Johnson County, WY — Planting Guide
Johnson County is in USDA Zone 4a. The average last spring frost is May 17 and the first fall frost is September 21, giving you a growing season of approximately 127 days.
At an elevation of 8,281 ft, Johnson County receives approximately 23.7 in of rainfall annually. Summer highs average 81°F with winter lows around 3°F. The predominant soil type is Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 32 days year to year — ranging from May 5 in warm years to June 7 in cold years. The growing season is trending longer by about 1.95 days per decade. Johnson County scores 39/100 (Challenging) on the Microclimate Index.
🌡️ Zone
4a (-30°F to -25°F min)
❄️ Last Frost
May 17
🍂 First Frost
September 21
📅 Growing Season
127 days
⛰️ Elevation
8,281 ft
🌧️ Annual Rainfall
23.7 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 | 1.8 in | 6 days | — | None |
| Feb | 1.5 in | 5 days | — | None |
| Mar | 1.9 in | 7 days | — | None |
| Apr | 2.1 in | 7 days | 2.2 in | High |
| May | 2.8 in | 7 days | 1.5 in | Moderate |
| Jun | 1.6 in | 5 days | 2.7 in | High |
| Jul | 2.3 in | 6 days | 2 in | High |
| Aug | 2.5 in | 7 days | 1.8 in | High |
| Sep | 2.1 in | 5 days | 2.2 in | High |
| Oct | 2.1 in | 6 days | 2.2 in | High |
| Nov | 1.5 in | 6 days | — | None |
| Dec | 1.5 in | 7 days | — | None |
Annual total: 23.7 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.
Johnson County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.8
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) | Jun 7 | Oct 7 | 122 days |
| Cautious | May 23 | Sep 26 | 126 days |
| Average year | May 17 | Sep 21 | 127 days |
| Optimistic | May 13 | Sep 14 | 124 days |
| Aggressive (risky) | May 5 | Sep 6 | 124 days |
Not very — frost dates can vary by ±32 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 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Johnson County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Johnson 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 Johnson County's climate and soil.
County Extension Office
Johnson County University of Wyoming Extension Extension Office
Phone: 307-766-5124
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 Johnson County
Finding local nurseries & garden centers in Johnson County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Johnson 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 Johnson County WY" or "garden center Johnson 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 Johnson County WY" or check your extension office and local parks department. Facebook groups like "Johnson County Gardeners" or "Wyoming 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.
Sunlight & Day Length
Monthly daylight hours and peak sun — critical for onion varieties, photoperiod-sensitive plants, and solar garden planning.
Longest Day
15.3 hours
Summer solstice daylight
Shortest Day
8.7 hours
Winter solstice daylight
Peak Sun Hours
10.8 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 | 9.1 hr | 5.2 hr | Short day |
| February | 10.2 hr | 5.8 hr | Short day |
| March | 11.6 hr | 7.2 hr | Short day |
| April | 13.2 hr | 7.3 hr | Neutral |
| May | 14.6 hr | 8.9 hr | Long day |
| June | 15.3 hr | 10.8 hr | Long day |
| July | 15 hr | 10 hr | Long day |
| August | 13.8 hr | 9.3 hr | Neutral |
| September | 12.3 hr | 8.7 hr | Neutral |
| October | 10.7 hr | 6.8 hr | Short day |
| November | 9.4 hr | 5.4 hr | Short day |
| December | 8.7 hr | 4.9 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 rarely reaches 60°F — use black plastic mulch to warm soil.
Best Month to Compost
Apr
Microbial activity peaks when soil is warm.
Active Composting
0 months
Short season — insulate pile or use indoor vermicomposting.
View detailed monthly data
| Month | Soil 4" Deep | Soil 8" Deep | Compost Activity | Time to Finish |
|---|---|---|---|---|
| Jan | -9°F | -3°F | ❄️ Dormant | ~36 weeks |
| Feb | -8°F | -4°F | ❄️ Dormant | ~36 weeks |
| Mar | -0°F | 3°F | ❄️ Dormant | ~36 weeks |
| Apr | 14°F | 14°F | ❄️ Dormant | ~36 weeks |
| May | 30°F | 24°F | ❄️ Dormant | ~36 weeks |
| Jun | 39°F | 35°F | ❄️ Dormant | ~36 weeks |
| Jul | 49°F | 41°F | 🐢 Slow | ~24 weeks |
| Aug | 49°F | 44°F | 🐢 Slow | ~24 weeks |
| Sep | 42°F | 38°F | 🐢 Slow | ~24 weeks |
| Oct | 27°F | 31°F | ❄️ Dormant | ~36 weeks |
| Nov | 11°F | 18°F | ❄️ Dormant | ~36 weeks |
| Dec | -2°F | 7°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 Johnson 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 5 common pests in your area
| Pest | Risk Level | Peak Months |
|---|---|---|
| Aphids | Moderate | May, Jun, Jul, Aug |
| Cabbage worms | Low | Jun, Jul, Aug |
| Colorado potato beetle | Low | Jun, Jul |
| Flea beetles | Low | May, Jun, Jul |
| Slugs | Low | May, Jun, Jul, Aug, Sep |
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 Johnson County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Spring Cover Crops (2 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | May 28 | Jul 13 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | Apr 17 | Jul 27 | ✓ 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 | Jun 16 | Aug 24 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Fall Cover Crops (5 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Daikon radish | Jul 31 | Apr 26 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jul 9 | May 3 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 7 | Apr 26 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 25 | May 3 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 25 | Apr 26 | — | 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: 16 mph Summer: 11 mph
Fall: 13 mph Winter: 14 mph
Prevailing wind: W. Windy area — plant a windbreak hedge on the W side of your garden.
Windbreak Benefit
6.8/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
High
Hilly terrain with 1,376 ft of elevation range — cold air pools in low spots. Avoid planting frost-sensitive crops in valleys.
Rainwater Harvesting Potential
How much water you can collect, when to collect it, and what size system you need for your garden.
Annual Collection
11,812 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 1,750 gal tank.
Legal Status
Unrestricted
Rainwater harvesting is fully legal in your state with no restrictions.
Best Collection Months
Apr, May, Jul, Aug
Highest rainfall months — your barrels will fill up quickly during these months.
Months to Draw From Storage
Feb, Nov, 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 23.7 inches of rain per year
- A 1,000 sq ft roof can collect roughly 11,812 gallons annually
- Rainwater harvesting is fully legal in your state
- Stock up on stored water before your dry season (Feb, Nov, Dec)
- Use a first-flush diverter to keep roof debris out of your collection
Soil & Growing Conditions in Johnson County
Soil Type
Loam
Soil pH 6.8–7.8 · Excessively Drained drainage
Good candidate for raised beds to maximise drainage and extend the season.
Watering Needs
Drought stress: 5.5/10
Moderate drought pressure. Drip irrigation and mulching are highly recommended to maintain soil moisture through summer.
Season Tips
127-day frost-free season
A short season means indoor starts are critical for warm-season crops. Prioritise cold-hardy, fast-maturing varieties and use row covers to extend autumn harvests.
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 Johnson County
96 vegetables that grow well in Zone 4a with planting dates for Johnson County.
Show all 96 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 5 | May 31 | Jun 7 | Aug 30 – Oct 4 | 80–100 |
| Amaranth | Mar 15 | May 31 | Jun 7 | Sep 6 – Oct 25 | 90–120 |
| Arugula | Apr 5 | May 10 | May 17 | Jun 21 – Aug 23 | 30–50 |
| Asparagus | — | — | May 31 | — | 730–1095 |
| Beets | — | May 10 | — | Jul 5 – Aug 2 | 50–70 |
| Belgian Endive | Apr 5 | May 10 | May 17 | Sep 6 – Oct 11 | 110–150 |
| Black Beans | — | May 31 | — | Aug 30 – Oct 18 | 90–120 |
| Bok Choy | Apr 5 | May 10 | May 17 | Jun 28 – Aug 2 | 40–60 |
| Broccoli | Apr 5 | May 10 | May 17 | Jul 19 – Aug 30 | 60–90 |
| Broccoli Rabe | Apr 5 | May 10 | May 17 | Jun 28 – Aug 2 | 40–60 |
| Brussels Sprouts | Apr 5 | May 10 | May 17 | Aug 16 – Oct 11 | 90–130 |
| Butternut Squash | Apr 5 | May 31 | Jun 7 | Sep 6 – Oct 11 | 85–110 |
| Cabbage | Apr 5 | May 10 | May 17 | Jul 19 – Sep 13 | 60–100 |
| Carrots | — | May 10 | — | Jul 12 – Aug 16 | 60–80 |
| Cauliflower | Apr 5 | May 10 | May 17 | Jul 12 – Sep 13 | 55–100 |
| Celeriac | Apr 5 | May 10 | May 17 | Aug 30 – Oct 4 | 100–120 |
| Celery | Apr 5 | May 10 | May 17 | Aug 9 – Oct 4 | 80–120 |
| Celtuce | Apr 5 | May 10 | May 17 | Jul 19 – Aug 30 | 60–90 |
| Chard | Apr 5 | May 10 | May 17 | Jul 12 – Aug 30 | 50–60 |
| Chickpeas | Apr 5 | May 10 | May 17 | Aug 9 – Sep 20 | 80–110 |
| Chicory | Apr 5 | May 10 | May 17 | Jul 19 – Aug 30 | 60–85 |
| Chinese Cabbage | Apr 5 | May 10 | May 17 | Jul 12 – Aug 9 | 50–70 |
| Christmas Lima Beans | Mar 15 | May 31 | Jun 7 | Aug 30 – Oct 4 | 80–100 |
| Collard Greens | Apr 5 | May 10 | May 17 | Jul 12 – Sep 13 | 55–75 |
| Corn | — | May 31 | — | Aug 2 – Sep 27 | 60–100 |
| Cress | Apr 5 | May 10 | May 17 | May 31 – Jun 21 | 14–21 |
| Crookneck Squash | Apr 5 | May 31 | Jun 7 | Jul 26 – Aug 23 | 45–60 |
| Crosne | — | May 10 | — | Oct 11 – Oct 4 | 150–200 |
| Cucumber | Apr 5 | May 31 | Jun 7 | Aug 2 – Sep 27 | 50–70 |
| Daikon | — | May 10 | — | Jul 5 – Aug 2 | 50–70 |
| Delicata Squash | Apr 5 | May 31 | Jun 7 | Aug 30 – Oct 4 | 80–100 |
| Edamame | — | May 31 | — | Aug 16 – Sep 27 | 75–100 |
| Endive | Apr 5 | May 10 | May 17 | Jul 5 – Aug 9 | 45–65 |
| Escarole | Apr 5 | May 10 | May 17 | Jul 12 – Aug 9 | 50–70 |
| Fava Beans | Apr 5 | May 10 | May 17 | Aug 2 – Sep 13 | 75–100 |
| Fennel | Mar 15 | May 31 | Jun 7 | Aug 9 – Sep 20 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | May 31 | — | Jul 26 – Sep 20 | 50–65 |
| Horseradish | — | — | May 31 | Oct 4 – Oct 25 | 120–180 |
| Hubbard Squash | Apr 5 | May 31 | Jun 7 | Sep 20 – Oct 25 | 100–120 |
| Kabocha | Apr 5 | May 31 | Jun 7 | Sep 6 – Oct 4 | 85–100 |
| Kai Lan | Apr 5 | May 10 | May 17 | Jul 5 – Aug 2 | 45–60 |
| Kale | Apr 5 | May 10 | May 17 | Jul 12 – Sep 6 | 50–70 |
| Kidney Beans | — | May 31 | — | Aug 30 – Oct 4 | 85–110 |
| Kohlrabi | Apr 5 | May 10 | May 17 | Jul 5 – Aug 9 | 45–65 |
| Komatsuna | Apr 5 | May 10 | May 17 | Jun 21 – Jul 26 | 35–50 |
| Leeks | Apr 5 | May 10 | May 17 | Aug 16 – Oct 11 | 90–150 |
| Lentils | Apr 5 | May 10 | May 17 | Aug 9 – Sep 20 | 80–110 |
| Lettuce | Apr 5 | May 10 | May 17 | Jun 21 – Aug 30 | 30–60 |
| Lima Beans | — | May 31 | — | Aug 2 – Sep 13 | 60–90 |
| Mache | Apr 5 | May 10 | May 17 | Jun 28 – Aug 2 | 40–60 |
| Melon | Apr 5 | May 31 | Jun 7 | Aug 16 – Oct 4 | 70–100 |
| Microgreens | Apr 5 | May 10 | May 17 | May 24 – Jun 21 | 7–21 |
| Mitsuba | Apr 5 | May 10 | May 10 | Jul 5 – Aug 30 | 50–70 |
| Mizuna | Apr 5 | May 10 | May 17 | Jun 21 – Jul 19 | 30–45 |
| Mustard Greens | Apr 5 | May 10 | May 17 | Jun 21 – Aug 23 | 30–50 |
| Napa Cabbage | Apr 5 | May 10 | May 17 | Jul 12 – Aug 16 | 55–75 |
| Onion | Apr 5 | May 10 | May 17 | Aug 16 – Oct 4 | 90–120 |
| Pac Choi | Apr 5 | May 10 | May 17 | Jun 28 – Jul 26 | 40–55 |
| Parsnip | — | May 10 | — | Aug 23 – Oct 4 | 100–130 |
| Patty Pan Squash | Apr 5 | May 31 | Jun 7 | Jul 26 – Aug 23 | 45–60 |
| Peas | Apr 5 | May 10 | May 17 | Jul 12 – Sep 6 | 55–70 |
| Peppers | Mar 1 | May 31 | Jun 7 | Aug 9 – Oct 18 | 60–90 |
| Pole Beans | Mar 15 | May 31 | Jun 7 | Aug 2 – Sep 27 | 55–70 |
| Potatoes | Mar 15 | May 31 | Jun 7 | Aug 16 – Oct 25 | 70–120 |
| Pumpkin | Apr 5 | May 31 | Jun 7 | Sep 6 – Oct 25 | 85–120 |
| Purslane | Apr 5 | May 10 | May 17 | Jun 28 – Aug 2 | 40–60 |
| Radicchio | Apr 5 | May 10 | May 17 | Jul 19 – Aug 23 | 60–80 |
| Radish | — | May 10 | — | Jun 7 – Jun 28 | 22–35 |
| Rhubarb | — | — | Jun 14 | — | 365–730 |
| Romanesco | Apr 5 | May 10 | May 17 | Aug 2 – Sep 13 | 75–100 |
| Rutabaga | — | May 10 | — | Aug 2 – Sep 6 | 80–100 |
| Salsify | — | May 10 | — | Aug 23 – Oct 4 | 100–130 |
| Savoy Cabbage | Apr 5 | May 10 | May 17 | Jul 26 – Sep 20 | 70–110 |
| Scallions | Apr 5 | May 10 | May 17 | Jul 12 – Aug 9 | 50–70 |
| Scarlet Runner Beans | Mar 15 | May 31 | Jun 7 | Aug 9 – Sep 13 | 60–80 |
| Shallot | Apr 5 | May 10 | May 17 | Aug 16 – Oct 4 | 90–120 |
| Shiso | Mar 22 | May 24 | Jun 7 | Aug 2 – Sep 27 | 50–70 |
| Snap Peas | Mar 15 | May 31 | Jun 7 | Aug 2 – Sep 27 | 55–70 |
| Snow Peas | Apr 5 | May 10 | May 17 | Jul 12 – Sep 6 | 50–65 |
| Soybeans | — | May 31 | — | Aug 23 – Oct 18 | 80–120 |
| Spaghetti Squash | Apr 5 | May 31 | Jun 7 | Sep 6 – Oct 4 | 85–100 |
| Spinach | Apr 5 | May 10 | May 17 | Jun 21 – Aug 23 | 35–50 |
| Squash (Summer) | Apr 5 | May 31 | Jun 7 | Jul 26 – Sep 27 | 45–65 |
| Squash (Winter) | Apr 5 | May 31 | Jun 7 | Aug 30 – Oct 25 | 80–120 |
| Sunchoke | — | — | May 31 | Sep 20 – Oct 25 | 110–150 |
| Sunflower | Mar 15 | May 31 | Jun 7 | Aug 16 – Oct 4 | 70–100 |
| Sweet Corn | — | May 31 | — | Aug 2 – Sep 13 | 60–90 |
| Tatsoi | Apr 5 | May 10 | May 17 | Jun 21 – Jul 26 | 35–50 |
| Tomatillo | Mar 15 | May 31 | Jun 7 | Aug 9 – Oct 18 | 60–85 |
| Tomatoes | Mar 15 | May 31 | Jun 7 | Aug 9 – Oct 18 | 60–85 |
| Turnip | — | May 10 | — | Jun 21 – Jul 26 | 40–60 |
| Watercress | Apr 5 | May 10 | May 17 | Jun 28 – Aug 2 | 40–60 |
| Watermelon | Apr 5 | May 31 | Jun 7 | Aug 16 – Oct 4 | 70–100 |
| Wax Beans | — | May 31 | — | Jul 26 – Sep 20 | 50–65 |
| Zucchini | Apr 5 | May 31 | Jun 7 | Jul 26 – Sep 20 | 45–60 |
🍓 Fruits to Grow in Johnson County
22 fruits that grow well in Zone 4a with planting dates for Johnson County.
Show all 22 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 14 | Sep 13 – Nov 8 | 90–180 |
| Aronia | — | — | Jun 14 | — | 730–1095 |
| Blueberries | — | — | Jun 14 | — | 730–1095 |
| Cantaloupe | — | — | Jun 14 | Aug 23 – Sep 27 | 70–90 |
| Cranberries | — | — | Jun 14 | — | 730–1095 |
| Currants | — | — | Jun 14 | — | 730–1095 |
| Elderberries | — | — | Jun 14 | — | 730–1095 |
| Goji Berries | — | — | Jun 14 | — | 730–1095 |
| Gooseberries | — | — | Jun 14 | — | 730–1095 |
| Grapes | — | — | Jun 14 | — | 730–1095 |
| Ground Cherry | — | — | Jun 14 | Aug 23 – Oct 18 | 65–80 |
| Hardy Kiwi | — | — | Jun 14 | — | 1095–1825 |
| Haskaps | — | — | Jun 14 | — | 730–1095 |
| Honeydew | — | — | Jun 14 | Sep 6 – Oct 18 | 80–110 |
| Jostaberry | — | — | Jun 14 | — | 730–1095 |
| Lingonberries | — | — | Jun 14 | — | 730–1095 |
| Medlar | — | — | Jun 14 | — | 1095–1825 |
| Mulberries | — | — | Jun 14 | — | 730–1825 |
| Persimmon | — | — | Jun 14 | — | 1095–2555 |
| Raspberries | — | — | Jun 14 | — | 365–730 |
| Serviceberries | — | — | Jun 14 | — | 730–1095 |
| Strawberries | — | — | Jun 14 | Sep 13 – Nov 8 | 90–365 |
🌿 Herbs to Grow in Johnson County
32 herbs that grow well in Zone 4a with planting dates for Johnson County.
Show all 32 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 5 | May 10 | May 10 | — | 365–730 |
| Anise | Apr 5 | May 10 | May 10 | Aug 9 – Oct 4 | 90–120 |
| Basil | Mar 22 | May 24 | Jun 7 | Aug 2 – Oct 4 | 50–75 |
| Bee Balm | — | — | May 24 | Aug 23 – Oct 18 | 90–120 |
| Borage | Apr 5 | May 10 | May 10 | Jul 5 – Aug 23 | 50–60 |
| Caraway | Apr 5 | May 10 | May 10 | — | 365–450 |
| Catnip | — | — | May 24 | Jul 26 – Sep 27 | 60–80 |
| Chamomile | Apr 5 | May 10 | May 10 | Jul 12 – Sep 20 | 60–90 |
| Chervil | Apr 5 | May 10 | May 10 | Jun 21 – Aug 23 | 40–60 |
| Chives | — | — | May 24 | Jul 26 – Oct 4 | 60–90 |
| Cilantro | Apr 5 | May 10 | May 10 | Jun 21 – Aug 23 | 40–60 |
| Comfrey | — | — | May 24 | Jul 26 – Oct 4 | 60–90 |
| Dill | Apr 5 | May 10 | May 10 | Jun 21 – Aug 23 | 40–60 |
| Echinacea | — | — | May 24 | Sep 27 – Oct 18 | 120–180 |
| Fennel (herb) | Apr 5 | May 10 | May 10 | Jul 12 – Sep 20 | 60–90 |
| Garlic Chives | — | — | May 24 | Jul 26 – Oct 4 | 60–90 |
| Horehound | — | — | May 24 | Aug 9 – Oct 4 | 75–90 |
| Hyssop | — | — | May 24 | Aug 2 – Oct 4 | 70–90 |
| Lemon Balm | — | — | May 24 | Jul 26 – Sep 13 | 60–70 |
| Lovage | — | — | May 24 | Aug 2 – Oct 4 | 70–90 |
| Mint | — | — | May 24 | Jul 26 – Oct 4 | 60–90 |
| Oregano | — | — | May 24 | Jul 26 – Oct 4 | 60–90 |
| Parsley | Apr 5 | May 10 | May 10 | Jul 12 – Sep 13 | 60–80 |
| Rue | — | — | May 24 | Aug 2 – Oct 4 | 70–90 |
| Sage | — | — | May 24 | Aug 9 – Oct 4 | 75–90 |
| Savory | — | — | May 24 | Jul 19 – Sep 13 | 50–70 |
| Sorrel | Apr 5 | May 10 | May 10 | Jun 21 – Aug 23 | 40–60 |
| Tarragon | — | — | May 24 | Jul 26 – Oct 4 | 60–90 |
| Thai Basil | Mar 22 | May 24 | Jun 7 | Aug 2 – Oct 4 | 50–75 |
| Thyme | — | — | May 24 | Aug 2 – Oct 4 | 70–90 |
| Valerian | — | — | May 24 | Sep 27 – Oct 18 | 120–180 |
| Yarrow | — | — | May 24 | Aug 23 – Oct 18 | 90–120 |
Monthly Planting Guide for Johnson County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Johnson County.
Frequently Asked Questions
What planting zone is Johnson County, WY?
Johnson County is in USDA Hardiness Zone 4a. 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 Johnson County, WY?
Based on 31 years of NOAA weather station data, the median last spring frost in Johnson County falls around May 17. In 8 out of 10 years, last frost lands between May 5 and June 7 — a 32-day window of variability. Use June 7 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Johnson County, WY?
The median first fall frost in Johnson County arrives around September 21. In cold years it can arrive as early as September 6; in mild years as late as October 7. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Johnson County?
Johnson County has a frost-free growing season of approximately 127 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 1.95 days per decade.
What is the soil like in Johnson County for gardening?
Johnson County has predominantly Loam soil with a pH range of 6.8–7.8 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Johnson County?
Johnson County has commercial agriculture that includes Cattle, Hay, Wheat, Barley. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Johnson County a good location for home gardening?
Johnson County scores 39/100 (Challenging) on our Microclimate Index, which combines frost reliability, drought pressure, soil challenge, elevation risk, and long-term climate trend. Gardening here benefits from close attention to frost timing and season extension due to the challenging microclimate factors.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Johnson County gardeners in Zone 4a 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.
