 – Sep 30 | 60–90 |
| Pole Beans | Mar 11 | May 13 | May 20 | Jul 15 – Sep 9 | 55–70 |
| Potatoes | Mar 11 | May 13 | May 20 | Jul 29 – Oct 7 | 70–120 |
| Pumpkin | Apr 1 | May 13 | May 20 | Aug 19 – Oct 7 | 85–120 |
| Purslane | Apr 1 | Apr 22 | May 6 | Jun 17 – Jul 22 | 40–60 |
| Radicchio | Apr 1 | Apr 22 | May 6 | Jul 8 – Aug 12 | 60–80 |
| Radish | — | Apr 22 | — | May 20 – Jun 10 | 22–35 |
| Rhubarb | — | — | May 27 | — | 365–730 |
| Romanesco | Apr 1 | Apr 22 | May 6 | Jul 22 – Sep 2 | 75–100 |
| Rutabaga | — | Apr 22 | — | Jul 15 – Aug 19 | 80–100 |
| Salsify | — | Apr 22 | — | Aug 5 – Sep 16 | 100–130 |
| Savoy Cabbage | Apr 1 | Apr 22 | May 6 | Jul 15 – Sep 9 | 70–110 |
| Scallions | Apr 1 | Apr 22 | May 6 | Jul 1 – Jul 29 | 50–70 |
| Scarlet Runner Beans | Mar 11 | May 13 | May 20 | Jul 22 – Aug 26 | 60–80 |
| Shallot | Apr 1 | Apr 22 | May 6 | Aug 5 – Sep 23 | 90–120 |
| Shiso | Mar 18 | May 13 | May 20 | Jul 15 – Sep 9 | 50–70 |
| Snap Peas | Mar 11 | May 13 | May 20 | Jul 15 – Sep 9 | 55–70 |
| Snow Peas | Apr 1 | Apr 22 | May 6 | Jul 1 – Aug 26 | 50–65 |
| Soybeans | — | May 13 | — | Aug 5 – Sep 30 | 80–120 |
| Spaghetti Squash | Apr 1 | May 13 | May 20 | Aug 19 – Sep 16 | 85–100 |
| Spinach | Apr 1 | Apr 22 | May 6 | Jun 10 – Aug 12 | 35–50 |
| Squash (Summer) | Apr 1 | May 13 | May 20 | Jul 8 – Sep 9 | 45–65 |
| Squash (Winter) | Apr 1 | May 13 | May 20 | Aug 12 – Oct 7 | 80–120 |
| Sunchoke | — | — | May 20 | Sep 9 – Nov 4 | 110–150 |
| Sunflower | Mar 11 | May 13 | May 20 | Jul 29 – Sep 16 | 70–100 |
| Sweet Corn | — | May 13 | — | Jul 15 – Aug 26 | 60–90 |
| Sweet Potatoes | Mar 11 | May 13 | May 20 | Aug 19 – Oct 7 | 90–120 |
| Tatsoi | Apr 1 | Apr 22 | May 6 | Jun 10 – Jul 15 | 35–50 |
| Tomatillo | Mar 11 | May 13 | May 20 | Jul 22 – Sep 30 | 60–85 |
| Tomatoes | Mar 11 | May 13 | May 20 | Jul 22 – Sep 30 | 60–85 |
| Turnip | — | Apr 22 | — | Jun 3 – Jul 8 | 40–60 |
| Watercress | Apr 1 | Apr 22 | May 6 | Jun 17 – Jul 22 | 40–60 |
| Watermelon | Apr 1 | May 13 | May 20 | Jul 29 – Sep 16 | 70–100 |
| Wax Beans | — | May 13 | — | Jul 8 – Sep 2 | 50–65 |
| Winter Melon | Mar 11 | May 13 | May 20 | Aug 19 – Oct 7 | 90–120 |
| Yard Long Beans | Mar 11 | May 13 | May 20 | Jul 15 – Aug 26 | 55–80 |
| Zucchini | Apr 1 | May 13 | May 20 | Jul 8 – Sep 2 | 45–60 |
🍓 Fruits to Grow in Mercer County
27 fruits that grow well in Zone 6a with planting dates for Mercer County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | May 27 | Aug 26 – Dec 9 | 90–180 |
| Aronia | — | — | May 27 | — | 730–1095 |
| Blackberries | — | — | May 27 | — | 365–730 |
| Blueberries | — | — | May 27 | — | 730–1095 |
| Boysenberries | — | — | May 27 | — | 365–730 |
| Cantaloupe | — | — | May 27 | Aug 5 – Sep 9 | 70–90 |
| Che Fruit | — | — | May 27 | — | 1095–1825 |
| Cranberries | — | — | May 27 | — | 730–1095 |
| Currants | — | — | May 27 | — | 730–1095 |
| Elderberries | — | — | May 27 | — | 730–1095 |
| Goji Berries | — | — | May 27 | — | 730–1095 |
| Gooseberries | — | — | May 27 | — | 730–1095 |
| Grapes | — | — | May 27 | — | 730–1095 |
| Ground Cherry | — | — | May 27 | Aug 5 – Sep 30 | 65–80 |
| Hardy Kiwi | — | — | May 27 | — | 1095–1825 |
| Haskaps | — | — | May 27 | — | 730–1095 |
| Honeydew | — | — | May 27 | Aug 19 – Sep 30 | 80–110 |
| Jostaberry | — | — | May 27 | — | 730–1095 |
| Lingonberries | — | — | May 27 | — | 730–1095 |
| Medlar | — | — | May 27 | — | 1095–1825 |
| Mulberries | — | — | May 27 | — | 730–1825 |
| Pawpaw | — | — | May 27 | — | 1095–2555 |
| Persimmon | — | — | May 27 | — | 1095–2555 |
| Quince | — | — | May 27 | — | 1095–1825 |
| Raspberries | — | — | May 27 | — | 365–730 |
| Serviceberries | — | — | May 27 | — | 730–1095 |
| Strawberries | — | — | May 27 | Aug 26 – Dec 9 | 90–365 |
🌿 Herbs to Grow in Mercer County
38 herbs that grow well in Zone 6a with planting dates for Mercer County.
Show all 38 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 1 | Apr 22 | Apr 29 | — | 365–730 |
| Anise | Apr 1 | Apr 22 | Apr 29 | Jul 29 – Oct 14 | 90–120 |
| Basil | Mar 18 | May 13 | May 20 | Jul 15 – Sep 16 | 50–75 |
| Bee Balm | — | — | May 13 | Aug 12 – Oct 28 | 90–120 |
| Borage | Apr 1 | Apr 22 | Apr 29 | Jun 24 – Aug 12 | 50–60 |
| Caraway | Apr 1 | Apr 22 | Apr 29 | — | 365–450 |
| Catnip | — | — | May 13 | Jul 15 – Sep 16 | 60–80 |
| Chamomile | Apr 1 | Apr 22 | Apr 29 | Jul 1 – Sep 9 | 60–90 |
| Chervil | Apr 1 | Apr 22 | Apr 29 | Jun 10 – Aug 12 | 40–60 |
| Chives | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Cilantro | Apr 1 | Apr 22 | Apr 29 | Jun 10 – Aug 12 | 40–60 |
| Comfrey | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Cumin | Apr 1 | Apr 22 | Apr 29 | Aug 12 – Oct 14 | 100–120 |
| Dill | Apr 1 | Apr 22 | Apr 29 | Jun 10 – Aug 12 | 40–60 |
| Echinacea | — | — | May 13 | Sep 16 – Nov 25 | 120–180 |
| Epazote | Mar 18 | May 13 | May 20 | Jul 8 – Sep 2 | 45–60 |
| Fennel (herb) | Apr 1 | Apr 22 | Apr 29 | Jul 1 – Sep 9 | 60–90 |
| Feverfew | — | — | May 13 | Aug 12 – Oct 28 | 90–120 |
| Garlic Chives | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Horehound | — | — | May 13 | Jul 29 – Sep 23 | 75–90 |
| Hyssop | — | — | May 13 | Jul 22 – Sep 23 | 70–90 |
| Lavender | — | — | May 13 | Aug 12 – Nov 25 | 90–200 |
| Lemon Balm | — | — | May 13 | Jul 15 – Sep 2 | 60–70 |
| Lemon Thyme | — | — | May 13 | Jul 22 – Sep 23 | 70–90 |
| Lovage | — | — | May 13 | Jul 22 – Sep 23 | 70–90 |
| Marjoram | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Mint | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Oregano | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Parsley | Apr 1 | Apr 22 | Apr 29 | Jul 1 – Sep 2 | 60–80 |
| Rue | — | — | May 13 | Jul 22 – Sep 23 | 70–90 |
| Sage | — | — | May 13 | Jul 29 – Sep 23 | 75–90 |
| Savory | — | — | May 13 | Jul 8 – Sep 2 | 50–70 |
| Sorrel | Apr 1 | Apr 22 | Apr 29 | Jun 10 – Aug 12 | 40–60 |
| Tarragon | — | — | May 13 | Jul 15 – Sep 23 | 60–90 |
| Thai Basil | Mar 18 | May 13 | May 20 | Jul 15 – Sep 16 | 50–75 |
| Thyme | — | — | May 13 | Jul 22 – Sep 23 | 70–90 |
| Valerian | — | — | May 13 | Sep 16 – Nov 25 | 120–180 |
| Yarrow | — | — | May 13 | Aug 12 – Oct 28 | 90–120 |
Monthly Planting Guide for Mercer County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Mercer County.
Frequently Asked Questions
What planting zone is Mercer County, PA?
Mercer County is in USDA Hardiness Zone 6a. 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 Mercer County, PA?
Based on 31 years of NOAA weather station data, the median last spring frost in Mercer County falls around May 6. In 8 out of 10 years, last frost lands between April 25 and May 22 — a 26-day window of variability. Use May 22 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Mercer County, PA?
The median first fall frost in Mercer County arrives around October 17. In cold years it can arrive as early as October 6; in mild years as late as October 28. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Mercer County?
Mercer County has a frost-free growing season of approximately 164 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 longer by about 0.81 days per decade.
What is the soil like in Mercer County for gardening?
Mercer County has predominantly Silt Loam soil with a pH range of 5.1–6.5 and Moderately Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Mercer County?
Mercer County has commercial agriculture that includes Dairy, Hay, Corn, Apples, Sweet Corn. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Mercer County a good location for home gardening?
Mercer County scores 72/100 (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 Mercer County Garden Planner — Free
A 24-page printable planner built for Mercer County (Zone 6a). 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