Jefferson County, WI — Planting Guide
Jefferson County is in USDA Zone 5a. The average last spring frost is April 27 and the first fall frost is October 12, giving you a growing season of approximately 168 days.
At an elevation of 613 ft, Jefferson County receives approximately 36.9 in of rainfall annually. Summer highs average 87°F with winter lows around 20°F. The predominant soil type is Silt Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 25 days year to year — ranging from April 18 in warm years to May 13 in cold years. The growing season is trending longer by about 0.5 days per decade. Jefferson County scores 75/100 (Good) on the Microclimate Index.
🌡️ Zone
5a (-20°F to -15°F min)
❄️ Last Frost
April 27
🍂 First Frost
October 12
📅 Growing Season
168 days
⛰️ Elevation
613 ft
🌧️ Annual Rainfall
36.9 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 | 1.7 in | 6 days | — | None |
| Feb | 1.6 in | 6 days | — | None |
| Mar | 2.4 in | 8 days | — | None |
| Apr | 2.9 in | 9 days | 1.4 in | Moderate |
| May | 4.6 in | 11 days | — | Low |
| Jun | 4.4 in | 8 days | — | Low |
| Jul | 3.9 in | 7 days | 0.4 in | Low |
| Aug | 4.2 in | 9 days | 0.1 in | Low |
| Sep | 3.6 in | 7 days | 0.7 in | Moderate |
| Oct | 2.7 in | 7 days | 1.6 in | High |
| Nov | 2.7 in | 9 days | — | None |
| Dec | 2.2 in | 8 days | — | None |
Annual total: 36.9 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.
Jefferson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.7
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 13 | Oct 26 | 166 days |
| Cautious | May 3 | Oct 16 | 166 days |
| Average year | Apr 27 | Oct 12 | 168 days |
| Optimistic | Apr 23 | Oct 7 | 167 days |
| Aggressive (risky) | Apr 18 | Oct 3 | 168 days |
Not very — frost dates can vary by ±25 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 (0.5 days/decade). Historical frost dates are still reliable for planning.
Gardening Difficulty Score
Jefferson County offers good growing conditions. A little planning around frost dates goes a long way.
Local Gardening Help in Jefferson 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 Jefferson County's climate and soil.
County Extension Office
Jefferson County University of Wisconsin-Madison Division of Extension Extension Office
Phone: 608-263-7779
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 Jefferson County
Finding local nurseries & garden centers in Jefferson County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Jefferson 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 Jefferson County WI" or "garden center Jefferson 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 Jefferson County WI" or check your extension office and local parks department. Facebook groups like "Jefferson County Gardeners" or "Wisconsin 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
15.2 hours
Summer solstice daylight
Shortest Day
8.8 hours
Winter solstice daylight
Peak Sun Hours
9.2 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 | 9.2 hr | 3.8 hr | Short day |
| February | 10.3 hr | 4.3 hr | Short day |
| March | 11.6 hr | 5.7 hr | Short day |
| April | 13.2 hr | 6.7 hr | Neutral |
| May | 14.5 hr | 8.4 hr | Long day |
| June | 15.2 hr | 9.2 hr | Long day |
| July | 14.9 hr | 9.2 hr | Long day |
| August | 13.8 hr | 8.5 hr | Neutral |
| September | 12.3 hr | 7.4 hr | Neutral |
| October | 10.8 hr | 5.7 hr | Short day |
| November | 9.5 hr | 3.8 hr | Short day |
| December | 8.8 hr | 3.2 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
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 | 25°F | 30°F | ❄️ Dormant | ~36 weeks |
| Feb | 24°F | 29°F | ❄️ Dormant | ~36 weeks |
| Mar | 32°F | 34°F | ❄️ Dormant | ~36 weeks |
| Apr | 43°F | 44°F | 🐢 Slow | ~24 weeks |
| May | 60°F | 55°F | ♻️ Active | ~14 weeks |
| Jun | 69°F | 63°F | 🔥 Peak | ~8 weeks |
| Jul | 77°F | 69°F | 🔥 Peak | ~8 weeks |
| Aug | 80°F | 73°F | 🔥 Peak | ~8 weeks |
| Sep | 72°F | 69°F | 🔥 Peak | ~8 weeks |
| Oct | 57°F | 59°F | ♻️ Active | ~14 weeks |
| Nov | 44°F | 50°F | 🐢 Slow | ~24 weeks |
| Dec | 32°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 Jefferson 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 | Low | 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 Jefferson 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 1 | Aug 17 | — | Rapid growth, attracts pollinators, suppresses weeds |
| Sorghum-sudan grass | May 1 | Aug 3 | — | Massive biomass, breaks compaction, suppresses nematodes |
| White clover | Mar 30 | Aug 17 | ✓ 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 18 | Sep 14 | — | 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 16 | Apr 13 | ✓ Yes | Fixes nitrogen, good for heavy clay soils |
| Daikon radish | Aug 22 | Apr 13 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jul 29 | Apr 13 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Sep 2 | Apr 6 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jul 21 | Apr 6 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jul 13 | Apr 6 | — | 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: 13 mph Summer: 8 mph
Fall: 11 mph Winter: 11 mph
Prevailing wind: SW. Moderate wind — consider a temporary windbreak for young seedlings.
Windbreak Benefit
5/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
Low
Relatively flat terrain (134 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
18,390 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
6 rain barrels (55 gal each)
For a typical 500 sq ft garden. Serious collectors: consider a 1,500 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
May, Jun, Jul, Aug
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 36.9 inches of rain per year
- A 1,000 sq ft roof can collect roughly 18,390 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 Jefferson County
Soil Type
Silt Loam
Soil pH 6.3–6.7 · Excessively 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. (36.9 in. annual rainfall)
Season Tips
168-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 Jefferson County
106 vegetables that grow well in Zone 5a with planting dates for Jefferson County.
Show all 106 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Mar 23 | May 4 | May 11 | Aug 3 – Sep 7 | 80–100 |
| Amaranth | Mar 2 | May 4 | May 11 | Aug 10 – Sep 28 | 90–120 |
| Arugula | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Aug 3 | 30–50 |
| Asparagus | — | — | May 11 | — | 730–1095 |
| Beets | — | Apr 13 | — | Jun 8 – Jul 6 | 50–70 |
| Belgian Endive | Mar 23 | Apr 13 | Apr 27 | Aug 17 – Oct 12 | 110–150 |
| Bitter Melon | Mar 2 | May 4 | May 11 | Jul 13 – Aug 24 | 60–90 |
| Black Beans | — | May 4 | — | Aug 3 – Sep 21 | 90–120 |
| Bok Choy | Mar 23 | Apr 13 | Apr 27 | Jun 8 – Jul 13 | 40–60 |
| Broccoli | Mar 23 | Apr 13 | Apr 27 | Jun 29 – Aug 10 | 60–90 |
| Broccoli Rabe | Mar 23 | Apr 13 | Apr 27 | Jun 8 – Jul 13 | 40–60 |
| Brussels Sprouts | Mar 23 | Apr 13 | Apr 27 | Jul 27 – Sep 21 | 90–130 |
| Butternut Squash | Mar 23 | May 4 | May 11 | Aug 10 – Sep 14 | 85–110 |
| Cabbage | Mar 23 | Apr 13 | Apr 27 | Jun 29 – Aug 24 | 60–100 |
| Calabash | Mar 2 | May 4 | May 11 | Aug 3 – Sep 28 | 80–120 |
| Carrots | — | Apr 13 | — | Jun 15 – Jul 20 | 60–80 |
| Cauliflower | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Aug 24 | 55–100 |
| Celeriac | Mar 23 | Apr 13 | Apr 27 | Aug 10 – Sep 14 | 100–120 |
| Celery | Mar 23 | Apr 13 | Apr 27 | Jul 20 – Sep 14 | 80–120 |
| Celtuce | Mar 23 | Apr 13 | Apr 27 | Jun 29 – Aug 10 | 60–90 |
| Chard | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Aug 10 | 50–60 |
| Chickpeas | Mar 23 | Apr 13 | Apr 27 | Jul 20 – Aug 31 | 80–110 |
| Chicory | Mar 23 | Apr 13 | Apr 27 | Jun 29 – Aug 10 | 60–85 |
| Chinese Cabbage | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Jul 20 | 50–70 |
| Christmas Lima Beans | Mar 2 | May 4 | May 11 | Aug 3 – Sep 7 | 80–100 |
| Collard Greens | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Aug 24 | 55–75 |
| Corn | — | May 4 | — | Jul 6 – Aug 31 | 60–100 |
| Cowpeas | — | May 4 | — | Jul 6 – Aug 17 | 60–90 |
| Cress | Mar 23 | Apr 13 | Apr 27 | May 11 – Jun 1 | 14–21 |
| Crookneck Squash | Mar 23 | May 4 | May 11 | Jun 29 – Jul 27 | 45–60 |
| Crosne | — | Apr 13 | — | Sep 14 – Sep 28 | 150–200 |
| Cucumber | Mar 23 | May 4 | May 11 | Jul 6 – Aug 31 | 50–70 |
| Daikon | — | Apr 13 | — | Jun 8 – Jul 6 | 50–70 |
| Delicata Squash | Mar 23 | May 4 | May 11 | Aug 3 – Sep 7 | 80–100 |
| Edamame | — | May 4 | — | Jul 20 – Aug 31 | 75–100 |
| Eggplant | Feb 16 | May 4 | May 11 | Jul 20 – Sep 21 | 65–85 |
| Endive | Mar 23 | Apr 13 | Apr 27 | Jun 15 – Jul 20 | 45–65 |
| Escarole | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Jul 20 | 50–70 |
| Fava Beans | Mar 23 | Apr 13 | Apr 27 | Jul 13 – Aug 24 | 75–100 |
| Fennel | Mar 2 | May 4 | May 11 | Jul 13 – Aug 24 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | May 4 | — | Jun 29 – Aug 24 | 50–65 |
| Horseradish | — | — | May 11 | Sep 14 – Oct 26 | 120–180 |
| Hot Peppers | Feb 16 | May 4 | May 11 | Jul 20 – Oct 26 | 70–120 |
| Hubbard Squash | Mar 23 | May 4 | May 11 | Aug 24 – Sep 28 | 100–120 |
| Kabocha | Mar 23 | May 4 | May 11 | Aug 10 – Sep 7 | 85–100 |
| Kai Lan | Mar 23 | Apr 13 | Apr 27 | Jun 15 – Jul 13 | 45–60 |
| Kale | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Aug 17 | 50–70 |
| Kidney Beans | — | May 4 | — | Aug 3 – Sep 7 | 85–110 |
| Kohlrabi | Mar 23 | Apr 13 | Apr 27 | Jun 15 – Jul 20 | 45–65 |
| Komatsuna | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Jul 6 | 35–50 |
| Leeks | Mar 23 | Apr 13 | Apr 27 | Jul 27 – Oct 12 | 90–150 |
| Lentils | Mar 23 | Apr 13 | Apr 27 | Jul 20 – Aug 31 | 80–110 |
| Lettuce | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Aug 10 | 30–60 |
| Lima Beans | — | May 4 | — | Jul 6 – Aug 17 | 60–90 |
| Mache | Mar 23 | Apr 13 | Apr 27 | Jun 8 – Jul 13 | 40–60 |
| Melon | Mar 23 | May 4 | May 11 | Jul 20 – Sep 7 | 70–100 |
| Microgreens | Mar 23 | Apr 13 | Apr 27 | May 4 – Jun 1 | 7–21 |
| Mitsuba | Mar 23 | Apr 13 | Apr 20 | Jun 15 – Aug 10 | 50–70 |
| Mizuna | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Jun 29 | 30–45 |
| Mustard Greens | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Aug 3 | 30–50 |
| Napa Cabbage | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Jul 27 | 55–75 |
| New Zealand Spinach | Mar 2 | May 4 | May 11 | Jul 6 – Aug 3 | 55–70 |
| Okra | Mar 2 | May 4 | May 11 | Jul 6 – Aug 31 | 50–65 |
| Onion | Mar 23 | Apr 13 | Apr 27 | Jul 27 – Sep 14 | 90–120 |
| Pac Choi | Mar 23 | Apr 13 | Apr 27 | Jun 8 – Jul 6 | 40–55 |
| Parsnip | — | Apr 13 | — | Jul 27 – Sep 7 | 100–130 |
| Patty Pan Squash | Mar 23 | May 4 | May 11 | Jun 29 – Jul 27 | 45–60 |
| Peas | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Aug 17 | 55–70 |
| Peppers | Feb 16 | May 4 | May 11 | Jul 13 – Sep 21 | 60–90 |
| Pole Beans | Mar 2 | May 4 | May 11 | Jul 6 – Aug 31 | 55–70 |
| Potatoes | Mar 2 | May 4 | May 11 | Jul 20 – Sep 28 | 70–120 |
| Pumpkin | Mar 23 | May 4 | May 11 | Aug 10 – Sep 28 | 85–120 |
| Purslane | Mar 23 | Apr 13 | Apr 27 | Jun 8 – Jul 13 | 40–60 |
| Radicchio | Mar 23 | Apr 13 | Apr 27 | Jun 29 – Aug 3 | 60–80 |
| Radish | — | Apr 13 | — | May 11 – Jun 1 | 22–35 |
| Rhubarb | — | — | May 18 | — | 365–730 |
| Romanesco | Mar 23 | Apr 13 | Apr 27 | Jul 13 – Aug 24 | 75–100 |
| Rutabaga | — | Apr 13 | — | Jul 6 – Aug 10 | 80–100 |
| Salsify | — | Apr 13 | — | Jul 27 – Sep 7 | 100–130 |
| Savoy Cabbage | Mar 23 | Apr 13 | Apr 27 | Jul 6 – Aug 31 | 70–110 |
| Scallions | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Jul 20 | 50–70 |
| Scarlet Runner Beans | Mar 2 | May 4 | May 11 | Jul 13 – Aug 17 | 60–80 |
| Shallot | Mar 23 | Apr 13 | Apr 27 | Jul 27 – Sep 14 | 90–120 |
| Shiso | Mar 9 | May 4 | May 11 | Jul 6 – Aug 31 | 50–70 |
| Snap Peas | Mar 2 | May 4 | May 11 | Jul 6 – Aug 31 | 55–70 |
| Snow Peas | Mar 23 | Apr 13 | Apr 27 | Jun 22 – Aug 17 | 50–65 |
| Soybeans | — | May 4 | — | Jul 27 – Sep 21 | 80–120 |
| Spaghetti Squash | Mar 23 | May 4 | May 11 | Aug 10 – Sep 7 | 85–100 |
| Spinach | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Aug 3 | 35–50 |
| Squash (Summer) | Mar 23 | May 4 | May 11 | Jun 29 – Aug 31 | 45–65 |
| Squash (Winter) | Mar 23 | May 4 | May 11 | Aug 3 – Sep 28 | 80–120 |
| Sunchoke | — | — | May 11 | Aug 31 – Oct 26 | 110–150 |
| Sunflower | Mar 2 | May 4 | May 11 | Jul 20 – Sep 7 | 70–100 |
| Sweet Corn | — | May 4 | — | Jul 6 – Aug 17 | 60–90 |
| Sweet Potatoes | Mar 2 | May 4 | May 11 | Aug 10 – Sep 28 | 90–120 |
| Tatsoi | Mar 23 | Apr 13 | Apr 27 | Jun 1 – Jul 6 | 35–50 |
| Tomatillo | Mar 2 | May 4 | May 11 | Jul 13 – Sep 21 | 60–85 |
| Tomatoes | Mar 2 | May 4 | May 11 | Jul 13 – Sep 21 | 60–85 |
| Turnip | — | Apr 13 | — | May 25 – Jun 29 | 40–60 |
| Watercress | Mar 23 | Apr 13 | Apr 27 | Jun 8 – Jul 13 | 40–60 |
| Watermelon | Mar 23 | May 4 | May 11 | Jul 20 – Sep 7 | 70–100 |
| Wax Beans | — | May 4 | — | Jun 29 – Aug 24 | 50–65 |
| Winter Melon | Mar 2 | May 4 | May 11 | Aug 10 – Sep 28 | 90–120 |
| Yard Long Beans | Mar 2 | May 4 | May 11 | Jul 6 – Aug 17 | 55–80 |
| Zucchini | Mar 23 | May 4 | May 11 | Jun 29 – Aug 24 | 45–60 |
🍓 Fruits to Grow in Jefferson County
27 fruits that grow well in Zone 5a with planting dates for Jefferson County.
Show all 27 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | May 18 | Aug 17 – Nov 2 | 90–180 |
| Aronia | — | — | May 18 | — | 730–1095 |
| Blackberries | — | — | May 18 | — | 365–730 |
| Blueberries | — | — | May 18 | — | 730–1095 |
| Boysenberries | — | — | May 18 | — | 365–730 |
| Cantaloupe | — | — | May 18 | Jul 27 – Aug 31 | 70–90 |
| Che Fruit | — | — | May 18 | — | 1095–1825 |
| Cranberries | — | — | May 18 | — | 730–1095 |
| Currants | — | — | May 18 | — | 730–1095 |
| Elderberries | — | — | May 18 | — | 730–1095 |
| Goji Berries | — | — | May 18 | — | 730–1095 |
| Gooseberries | — | — | May 18 | — | 730–1095 |
| Grapes | — | — | May 18 | — | 730–1095 |
| Ground Cherry | — | — | May 18 | Jul 27 – Sep 21 | 65–80 |
| Hardy Kiwi | — | — | May 18 | — | 1095–1825 |
| Haskaps | — | — | May 18 | — | 730–1095 |
| Honeydew | — | — | May 18 | Aug 10 – Sep 21 | 80–110 |
| Jostaberry | — | — | May 18 | — | 730–1095 |
| Lingonberries | — | — | May 18 | — | 730–1095 |
| Medlar | — | — | May 18 | — | 1095–1825 |
| Mulberries | — | — | May 18 | — | 730–1825 |
| Pawpaw | — | — | May 18 | — | 1095–2555 |
| Persimmon | — | — | May 18 | — | 1095–2555 |
| Quince | — | — | May 18 | — | 1095–1825 |
| Raspberries | — | — | May 18 | — | 365–730 |
| Serviceberries | — | — | May 18 | — | 730–1095 |
| Strawberries | — | — | May 18 | Aug 17 – Nov 2 | 90–365 |
🌿 Herbs to Grow in Jefferson County
37 herbs that grow well in Zone 5a with planting dates for Jefferson County.
Show all 37 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Mar 23 | Apr 13 | Apr 20 | — | 365–730 |
| Anise | Mar 23 | Apr 13 | Apr 20 | Jul 20 – Oct 5 | 90–120 |
| Basil | Mar 9 | May 4 | May 11 | Jul 6 – Sep 7 | 50–75 |
| Bee Balm | — | — | May 4 | Aug 3 – Oct 19 | 90–120 |
| Borage | Mar 23 | Apr 13 | Apr 20 | Jun 15 – Aug 3 | 50–60 |
| Caraway | Mar 23 | Apr 13 | Apr 20 | — | 365–450 |
| Catnip | — | — | May 4 | Jul 6 – Sep 7 | 60–80 |
| Chamomile | Mar 23 | Apr 13 | Apr 20 | Jun 22 – Aug 31 | 60–90 |
| Chervil | Mar 23 | Apr 13 | Apr 20 | Jun 1 – Aug 3 | 40–60 |
| Chives | — | — | May 4 | Jul 6 – Sep 14 | 60–90 |
| Cilantro | Mar 23 | Apr 13 | Apr 20 | Jun 1 – Aug 3 | 40–60 |
| Comfrey | — | — | May 4 | Jul 6 – Sep 14 | 60–90 |
| Cumin | Mar 23 | Apr 13 | Apr 20 | Aug 3 – Oct 5 | 100–120 |
| Dill | Mar 23 | Apr 13 | Apr 20 | Jun 1 – Aug 3 | 40–60 |
| Echinacea | — | — | May 4 | Sep 7 – Oct 19 | 120–180 |
| Epazote | Mar 9 | May 4 | May 11 | Jun 29 – Aug 24 | 45–60 |
| Fennel (herb) | Mar 23 | Apr 13 | Apr 20 | Jun 22 – Aug 31 | 60–90 |
| Feverfew | — | — | May 4 | Aug 3 – Oct 19 | 90–120 |
| Garlic Chives | — | — | May 4 | Jul 6 – Sep 14 | 60–90 |
| Horehound | — | — | May 4 | Jul 20 – Sep 14 | 75–90 |
| Hyssop | — | — | May 4 | Jul 13 – Sep 14 | 70–90 |
| Lavender | — | — | May 4 | Aug 3 – Oct 19 | 90–200 |
| Lemon Balm | — | — | May 4 | Jul 6 – Aug 24 | 60–70 |
| Lemon Thyme | — | — | May 4 | Jul 13 – Sep 14 | 70–90 |
| Lovage | — | — | May 4 | Jul 13 – Sep 14 | 70–90 |
| Mint | — | — | May 4 | Jul 6 – Sep 14 | 60–90 |
| Oregano | — | — | May 4 | Jul 6 – Sep 14 | 60–90 |
| Parsley | Mar 23 | Apr 13 | Apr 20 | Jun 22 – Aug 24 | 60–80 |
| Rue | — | — | May 4 | Jul 13 – Sep 14 | 70–90 |
| Sage | — | — | May 4 | Jul 20 – Sep 14 | 75–90 |
| Savory | — | — | May 4 | Jun 29 – Aug 24 | 50–70 |
| Sorrel | Mar 23 | Apr 13 | Apr 20 | Jun 1 – Aug 3 | 40–60 |
| Tarragon | — | — | May 4 | Jul 6 – Sep 14 | 60–90 |
| Thai Basil | Mar 9 | May 4 | May 11 | Jul 6 – Sep 7 | 50–75 |
| Thyme | — | — | May 4 | Jul 13 – Sep 14 | 70–90 |
| Valerian | — | — | May 4 | Sep 7 – Oct 19 | 120–180 |
| Yarrow | — | — | May 4 | Aug 3 – Oct 19 | 90–120 |
Monthly Planting Guide for Jefferson County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Jefferson County.
Frequently Asked Questions
What planting zone is Jefferson County, WI?
Jefferson County is in USDA Hardiness Zone 5a. 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 Jefferson County, WI?
Based on 31 years of NOAA weather station data, the median last spring frost in Jefferson County falls around April 27. In 8 out of 10 years, last frost lands between April 18 and May 13 — a 25-day window of variability. Use May 13 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Jefferson County, WI?
The median first fall frost in Jefferson County arrives around October 12. In cold years it can arrive as early as October 3; in mild years as late as October 26. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Jefferson County?
Jefferson County has a frost-free growing season of approximately 168 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 0.5 days per decade.
What is the soil like in Jefferson County for gardening?
Jefferson County has predominantly Silt Loam soil with a pH range of 6.3–6.7 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Jefferson County?
Jefferson County has commercial agriculture that includes Corn, Soybeans, Hay. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Jefferson County a good location for home gardening?
Jefferson 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 Jefferson County gardeners in Zone 5a 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.
