Custer County, ID — Planting Guide
Custer County is in USDA Zone 4a. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.
At an elevation of 5,189 ft, Custer County receives approximately 20.6 in of rainfall annually. Summer highs average 80°F with winter lows around 5°F. The predominant soil type is Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 38 days year to year — ranging from May 21 in warm years to June 29 in cold years. The growing season is trending longer by about 2.4 days per decade. Custer County scores 36/100 (Challenging) on the Microclimate Index.
🌡️ Zone
4a (-30°F to -25°F min)
❄️ Last Frost
June 18
🍂 First Frost
September 5
📅 Growing Season
79 days
⛰️ Elevation
5,189 ft
🌧️ Annual Rainfall
20.6 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 | 1.3 in | 6 days | — | None |
| Feb | 1.3 in | 5 days | — | None |
| Mar | 1.7 in | 8 days | — | None |
| Apr | 2.4 in | 8 days | 1.9 in | High |
| May | 2.3 in | 8 days | 2 in | High |
| Jun | 1.5 in | 4 days | 2.8 in | High |
| Jul | 2 in | 6 days | 2.3 in | High |
| Aug | 2.1 in | 6 days | 2.2 in | High |
| Sep | 1.7 in | 6 days | 2.6 in | High |
| Oct | 1.6 in | 5 days | 2.7 in | High |
| Nov | 1.4 in | 6 days | — | None |
| Dec | 1.2 in | 6 days | — | None |
Annual total: 20.5 in. Gardens typically need ~1 inch of water per week during the growing season. Months marked "None" for extra water are outside the active growing season for your zone — most gardens are dormant and don't need irrigation during those months.
Custer County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
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 29 | Sep 28 | 91 days |
| Cautious | Jun 23 | Sep 9 | 78 days |
| Average year | Jun 18 | Sep 5 | 79 days |
| Optimistic | Jun 11 | Aug 15 | 65 days |
| Aggressive (risky) | May 21 | Aug 1 | 72 days |
Not very — frost dates can vary by ±38 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 2.4 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Custer County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Custer 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 Custer County's climate and soil.
County Extension Office
Custer County University of Idaho Extension Extension Office
Phone: 208-885-6681
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 Custer County
Finding local nurseries & garden centers in Custer County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Custer 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 Custer County ID" or "garden center Custer 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 Custer County ID" or check your extension office and local parks department. Facebook groups like "Custer County Gardeners" or "Idaho 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
11.3 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 hr | 4.8 hr | Short day |
| February | 10.2 hr | 5.9 hr | Short day |
| March | 11.6 hr | 7.2 hr | Short day |
| April | 13.2 hr | 7.4 hr | Neutral |
| May | 14.6 hr | 9 hr | Long day |
| June | 15.3 hr | 11.3 hr | Long day |
| July | 15 hr | 11 hr | Long day |
| August | 13.8 hr | 9.7 hr | Neutral |
| September | 12.3 hr | 8.6 hr | Neutral |
| October | 10.7 hr | 7.2 hr | Short day |
| November | 9.4 hr | 5.5 hr | Short day |
| December | 8.7 hr | 4.7 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
Jun
Microbial activity peaks when soil is warm.
Active Composting
4 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 | -1°F | 9°F | ❄️ Dormant | ~36 weeks |
| Feb | 3°F | 7°F | ❄️ Dormant | ~36 weeks |
| Mar | 11°F | 15°F | ❄️ Dormant | ~36 weeks |
| Apr | 28°F | 26°F | ❄️ Dormant | ~36 weeks |
| May | 40°F | 37°F | ❄️ Dormant | ~36 weeks |
| Jun | 51°F | 44°F | ♻️ Active | ~14 weeks |
| Jul | 60°F | 52°F | ♻️ Active | ~14 weeks |
| Aug | 59°F | 53°F | ♻️ Active | ~14 weeks |
| Sep | 51°F | 51°F | ♻️ Active | ~14 weeks |
| Oct | 36°F | 40°F | ❄️ Dormant | ~36 weeks |
| Nov | 22°F | 30°F | ❄️ Dormant | ~36 weeks |
| Dec | 8°F | 17°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 Custer County
Computed from local climate patterns — warmer, humid conditions increase pest generations and fungal disease risk.
Insect Pest Pressure
Low — basic prevention and occasional hand-picking.
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 | Moderate | May, Jun, Jul |
| Slugs | Moderate | 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 Custer County
Cover crops protect bare soil, fix nitrogen, suppress weeds, and improve soil structure — with county-specific planting dates.
Fall Cover Crops (5 options) — Plant after harvest to protect soil over winter
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Daikon radish | Jul 27 | Jun 4 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jun 15 | Jun 4 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 4 | Jun 4 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | May 29 | May 28 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 7 | May 28 | — | Erosion control, weed suppression, good biomass |
Spring Cover Crops (2 options) — Build soil before the main growing season
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Buckwheat | Jun 28 | Jul 4 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | May 24 | Jun 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 | Jul 12 | Aug 8 | — | Deep roots break compaction, attract pollinators and beneficial insects |
Wind & Microclimate
Wind dries soil, stresses plants, and affects frost patterns. Understanding your exposure helps with garden placement.
Seasonal Wind Speed
Spring: 14 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
6.9/10
Moderately beneficial — a simple fence or trellis can protect delicate crops from wind stress.
Frost Pocket Risk
High
Hilly terrain with 2,419 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
10,217 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
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 20.5 inches of rain per year
- A 1,000 sq ft roof can collect roughly 10,217 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 Custer County
Soil Type
Loam
Soil pH 6.3–8 · Moderately Well 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
79-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 Custer County
96 vegetables that grow well in Zone 4a with planting dates for Custer County.
Show all 96 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | May 7 | Jul 2 | Jul 9 | Oct 1 – Nov 5 | 80–100 |
| Amaranth | Apr 16 | Jul 2 | Jul 9 | Oct 8 – Nov 26 | 90–120 |
| Arugula | May 7 | Jun 11 | Jun 18 | Jul 23 – Sep 24 | 30–50 |
| Asparagus | — | — | Jul 2 | — | 730–1095 |
| Beets | — | Jun 11 | — | Aug 6 – Sep 3 | 50–70 |
| Belgian Endive | May 7 | Jun 11 | Jun 18 | Oct 8 – Nov 12 | 110–150 |
| Black Beans | — | Jul 2 | — | Oct 1 – Nov 19 | 90–120 |
| Bok Choy | May 7 | Jun 11 | Jun 18 | Jul 30 – Sep 3 | 40–60 |
| Broccoli | May 7 | Jun 11 | Jun 18 | Aug 20 – Oct 1 | 60–90 |
| Broccoli Rabe | May 7 | Jun 11 | Jun 18 | Jul 30 – Sep 3 | 40–60 |
| Brussels Sprouts | May 7 | Jun 11 | Jun 18 | Sep 17 – Nov 12 | 90–130 |
| Butternut Squash | May 7 | Jul 2 | Jul 9 | Oct 8 – Nov 12 | 85–110 |
| Cabbage | May 7 | Jun 11 | Jun 18 | Aug 20 – Oct 15 | 60–100 |
| Carrots | — | Jun 11 | — | Aug 13 – Sep 17 | 60–80 |
| Cauliflower | May 7 | Jun 11 | Jun 18 | Aug 13 – Oct 15 | 55–100 |
| Celeriac | May 7 | Jun 11 | Jun 18 | Oct 1 – Nov 5 | 100–120 |
| Celery | May 7 | Jun 11 | Jun 18 | Sep 10 – Nov 5 | 80–120 |
| Celtuce | May 7 | Jun 11 | Jun 18 | Aug 20 – Oct 1 | 60–90 |
| Chard | May 7 | Jun 11 | Jun 18 | Aug 13 – Oct 1 | 50–60 |
| Chickpeas | May 7 | Jun 11 | Jun 18 | Sep 10 – Oct 22 | 80–110 |
| Chicory | May 7 | Jun 11 | Jun 18 | Aug 20 – Oct 1 | 60–85 |
| Chinese Cabbage | May 7 | Jun 11 | Jun 18 | Aug 13 – Sep 10 | 50–70 |
| Christmas Lima Beans | Apr 16 | Jul 2 | Jul 9 | Oct 1 – Nov 5 | 80–100 |
| Collard Greens | May 7 | Jun 11 | Jun 18 | Aug 13 – Oct 15 | 55–75 |
| Corn | — | Jul 2 | — | Sep 3 – Oct 29 | 60–100 |
| Cress | May 7 | Jun 11 | Jun 18 | Jul 2 – Jul 23 | 14–21 |
| Crookneck Squash | May 7 | Jul 2 | Jul 9 | Aug 27 – Sep 24 | 45–60 |
| Crosne | — | Jun 11 | — | Nov 12 – Nov 5 | 150–200 |
| Cucumber | May 7 | Jul 2 | Jul 9 | Sep 3 – Oct 29 | 50–70 |
| Daikon | — | Jun 11 | — | Aug 6 – Sep 3 | 50–70 |
| Delicata Squash | May 7 | Jul 2 | Jul 9 | Oct 1 – Nov 5 | 80–100 |
| Edamame | — | Jul 2 | — | Sep 17 – Oct 29 | 75–100 |
| Endive | May 7 | Jun 11 | Jun 18 | Aug 6 – Sep 10 | 45–65 |
| Escarole | May 7 | Jun 11 | Jun 18 | Aug 13 – Sep 10 | 50–70 |
| Fava Beans | May 7 | Jun 11 | Jun 18 | Sep 3 – Oct 15 | 75–100 |
| Fennel | Apr 16 | Jul 2 | Jul 9 | Sep 10 – Oct 22 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Jul 2 | — | Aug 27 – Oct 22 | 50–65 |
| Horseradish | — | — | Jul 2 | Nov 5 – Nov 26 | 120–180 |
| Hubbard Squash | May 7 | Jul 2 | Jul 9 | Oct 22 – Nov 26 | 100–120 |
| Kabocha | May 7 | Jul 2 | Jul 9 | Oct 8 – Nov 5 | 85–100 |
| Kai Lan | May 7 | Jun 11 | Jun 18 | Aug 6 – Sep 3 | 45–60 |
| Kale | May 7 | Jun 11 | Jun 18 | Aug 13 – Oct 8 | 50–70 |
| Kidney Beans | — | Jul 2 | — | Oct 1 – Nov 5 | 85–110 |
| Kohlrabi | May 7 | Jun 11 | Jun 18 | Aug 6 – Sep 10 | 45–65 |
| Komatsuna | May 7 | Jun 11 | Jun 18 | Jul 23 – Aug 27 | 35–50 |
| Leeks | May 7 | Jun 11 | Jun 18 | Sep 17 – Nov 12 | 90–150 |
| Lentils | May 7 | Jun 11 | Jun 18 | Sep 10 – Oct 22 | 80–110 |
| Lettuce | May 7 | Jun 11 | Jun 18 | Jul 23 – Oct 1 | 30–60 |
| Lima Beans | — | Jul 2 | — | Sep 3 – Oct 15 | 60–90 |
| Mache | May 7 | Jun 11 | Jun 18 | Jul 30 – Sep 3 | 40–60 |
| Melon | May 7 | Jul 2 | Jul 9 | Sep 17 – Nov 5 | 70–100 |
| Microgreens | May 7 | Jun 11 | Jun 18 | Jun 25 – Jul 23 | 7–21 |
| Mitsuba | May 7 | Jun 11 | Jun 11 | Aug 6 – Oct 1 | 50–70 |
| Mizuna | May 7 | Jun 11 | Jun 18 | Jul 23 – Aug 20 | 30–45 |
| Mustard Greens | May 7 | Jun 11 | Jun 18 | Jul 23 – Sep 24 | 30–50 |
| Napa Cabbage | May 7 | Jun 11 | Jun 18 | Aug 13 – Sep 17 | 55–75 |
| Onion | May 7 | Jun 11 | Jun 18 | Sep 17 – Nov 5 | 90–120 |
| Pac Choi | May 7 | Jun 11 | Jun 18 | Jul 30 – Aug 27 | 40–55 |
| Parsnip | — | Jun 11 | — | Sep 24 – Nov 5 | 100–130 |
| Patty Pan Squash | May 7 | Jul 2 | Jul 9 | Aug 27 – Sep 24 | 45–60 |
| Peas | May 7 | Jun 11 | Jun 18 | Aug 13 – Oct 8 | 55–70 |
| Peppers | Apr 2 | Jul 2 | Jul 9 | Sep 10 – Nov 19 | 60–90 |
| Pole Beans | Apr 16 | Jul 2 | Jul 9 | Sep 3 – Oct 29 | 55–70 |
| Potatoes | Apr 16 | Jul 2 | Jul 9 | Sep 17 – Nov 26 | 70–120 |
| Pumpkin | May 7 | Jul 2 | Jul 9 | Oct 8 – Nov 26 | 85–120 |
| Purslane | May 7 | Jun 11 | Jun 18 | Jul 30 – Sep 3 | 40–60 |
| Radicchio | May 7 | Jun 11 | Jun 18 | Aug 20 – Sep 24 | 60–80 |
| Radish | — | Jun 11 | — | Jul 9 – Jul 30 | 22–35 |
| Rhubarb | — | — | Jul 16 | — | 365–730 |
| Romanesco | May 7 | Jun 11 | Jun 18 | Sep 3 – Oct 15 | 75–100 |
| Rutabaga | — | Jun 11 | — | Sep 3 – Oct 8 | 80–100 |
| Salsify | — | Jun 11 | — | Sep 24 – Nov 5 | 100–130 |
| Savoy Cabbage | May 7 | Jun 11 | Jun 18 | Aug 27 – Oct 22 | 70–110 |
| Scallions | May 7 | Jun 11 | Jun 18 | Aug 13 – Sep 10 | 50–70 |
| Scarlet Runner Beans | Apr 16 | Jul 2 | Jul 9 | Sep 10 – Oct 15 | 60–80 |
| Shallot | May 7 | Jun 11 | Jun 18 | Sep 17 – Nov 5 | 90–120 |
| Shiso | Apr 23 | Jun 25 | Jul 9 | Sep 3 – Oct 29 | 50–70 |
| Snap Peas | Apr 16 | Jul 2 | Jul 9 | Sep 3 – Oct 29 | 55–70 |
| Snow Peas | May 7 | Jun 11 | Jun 18 | Aug 13 – Oct 8 | 50–65 |
| Soybeans | — | Jul 2 | — | Sep 24 – Nov 19 | 80–120 |
| Spaghetti Squash | May 7 | Jul 2 | Jul 9 | Oct 8 – Nov 5 | 85–100 |
| Spinach | May 7 | Jun 11 | Jun 18 | Jul 23 – Sep 24 | 35–50 |
| Squash (Summer) | May 7 | Jul 2 | Jul 9 | Aug 27 – Oct 29 | 45–65 |
| Squash (Winter) | May 7 | Jul 2 | Jul 9 | Oct 1 – Nov 26 | 80–120 |
| Sunchoke | — | — | Jul 2 | Oct 22 – Nov 26 | 110–150 |
| Sunflower | Apr 16 | Jul 2 | Jul 9 | Sep 17 – Nov 5 | 70–100 |
| Sweet Corn | — | Jul 2 | — | Sep 3 – Oct 15 | 60–90 |
| Tatsoi | May 7 | Jun 11 | Jun 18 | Jul 23 – Aug 27 | 35–50 |
| Tomatillo | Apr 16 | Jul 2 | Jul 9 | Sep 10 – Nov 19 | 60–85 |
| Tomatoes | Apr 16 | Jul 2 | Jul 9 | Sep 10 – Nov 19 | 60–85 |
| Turnip | — | Jun 11 | — | Jul 23 – Aug 27 | 40–60 |
| Watercress | May 7 | Jun 11 | Jun 18 | Jul 30 – Sep 3 | 40–60 |
| Watermelon | May 7 | Jul 2 | Jul 9 | Sep 17 – Nov 5 | 70–100 |
| Wax Beans | — | Jul 2 | — | Aug 27 – Oct 22 | 50–65 |
| Zucchini | May 7 | Jul 2 | Jul 9 | Aug 27 – Oct 22 | 45–60 |
🍓 Fruits to Grow in Custer County
22 fruits that grow well in Zone 4a with planting dates for Custer County.
Show all 22 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jul 16 | Oct 15 – Dec 10 | 90–180 |
| Aronia | — | — | Jul 16 | — | 730–1095 |
| Blueberries | — | — | Jul 16 | — | 730–1095 |
| Cantaloupe | — | — | Jul 16 | Sep 24 – Oct 29 | 70–90 |
| Cranberries | — | — | Jul 16 | — | 730–1095 |
| Currants | — | — | Jul 16 | — | 730–1095 |
| Elderberries | — | — | Jul 16 | — | 730–1095 |
| Goji Berries | — | — | Jul 16 | — | 730–1095 |
| Gooseberries | — | — | Jul 16 | — | 730–1095 |
| Grapes | — | — | Jul 16 | — | 730–1095 |
| Ground Cherry | — | — | Jul 16 | Sep 24 – Nov 19 | 65–80 |
| Hardy Kiwi | — | — | Jul 16 | — | 1095–1825 |
| Haskaps | — | — | Jul 16 | — | 730–1095 |
| Honeydew | — | — | Jul 16 | Oct 8 – Nov 19 | 80–110 |
| Jostaberry | — | — | Jul 16 | — | 730–1095 |
| Lingonberries | — | — | Jul 16 | — | 730–1095 |
| Medlar | — | — | Jul 16 | — | 1095–1825 |
| Mulberries | — | — | Jul 16 | — | 730–1825 |
| Persimmon | — | — | Jul 16 | — | 1095–2555 |
| Raspberries | — | — | Jul 16 | — | 365–730 |
| Serviceberries | — | — | Jul 16 | — | 730–1095 |
| Strawberries | — | — | Jul 16 | Oct 15 – Dec 10 | 90–365 |
🌿 Herbs to Grow in Custer County
32 herbs that grow well in Zone 4a with planting dates for Custer County.
Show all 32 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | May 7 | Jun 11 | Jun 11 | — | 365–730 |
| Anise | May 7 | Jun 11 | Jun 11 | Sep 10 – Nov 5 | 90–120 |
| Basil | Apr 23 | Jun 25 | Jul 9 | Sep 3 – Nov 5 | 50–75 |
| Bee Balm | — | — | Jun 25 | Sep 24 – Nov 19 | 90–120 |
| Borage | May 7 | Jun 11 | Jun 11 | Aug 6 – Sep 24 | 50–60 |
| Caraway | May 7 | Jun 11 | Jun 11 | — | 365–450 |
| Catnip | — | — | Jun 25 | Aug 27 – Oct 29 | 60–80 |
| Chamomile | May 7 | Jun 11 | Jun 11 | Aug 13 – Oct 22 | 60–90 |
| Chervil | May 7 | Jun 11 | Jun 11 | Jul 23 – Sep 24 | 40–60 |
| Chives | — | — | Jun 25 | Aug 27 – Nov 5 | 60–90 |
| Cilantro | May 7 | Jun 11 | Jun 11 | Jul 23 – Sep 24 | 40–60 |
| Comfrey | — | — | Jun 25 | Aug 27 – Nov 5 | 60–90 |
| Dill | May 7 | Jun 11 | Jun 11 | Jul 23 – Sep 24 | 40–60 |
| Echinacea | — | — | Jun 25 | Oct 29 – Nov 19 | 120–180 |
| Fennel (herb) | May 7 | Jun 11 | Jun 11 | Aug 13 – Oct 22 | 60–90 |
| Garlic Chives | — | — | Jun 25 | Aug 27 – Nov 5 | 60–90 |
| Horehound | — | — | Jun 25 | Sep 10 – Nov 5 | 75–90 |
| Hyssop | — | — | Jun 25 | Sep 3 – Nov 5 | 70–90 |
| Lemon Balm | — | — | Jun 25 | Aug 27 – Oct 15 | 60–70 |
| Lovage | — | — | Jun 25 | Sep 3 – Nov 5 | 70–90 |
| Mint | — | — | Jun 25 | Aug 27 – Nov 5 | 60–90 |
| Oregano | — | — | Jun 25 | Aug 27 – Nov 5 | 60–90 |
| Parsley | May 7 | Jun 11 | Jun 11 | Aug 13 – Oct 15 | 60–80 |
| Rue | — | — | Jun 25 | Sep 3 – Nov 5 | 70–90 |
| Sage | — | — | Jun 25 | Sep 10 – Nov 5 | 75–90 |
| Savory | — | — | Jun 25 | Aug 20 – Oct 15 | 50–70 |
| Sorrel | May 7 | Jun 11 | Jun 11 | Jul 23 – Sep 24 | 40–60 |
| Tarragon | — | — | Jun 25 | Aug 27 – Nov 5 | 60–90 |
| Thai Basil | Apr 23 | Jun 25 | Jul 9 | Sep 3 – Nov 5 | 50–75 |
| Thyme | — | — | Jun 25 | Sep 3 – Nov 5 | 70–90 |
| Valerian | — | — | Jun 25 | Oct 29 – Nov 19 | 120–180 |
| Yarrow | — | — | Jun 25 | Sep 24 – Nov 19 | 90–120 |
Monthly Planting Guide for Custer County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Custer County.
Frequently Asked Questions
What planting zone is Custer County, ID?
Custer 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 Custer County, ID?
Based on 31 years of NOAA weather station data, the median last spring frost in Custer County falls around June 18. In 8 out of 10 years, last frost lands between May 21 and June 29 — a 38-day window of variability. Use June 29 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Custer County, ID?
The median first fall frost in Custer County arrives around September 5. In cold years it can arrive as early as August 1; in mild years as late as September 28. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Custer County?
Custer County has a frost-free growing season of approximately 79 days. Focus on short-season varieties and start warm-season crops indoors 6–8 weeks before last frost. Climate records show the growing season is trending longer by about 2.4 days per decade.
What is the soil like in Custer County for gardening?
Custer County has predominantly Loam soil with a pH range of 6.3–8 and Moderately Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Custer County?
Custer County has commercial agriculture that includes Potatoes, Wheat, Cattle, Hay, Barley. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Custer County a good location for home gardening?
Custer County scores 36/100 (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 Custer 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.
