Mercer County, NJ — Planting Guide
Mercer County is in USDA Zone 7a. The average last spring frost is April 12 and the first fall frost is October 29, giving you a growing season of approximately 200 days.
At an elevation of 4 ft, Mercer County receives approximately 45.5 in of rainfall annually. Summer highs average 90°F with winter lows around 30°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 35 days year to year — ranging from March 26 in warm years to May 1 in cold years. The growing season is trending longer by about 0.79 days per decade. Mercer County scores 75/100 (Good) on the Microclimate Index.
🌡️ Zone
7a (0°F to 5°F min)
❄️ Last Frost
April 12
🍂 First Frost
October 29
📅 Growing Season
200 days
⛰️ Elevation
4 ft
🌧️ Annual Rainfall
45.5 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 | 3.1 in | 11 days | — | None |
| Feb | 3.3 in | 11 days | — | None |
| Mar | 4.1 in | 10 days | 0.2 in | Low |
| Apr | 4.1 in | 11 days | 0.2 in | Low |
| May | 4.1 in | 11 days | 0.2 in | Low |
| Jun | 3.8 in | 9 days | 0.5 in | Low |
| Jul | 4.8 in | 9 days | — | Low |
| Aug | 4.1 in | 11 days | 0.2 in | Low |
| Sep | 3.5 in | 8 days | 0.8 in | Moderate |
| Oct | 3.8 in | 9 days | 0.5 in | Low |
| Nov | 3.8 in | 11 days | — | None |
| Dec | 3 in | 10 days | — | None |
Annual total: 45.5 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
5-6.7
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) | May 1 | Nov 12 | 195 days |
| Cautious | Apr 22 | Nov 4 | 196 days |
| Average year | Apr 12 | Oct 29 | 200 days |
| Optimistic | Apr 5 | Oct 18 | 196 days |
| Aggressive (risky) | Mar 26 | Oct 10 | 198 days |
Not very — frost dates can vary by ±35 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 Rutgers Cooperative Extension Extension Office
Phone: 848-932-3610
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 NJ" 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 NJ" or check your extension office and local parks department. Facebook groups like "Mercer County Gardeners" or "New Jersey 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
14.9 hours
Summer solstice daylight
Shortest Day
9.1 hours
Winter solstice daylight
Peak Sun Hours
8.7 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 | 9.4 hr | 3.6 hr | Short day |
| February | 10.5 hr | 4.5 hr | Short day |
| March | 11.7 hr | 5.4 hr | Short day |
| April | 13.1 hr | 6.6 hr | Neutral |
| May | 14.2 hr | 7.6 hr | Long day |
| June | 14.9 hr | 8.1 hr | Long day |
| July | 14.6 hr | 8.7 hr | Long day |
| August | 13.6 hr | 7.7 hr | Neutral |
| September | 12.3 hr | 6.4 hr | Neutral |
| October | 10.9 hr | 5.1 hr | Short day |
| November | 9.7 hr | 3.6 hr | Short day |
| December | 9.1 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 May 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 | 38°F | 46°F | ❄️ Dormant | ~36 weeks |
| Feb | 40°F | 45°F | ❄️ Dormant | ~36 weeks |
| Mar | 47°F | 48°F | 🐢 Slow | ~24 weeks |
| Apr | 58°F | 57°F | ♻️ Active | ~14 weeks |
| May | 68°F | 64°F | 🔥 Peak | ~8 weeks |
| Jun | 77°F | 72°F | 🔥 Peak | ~8 weeks |
| Jul | 86°F | 79°F | 🔥 Peak | ~8 weeks |
| Aug | 87°F | 84°F | 🔥 Peak | ~8 weeks |
| Sep | 79°F | 78°F | 🔥 Peak | ~8 weeks |
| Oct | 69°F | 71°F | 🔥 Peak | ~8 weeks |
| Nov | 57°F | 62°F | ♻️ Active | ~14 weeks |
| Dec | 43°F | 50°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 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
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 |
| Japanese beetles | Moderate | Jun, Jul, Aug |
| Squash vine borers | High | May, Jun, Jul |
| Stink bugs | Moderate | May, Jun, Jul, Aug, Sep |
| Whiteflies | Moderate | Jun, Jul, Aug, Sep |
| Spider mites | Moderate | Jul, Aug |
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 Mercer 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 18 | Aug 27 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Cowpeas (southern peas) | Apr 18 | Aug 20 | ✓ Yes | Excellent nitrogen fixer for warm climates, edible |
| Sorghum-sudan grass | Apr 18 | Aug 27 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Mar 17 | Sep 3 | ✓ 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 2 | Oct 1 | — | 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 31 | Mar 29 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Crimson clover | Aug 20 | Mar 22 | ✓ Yes | Fixes nitrogen, attracts pollinators in spring |
| Daikon radish | Sep 20 | Mar 22 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Aug 5 | Mar 22 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Sep 18 | Mar 29 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Aug 2 | Mar 22 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Aug 7 | Mar 22 | — | 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: 15 mph Summer: 12 mph
Fall: 12 mph Winter: 17 mph
Prevailing wind: W. Windy area — plant a windbreak hedge on the W side of your garden.
Windbreak Benefit
7.4/10
Strongly recommended — a windbreak (fence, hedge, or row of tall crops like corn or sunflowers) will significantly improve garden yields.
Frost Pocket Risk
Low
Relatively flat terrain (230 ft range). Frost pocket risk is minimal — garden placement is flexible.
Rainwater Harvesting Potential
How much water you can collect, when to collect it, and what size system you need for your garden.
Annual Collection
22,677 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 500 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Mar, Apr, May, Jul
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Jan, Feb, Dec
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 45.5 inches of rain per year
- A 1,000 sq ft roof can collect roughly 22,677 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Jan, Feb, Dec)
- 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 5–6.7 · Moderately Well Drained drainage
Good candidate for raised beds to maximise drainage and extend the season.
Watering Needs
Drought stress: 1.5/10
Mercer County has very low drought pressure. Natural rainfall usually meets garden needs — water only during extended dry spells.
Season Tips
200-day frost-free season
Plenty of time for warm-season crops. Start heat-lovers indoors 6–8 weeks before last frost to maximise your harvest window.
Free Garden Planner
Plan your entire garden season — organize planting dates, track what you're growing, and know exactly when to start seeds, transplant, and harvest.
Recommended for Your Garden
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Get instant, accurate soil pH readings to fine-tune your amendments.
Boost soil fertility and structure with rich, well-aged organic compost.
🥬 Vegetables to Grow in Mercer County
113 vegetables that grow well in Zone 7a with planting dates for Mercer County.
Show all 113 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Mar 15 | Apr 19 | Apr 26 | Jul 19 – Aug 23 | 80–100 |
| Amaranth | Feb 22 | Apr 19 | Apr 26 | Jul 26 – Sep 13 | 90–120 |
| Artichoke | — | — | Apr 26 | Aug 30 – Nov 8 | 120–180 |
| Arugula | Mar 8 | Mar 29 | Apr 12 | May 17 – Jul 19 | 30–50 |
| Asparagus | — | — | Apr 26 | — | 730–1095 |
| Beets | — | Mar 29 | — | May 24 – Jun 21 | 50–70 |
| Belgian Endive | Mar 8 | Mar 29 | Apr 12 | Aug 2 – Sep 27 | 110–150 |
| Bitter Melon | Feb 22 | Apr 19 | Apr 26 | Jun 28 – Aug 9 | 60–90 |
| Black Beans | — | Apr 19 | — | Jul 19 – Sep 6 | 90–120 |
| Bok Choy | Mar 8 | Mar 29 | Apr 12 | May 24 – Jun 28 | 40–60 |
| Broccoli | Mar 8 | Mar 29 | Apr 12 | Jun 14 – Jul 26 | 60–90 |
| Broccoli Rabe | Mar 8 | Mar 29 | Apr 12 | May 24 – Jun 28 | 40–60 |
| Brussels Sprouts | Mar 8 | Mar 29 | Apr 12 | Jul 12 – Sep 6 | 90–130 |
| Butternut Squash | Mar 15 | Apr 19 | Apr 26 | Jul 26 – Aug 30 | 85–110 |
| Cabbage | Mar 8 | Mar 29 | Apr 12 | Jun 14 – Aug 9 | 60–100 |
| Calabash | Feb 22 | Apr 19 | Apr 26 | Jul 19 – Sep 13 | 80–120 |
| Cardoon | — | — | Apr 26 | Aug 30 – Oct 11 | 120–150 |
| Carrots | — | Mar 29 | — | May 31 – Jul 5 | 60–80 |
| Cauliflower | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Aug 9 | 55–100 |
| Celeriac | Mar 8 | Mar 29 | Apr 12 | Jul 26 – Aug 30 | 100–120 |
| Celery | Mar 8 | Mar 29 | Apr 12 | Jul 5 – Aug 30 | 80–120 |
| Celtuce | Mar 8 | Mar 29 | Apr 12 | Jun 14 – Jul 26 | 60–90 |
| Chard | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Jul 26 | 50–60 |
| Chayote | Feb 22 | Apr 19 | Apr 26 | Aug 30 – Nov 8 | 120–180 |
| Chickpeas | Mar 8 | Mar 29 | Apr 12 | Jul 5 – Aug 16 | 80–110 |
| Chicory | Mar 8 | Mar 29 | Apr 12 | Jun 14 – Jul 26 | 60–85 |
| Chinese Cabbage | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Jul 5 | 50–70 |
| Christmas Lima Beans | Feb 22 | Apr 19 | Apr 26 | Jul 19 – Aug 23 | 80–100 |
| Collard Greens | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Aug 9 | 55–75 |
| Corn | — | Apr 19 | — | Jun 21 – Aug 16 | 60–100 |
| Cowpeas | — | Apr 19 | — | Jun 21 – Aug 2 | 60–90 |
| Cress | Mar 8 | Mar 29 | Apr 12 | Apr 26 – May 17 | 14–21 |
| Crookneck Squash | Mar 15 | Apr 19 | Apr 26 | Jun 14 – Jul 12 | 45–60 |
| Crosne | — | Mar 29 | — | Aug 30 – Nov 1 | 150–200 |
| Cucumber | Mar 15 | Apr 19 | Apr 26 | Jun 21 – Aug 16 | 50–70 |
| Daikon | — | Mar 29 | — | May 24 – Jun 21 | 50–70 |
| Delicata Squash | Mar 15 | Apr 19 | Apr 26 | Jul 19 – Aug 23 | 80–100 |
| Edamame | — | Apr 19 | — | Jul 5 – Aug 16 | 75–100 |
| Eggplant | Feb 8 | Apr 19 | Apr 26 | Jul 5 – Sep 6 | 65–85 |
| Endive | Mar 8 | Mar 29 | Apr 12 | May 31 – Jul 5 | 45–65 |
| Escarole | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Jul 5 | 50–70 |
| Fava Beans | Mar 8 | Mar 29 | Apr 12 | Jun 28 – Aug 9 | 75–100 |
| Fennel | Feb 22 | Apr 19 | Apr 26 | Jun 28 – Aug 9 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Apr 19 | — | Jun 14 – Aug 9 | 50–65 |
| Horseradish | — | — | Apr 26 | Aug 30 – Nov 8 | 120–180 |
| Hot Peppers | Feb 8 | Apr 19 | Apr 26 | Jul 5 – Oct 11 | 70–120 |
| Hubbard Squash | Mar 15 | Apr 19 | Apr 26 | Aug 9 – Sep 13 | 100–120 |
| Jicama | Feb 22 | Apr 19 | Apr 26 | Aug 30 – Nov 8 | 120–180 |
| Kabocha | Mar 15 | Apr 19 | Apr 26 | Jul 26 – Aug 23 | 85–100 |
| Kai Lan | Mar 8 | Mar 29 | Apr 12 | May 31 – Jun 28 | 45–60 |
| Kale | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Aug 2 | 50–70 |
| Kidney Beans | — | Apr 19 | — | Jul 19 – Aug 23 | 85–110 |
| Kohlrabi | Mar 8 | Mar 29 | Apr 12 | May 31 – Jul 5 | 45–65 |
| Komatsuna | Mar 8 | Mar 29 | Apr 12 | May 17 – Jun 21 | 35–50 |
| Leeks | Mar 8 | Mar 29 | Apr 12 | Jul 12 – Sep 27 | 90–150 |
| Lentils | Mar 8 | Mar 29 | Apr 12 | Jul 5 – Aug 16 | 80–110 |
| Lettuce | Mar 8 | Mar 29 | Apr 12 | May 17 – Jul 26 | 30–60 |
| Lima Beans | — | Apr 19 | — | Jun 21 – Aug 2 | 60–90 |
| Loofah | Feb 22 | Apr 19 | Apr 26 | Aug 9 – Oct 11 | 100–150 |
| Luffa | Feb 22 | Apr 19 | Apr 26 | Jul 26 – Oct 11 | 90–150 |
| Mache | Mar 8 | Mar 29 | Apr 12 | May 24 – Jun 28 | 40–60 |
| Malabar Spinach | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Jul 19 | 55–70 |
| Melon | Mar 15 | Apr 19 | Apr 26 | Jul 5 – Aug 23 | 70–100 |
| Microgreens | Mar 8 | Mar 29 | Apr 12 | Apr 19 – May 17 | 7–21 |
| Mitsuba | Mar 8 | Mar 29 | Apr 5 | May 31 – Jul 26 | 50–70 |
| Mizuna | Mar 8 | Mar 29 | Apr 12 | May 17 – Jun 14 | 30–45 |
| Mustard Greens | Mar 8 | Mar 29 | Apr 12 | May 17 – Jul 19 | 30–50 |
| Napa Cabbage | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Jul 12 | 55–75 |
| New Zealand Spinach | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Jul 19 | 55–70 |
| Okra | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 16 | 50–65 |
| Onion | Mar 8 | Mar 29 | Apr 12 | Jul 12 – Aug 30 | 90–120 |
| Pac Choi | Mar 8 | Mar 29 | Apr 12 | May 24 – Jun 21 | 40–55 |
| Parsnip | — | Mar 29 | — | Jul 12 – Aug 23 | 100–130 |
| Patty Pan Squash | Mar 15 | Apr 19 | Apr 26 | Jun 14 – Jul 12 | 45–60 |
| Peas | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Aug 2 | 55–70 |
| Peppers | Feb 8 | Apr 19 | Apr 26 | Jun 28 – Sep 6 | 60–90 |
| Pole Beans | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 16 | 55–70 |
| Potatoes | Feb 22 | Apr 19 | Apr 26 | Jul 5 – Sep 13 | 70–120 |
| Pumpkin | Mar 15 | Apr 19 | Apr 26 | Jul 26 – Sep 13 | 85–120 |
| Purslane | Mar 8 | Mar 29 | Apr 12 | May 24 – Jun 28 | 40–60 |
| Radicchio | Mar 8 | Mar 29 | Apr 12 | Jun 14 – Jul 19 | 60–80 |
| Radish | — | Mar 29 | — | Apr 26 – May 17 | 22–35 |
| Rhubarb | — | — | May 3 | — | 365–730 |
| Romanesco | Mar 8 | Mar 29 | Apr 12 | Jun 28 – Aug 9 | 75–100 |
| Rutabaga | — | Mar 29 | — | Jun 21 – Jul 26 | 80–100 |
| Salsify | — | Mar 29 | — | Jul 12 – Aug 23 | 100–130 |
| Savoy Cabbage | Mar 8 | Mar 29 | Apr 12 | Jun 21 – Aug 16 | 70–110 |
| Scallions | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Jul 5 | 50–70 |
| Scarlet Runner Beans | Feb 22 | Apr 19 | Apr 26 | Jun 28 – Aug 2 | 60–80 |
| Shallot | Mar 8 | Mar 29 | Apr 12 | Jul 12 – Aug 30 | 90–120 |
| Shiso | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 16 | 50–70 |
| Snap Peas | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 16 | 55–70 |
| Snow Peas | Mar 8 | Mar 29 | Apr 12 | Jun 7 – Aug 2 | 50–65 |
| Soybeans | — | Apr 19 | — | Jul 12 – Sep 6 | 80–120 |
| Spaghetti Squash | Mar 15 | Apr 19 | Apr 26 | Jul 26 – Aug 23 | 85–100 |
| Spinach | Mar 8 | Mar 29 | Apr 12 | May 17 – Jul 19 | 35–50 |
| Squash (Summer) | Mar 15 | Apr 19 | Apr 26 | Jun 14 – Aug 16 | 45–65 |
| Squash (Winter) | Mar 15 | Apr 19 | Apr 26 | Jul 19 – Sep 13 | 80–120 |
| Sunchoke | — | — | Apr 26 | Aug 16 – Oct 11 | 110–150 |
| Sunflower | Feb 22 | Apr 19 | Apr 26 | Jul 5 – Aug 23 | 70–100 |
| Sweet Corn | — | Apr 19 | — | Jun 21 – Aug 2 | 60–90 |
| Sweet Potatoes | Feb 22 | Apr 19 | Apr 26 | Jul 26 – Sep 13 | 90–120 |
| Tatsoi | Mar 8 | Mar 29 | Apr 12 | May 17 – Jun 21 | 35–50 |
| Tomatillo | Feb 22 | Apr 19 | Apr 26 | Jun 28 – Sep 6 | 60–85 |
| Tomatoes | Feb 22 | Apr 19 | Apr 26 | Jun 28 – Sep 6 | 60–85 |
| Turnip | — | Mar 29 | — | May 10 – Jun 14 | 40–60 |
| Watercress | Mar 8 | Mar 29 | Apr 12 | May 24 – Jun 28 | 40–60 |
| Watermelon | Mar 15 | Apr 19 | Apr 26 | Jul 5 – Aug 23 | 70–100 |
| Wax Beans | — | Apr 19 | — | Jun 14 – Aug 9 | 50–65 |
| Winter Melon | Feb 22 | Apr 19 | Apr 26 | Jul 26 – Sep 13 | 90–120 |
| Yard Long Beans | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 2 | 55–80 |
| Zucchini | Mar 15 | Apr 19 | Apr 26 | Jun 14 – Aug 9 | 45–60 |
🍓 Fruits to Grow in Mercer County
31 fruits that grow well in Zone 7a with planting dates for Mercer County.
Show all 31 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | May 3 | Aug 2 – Nov 15 | 90–180 |
| Aronia | — | — | May 3 | — | 730–1095 |
| Blackberries | — | — | May 3 | — | 365–730 |
| Blueberries | — | — | May 3 | — | 730–1095 |
| Boysenberries | — | — | May 3 | — | 365–730 |
| Cantaloupe | — | — | May 3 | Jul 12 – Aug 16 | 70–90 |
| Che Fruit | — | — | May 3 | — | 1095–1825 |
| Cranberries | — | — | May 3 | — | 730–1095 |
| Currants | — | — | May 3 | — | 730–1095 |
| Elderberries | — | — | May 3 | — | 730–1095 |
| Figs | — | — | May 3 | — | 730–1825 |
| Goji Berries | — | — | May 3 | — | 730–1095 |
| Gooseberries | — | — | May 3 | — | 730–1095 |
| Grapes | — | — | May 3 | — | 730–1095 |
| Ground Cherry | — | — | May 3 | Jul 12 – Sep 6 | 65–80 |
| Hardy Kiwi | — | — | May 3 | — | 1095–1825 |
| Haskaps | — | — | May 3 | — | 730–1095 |
| Honeydew | — | — | May 3 | Jul 26 – Sep 6 | 80–110 |
| Jostaberry | — | — | May 3 | — | 730–1095 |
| Kiwi | — | — | May 3 | — | 1095–1825 |
| Lingonberries | — | — | May 3 | — | 730–1095 |
| Loquat | — | — | May 3 | — | 730–1825 |
| Medlar | — | — | May 3 | — | 1095–1825 |
| Mulberries | — | — | May 3 | — | 730–1825 |
| Pawpaw | — | — | May 3 | — | 1095–2555 |
| Persimmon | — | — | May 3 | — | 1095–2555 |
| Pomegranate | — | — | May 3 | — | 730–1095 |
| Quince | — | — | May 3 | — | 1095–1825 |
| Raspberries | — | — | May 3 | — | 365–730 |
| Serviceberries | — | — | May 3 | — | 730–1095 |
| Strawberries | — | — | May 3 | Aug 2 – Dec 13 | 90–365 |
🌿 Herbs to Grow in Mercer County
39 herbs that grow well in Zone 7a with planting dates for Mercer County.
Show all 39 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Mar 8 | Mar 29 | Apr 5 | — | 365–730 |
| Anise | Mar 8 | Mar 29 | Apr 5 | Jul 5 – Sep 20 | 90–120 |
| Basil | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 23 | 50–75 |
| Bee Balm | — | — | Apr 19 | Jul 19 – Oct 4 | 90–120 |
| Borage | Mar 8 | Mar 29 | Apr 5 | May 31 – Jul 19 | 50–60 |
| Caraway | Mar 8 | Mar 29 | Apr 5 | — | 365–450 |
| Catnip | — | — | Apr 19 | Jun 21 – Aug 23 | 60–80 |
| Chamomile | Mar 8 | Mar 29 | Apr 5 | Jun 7 – Aug 16 | 60–90 |
| Chervil | Mar 8 | Mar 29 | Apr 5 | May 17 – Jul 19 | 40–60 |
| Chives | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Cilantro | Mar 8 | Mar 29 | Apr 5 | May 17 – Jul 19 | 40–60 |
| Comfrey | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Cumin | Mar 8 | Mar 29 | Apr 5 | Jul 19 – Sep 20 | 100–120 |
| Dill | Mar 8 | Mar 29 | Apr 5 | May 17 – Jul 19 | 40–60 |
| Echinacea | — | — | Apr 19 | Aug 23 – Nov 29 | 120–180 |
| Epazote | Feb 22 | Apr 19 | Apr 26 | Jun 14 – Aug 9 | 45–60 |
| Fennel (herb) | Mar 8 | Mar 29 | Apr 5 | Jun 7 – Aug 16 | 60–90 |
| Feverfew | — | — | Apr 19 | Jul 19 – Oct 4 | 90–120 |
| Garlic Chives | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Horehound | — | — | Apr 19 | Jul 5 – Aug 30 | 75–90 |
| Hyssop | — | — | Apr 19 | Jun 28 – Aug 30 | 70–90 |
| Lavender | — | — | Apr 19 | Jul 19 – Nov 29 | 90–200 |
| Lemon Balm | — | — | Apr 19 | Jun 21 – Aug 9 | 60–70 |
| Lemon Thyme | — | — | Apr 19 | Jun 28 – Aug 30 | 70–90 |
| Lovage | — | — | Apr 19 | Jun 28 – Aug 30 | 70–90 |
| Marjoram | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Mint | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Oregano | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Parsley | Mar 8 | Mar 29 | Apr 5 | Jun 7 – Aug 9 | 60–80 |
| Rosemary | — | — | Apr 19 | Jul 12 – Nov 29 | 80–180 |
| Rue | — | — | Apr 19 | Jun 28 – Aug 30 | 70–90 |
| Sage | — | — | Apr 19 | Jul 5 – Aug 30 | 75–90 |
| Savory | — | — | Apr 19 | Jun 14 – Aug 9 | 50–70 |
| Sorrel | Mar 8 | Mar 29 | Apr 5 | May 17 – Jul 19 | 40–60 |
| Tarragon | — | — | Apr 19 | Jun 21 – Aug 30 | 60–90 |
| Thai Basil | Feb 22 | Apr 19 | Apr 26 | Jun 21 – Aug 23 | 50–75 |
| Thyme | — | — | Apr 19 | Jun 28 – Aug 30 | 70–90 |
| Valerian | — | — | Apr 19 | Aug 23 – Nov 29 | 120–180 |
| Yarrow | — | — | Apr 19 | Jul 19 – Oct 4 | 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, NJ?
Mercer County is in USDA Hardiness Zone 7a. 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, NJ?
Based on 31 years of NOAA weather station data, the median last spring frost in Mercer County falls around April 12. In 8 out of 10 years, last frost lands between March 26 and May 1 — a 35-day window of variability. Use May 1 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Mercer County, NJ?
The median first fall frost in Mercer County arrives around October 29. In cold years it can arrive as early as October 10; in mild years as late as November 12. 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 200 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 0.79 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 5–6.7 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. 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 75/100 (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.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Mercer County gardeners in Zone 7a 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.
