Caribou County, ID — Planting Guide
Caribou County is in USDA Zone 4b. The average last spring frost is May 30 and the first fall frost is September 16, giving you a growing season of approximately 109 days.
At an elevation of 6,562 ft, Caribou County receives approximately 15.3 in of rainfall annually. Summer highs average 81°F with winter lows around 8°F. The predominant soil type is Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 40 days year to year — ranging from May 8 in warm years to June 17 in cold years. The growing season is trending longer by about 1.97 days per decade. Caribou County scores 30/100 (Challenging) on the Microclimate Index.
🌡️ Zone
4b (-25°F to -20°F min)
❄️ Last Frost
May 30
🍂 First Frost
September 16
📅 Growing Season
109 days
⛰️ Elevation
6,562 ft
🌧️ Annual Rainfall
15.3 in
Monthly Watering Calendar
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 1.2 in | 7 days | — | None |
| Feb | 0.9 in | 6 days | — | None |
| Mar | 1.4 in | 7 days | — | None |
| Apr | 1.7 in | 7 days | 2.6 in | High |
| May | 1.6 in | 8 days | 2.7 in | High |
| Jun | 1 in | 4 days | 3.3 in | Critical |
| Jul | 1.5 in | 6 days | 2.8 in | High |
| Aug | 1.4 in | 6 days | 2.9 in | High |
| Sep | 1.2 in | 5 days | 3.1 in | Critical |
| Oct | 1.4 in | 6 days | 2.9 in | High |
| Nov | 1.1 in | 5 days | — | None |
| Dec | 0.9 in | 7 days | — | None |
Annual total: 15.3 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.
Caribou County Soil Profile
Soil Type
Loam
Soil pH
6.8-8.1
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 17 | Oct 9 | 114 days |
| Cautious | Jun 11 | Sep 22 | 103 days |
| Average year | May 30 | Sep 16 | 109 days |
| Optimistic | May 18 | Sep 8 | 113 days |
| Aggressive (risky) | May 8 | Sep 2 | 117 days |
Not very — frost dates can vary by ±40 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
Caribou County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Caribou 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 Caribou County's climate and soil.
County Extension Office
Caribou 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 Caribou County
Finding local nurseries & garden centers in Caribou County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Caribou 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 Caribou County ID" or "garden center Caribou 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 Caribou County ID" or check your extension office and local parks department. Facebook groups like "Caribou 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
15.1 hours
Summer solstice daylight
Shortest Day
8.9 hours
Winter solstice daylight
Peak Sun Hours
10.5 hr/day peak (summer)
Peak sun hours (green dashed line below) account for cloud cover — this is the usable direct sunlight your garden actually receives. Most vegetables need 6+ peak sun hours.
Onion tip: Your long summer days (14+ hours) support long-day onion varieties like Walla Walla, Sweet Spanish, and Ailsa Craig.
View detailed monthly data
| Month | Daylight Hours | Peak Sun Hours | Day Length |
|---|---|---|---|
| January | 9.2 hr | 5.3 hr | Short day |
| February | 10.3 hr | 6.1 hr | Short day |
| March | 11.7 hr | 7.2 hr | Short day |
| April | 13.2 hr | 7.9 hr | Neutral |
| May | 14.4 hr | 9.2 hr | Long day |
| June | 15.1 hr | 10.5 hr | Long day |
| July | 14.9 hr | 10.5 hr | Long day |
| August | 13.7 hr | 9 hr | Neutral |
| September | 12.3 hr | 8.4 hr | Neutral |
| October | 10.8 hr | 7.2 hr | Short day |
| November | 9.5 hr | 5.3 hr | Short day |
| December | 8.9 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
Jul
Microbial activity peaks when soil is warm.
Active Composting
2 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 | -3°F | 5°F | ❄️ Dormant | ~36 weeks |
| Feb | -2°F | 5°F | ❄️ Dormant | ~36 weeks |
| Mar | 8°F | 9°F | ❄️ Dormant | ~36 weeks |
| Apr | 22°F | 19°F | ❄️ Dormant | ~36 weeks |
| May | 34°F | 32°F | ❄️ Dormant | ~36 weeks |
| Jun | 44°F | 39°F | 🐢 Slow | ~24 weeks |
| Jul | 55°F | 49°F | ♻️ Active | ~14 weeks |
| Aug | 53°F | 48°F | ♻️ Active | ~14 weeks |
| Sep | 46°F | 44°F | 🐢 Slow | ~24 weeks |
| Oct | 34°F | 37°F | ❄️ Dormant | ~36 weeks |
| Nov | 18°F | 23°F | ❄️ Dormant | ~36 weeks |
| Dec | 4°F | 13°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 Caribou 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 | Moderate | Jun, Jul, Aug |
| Colorado potato beetle | Moderate | Jun, Jul |
| Flea beetles | Low | 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 Caribou 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 21 | May 16 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jun 26 | May 16 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Aug 19 | May 16 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 13 | May 16 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | Jun 20 | May 16 | — | 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 7 | Jul 22 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | Apr 30 | Jul 22 | ✓ Yes | Living mulch, fixes nitrogen, permanent ground cover |
Summer Cover Crops (1 options) — Fill gaps and suppress weeds between plantings
| Crop | Plant By | Terminate | N-Fixing | Soil Benefit |
|---|---|---|---|---|
| Sunflowers | Jun 16 | Sep 2 | — | 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: 16 mph Summer: 11 mph
Fall: 13 mph Winter: 16 mph
Prevailing wind: W. Windy area — plant a windbreak hedge on the W side of your garden.
Windbreak Benefit
9.3/10
Strongly recommended — a windbreak (fence, hedge, or row of tall crops like corn or sunflowers) will significantly improve garden yields.
Frost Pocket Risk
High
Hilly terrain with 1,082 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
7,625 gal
Per 1,000 sq ft of roof area (at 80% collection efficiency)
Recommended Setup
8 rain barrels (55 gal each)
For a typical 500 sq ft garden. Serious collectors: consider a 2,000 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
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 15.3 inches of rain per year
- A 1,000 sq ft roof can collect roughly 7,625 gallons annually
- Rainwater harvesting is fully legal in your state
- In your dry climate, every drop counts — consider a larger cistern system
- Position collection tanks in shade to reduce evaporation and algae growth
Soil & Growing Conditions in Caribou County
Soil Type
Loam
Soil pH 6.8–8.1 · Well Drained drainage
Good candidate for raised beds to maximise drainage and extend the season.
Watering Needs
Drought stress: 7.5/10
High drought stress. Consistent irrigation is essential — consider drip systems, heavy mulch, and drought-tolerant varieties.
Season Tips
109-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 Caribou County
96 vegetables that grow well in Zone 4b with planting dates for Caribou County.
Show all 96 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | Apr 18 | Jun 13 | Jun 20 | Sep 12 – Oct 17 | 80–100 |
| Amaranth | Mar 28 | Jun 13 | Jun 20 | Sep 19 – Nov 7 | 90–120 |
| Arugula | Apr 18 | May 23 | May 30 | Jul 4 – Sep 5 | 30–50 |
| Asparagus | — | — | Jun 13 | — | 730–1095 |
| Beets | — | May 23 | — | Jul 18 – Aug 15 | 50–70 |
| Belgian Endive | Apr 18 | May 23 | May 30 | Sep 19 – Oct 24 | 110–150 |
| Black Beans | — | Jun 13 | — | Sep 12 – Oct 31 | 90–120 |
| Bok Choy | Apr 18 | May 23 | May 30 | Jul 11 – Aug 15 | 40–60 |
| Broccoli | Apr 18 | May 23 | May 30 | Aug 1 – Sep 12 | 60–90 |
| Broccoli Rabe | Apr 18 | May 23 | May 30 | Jul 11 – Aug 15 | 40–60 |
| Brussels Sprouts | Apr 18 | May 23 | May 30 | Aug 29 – Oct 24 | 90–130 |
| Butternut Squash | Apr 18 | Jun 13 | Jun 20 | Sep 19 – Oct 24 | 85–110 |
| Cabbage | Apr 18 | May 23 | May 30 | Aug 1 – Sep 26 | 60–100 |
| Carrots | — | May 23 | — | Jul 25 – Aug 29 | 60–80 |
| Cauliflower | Apr 18 | May 23 | May 30 | Jul 25 – Sep 26 | 55–100 |
| Celeriac | Apr 18 | May 23 | May 30 | Sep 12 – Oct 17 | 100–120 |
| Celery | Apr 18 | May 23 | May 30 | Aug 22 – Oct 17 | 80–120 |
| Celtuce | Apr 18 | May 23 | May 30 | Aug 1 – Sep 12 | 60–90 |
| Chard | Apr 18 | May 23 | May 30 | Jul 25 – Sep 12 | 50–60 |
| Chickpeas | Apr 18 | May 23 | May 30 | Aug 22 – Oct 3 | 80–110 |
| Chicory | Apr 18 | May 23 | May 30 | Aug 1 – Sep 12 | 60–85 |
| Chinese Cabbage | Apr 18 | May 23 | May 30 | Jul 25 – Aug 22 | 50–70 |
| Christmas Lima Beans | Mar 28 | Jun 13 | Jun 20 | Sep 12 – Oct 17 | 80–100 |
| Collard Greens | Apr 18 | May 23 | May 30 | Jul 25 – Sep 26 | 55–75 |
| Corn | — | Jun 13 | — | Aug 15 – Oct 10 | 60–100 |
| Cress | Apr 18 | May 23 | May 30 | Jun 13 – Jul 4 | 14–21 |
| Crookneck Squash | Apr 18 | Jun 13 | Jun 20 | Aug 8 – Sep 5 | 45–60 |
| Crosne | — | May 23 | — | Oct 24 – Oct 17 | 150–200 |
| Cucumber | Apr 18 | Jun 13 | Jun 20 | Aug 15 – Oct 10 | 50–70 |
| Daikon | — | May 23 | — | Jul 18 – Aug 15 | 50–70 |
| Delicata Squash | Apr 18 | Jun 13 | Jun 20 | Sep 12 – Oct 17 | 80–100 |
| Edamame | — | Jun 13 | — | Aug 29 – Oct 10 | 75–100 |
| Endive | Apr 18 | May 23 | May 30 | Jul 18 – Aug 22 | 45–65 |
| Escarole | Apr 18 | May 23 | May 30 | Jul 25 – Aug 22 | 50–70 |
| Fava Beans | Apr 18 | May 23 | May 30 | Aug 15 – Sep 26 | 75–100 |
| Fennel | Mar 28 | Jun 13 | Jun 20 | Aug 22 – Oct 3 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Jun 13 | — | Aug 8 – Oct 3 | 50–65 |
| Horseradish | — | — | Jun 13 | Oct 17 – Nov 7 | 120–180 |
| Hubbard Squash | Apr 18 | Jun 13 | Jun 20 | Oct 3 – Nov 7 | 100–120 |
| Kabocha | Apr 18 | Jun 13 | Jun 20 | Sep 19 – Oct 17 | 85–100 |
| Kai Lan | Apr 18 | May 23 | May 30 | Jul 18 – Aug 15 | 45–60 |
| Kale | Apr 18 | May 23 | May 30 | Jul 25 – Sep 19 | 50–70 |
| Kidney Beans | — | Jun 13 | — | Sep 12 – Oct 17 | 85–110 |
| Kohlrabi | Apr 18 | May 23 | May 30 | Jul 18 – Aug 22 | 45–65 |
| Komatsuna | Apr 18 | May 23 | May 30 | Jul 4 – Aug 8 | 35–50 |
| Leeks | Apr 18 | May 23 | May 30 | Aug 29 – Oct 24 | 90–150 |
| Lentils | Apr 18 | May 23 | May 30 | Aug 22 – Oct 3 | 80–110 |
| Lettuce | Apr 18 | May 23 | May 30 | Jul 4 – Sep 12 | 30–60 |
| Lima Beans | — | Jun 13 | — | Aug 15 – Sep 26 | 60–90 |
| Mache | Apr 18 | May 23 | May 30 | Jul 11 – Aug 15 | 40–60 |
| Melon | Apr 18 | Jun 13 | Jun 20 | Aug 29 – Oct 17 | 70–100 |
| Microgreens | Apr 18 | May 23 | May 30 | Jun 6 – Jul 4 | 7–21 |
| Mitsuba | Apr 18 | May 23 | May 23 | Jul 18 – Sep 12 | 50–70 |
| Mizuna | Apr 18 | May 23 | May 30 | Jul 4 – Aug 1 | 30–45 |
| Mustard Greens | Apr 18 | May 23 | May 30 | Jul 4 – Sep 5 | 30–50 |
| Napa Cabbage | Apr 18 | May 23 | May 30 | Jul 25 – Aug 29 | 55–75 |
| Onion | Apr 18 | May 23 | May 30 | Aug 29 – Oct 17 | 90–120 |
| Pac Choi | Apr 18 | May 23 | May 30 | Jul 11 – Aug 8 | 40–55 |
| Parsnip | — | May 23 | — | Sep 5 – Oct 17 | 100–130 |
| Patty Pan Squash | Apr 18 | Jun 13 | Jun 20 | Aug 8 – Sep 5 | 45–60 |
| Peas | Apr 18 | May 23 | May 30 | Jul 25 – Sep 19 | 55–70 |
| Peppers | Mar 14 | Jun 13 | Jun 20 | Aug 22 – Oct 31 | 60–90 |
| Pole Beans | Mar 28 | Jun 13 | Jun 20 | Aug 15 – Oct 10 | 55–70 |
| Potatoes | Mar 28 | Jun 13 | Jun 20 | Aug 29 – Nov 7 | 70–120 |
| Pumpkin | Apr 18 | Jun 13 | Jun 20 | Sep 19 – Nov 7 | 85–120 |
| Purslane | Apr 18 | May 23 | May 30 | Jul 11 – Aug 15 | 40–60 |
| Radicchio | Apr 18 | May 23 | May 30 | Aug 1 – Sep 5 | 60–80 |
| Radish | — | May 23 | — | Jun 20 – Jul 11 | 22–35 |
| Rhubarb | — | — | Jun 27 | — | 365–730 |
| Romanesco | Apr 18 | May 23 | May 30 | Aug 15 – Sep 26 | 75–100 |
| Rutabaga | — | May 23 | — | Aug 15 – Sep 19 | 80–100 |
| Salsify | — | May 23 | — | Sep 5 – Oct 17 | 100–130 |
| Savoy Cabbage | Apr 18 | May 23 | May 30 | Aug 8 – Oct 3 | 70–110 |
| Scallions | Apr 18 | May 23 | May 30 | Jul 25 – Aug 22 | 50–70 |
| Scarlet Runner Beans | Mar 28 | Jun 13 | Jun 20 | Aug 22 – Sep 26 | 60–80 |
| Shallot | Apr 18 | May 23 | May 30 | Aug 29 – Oct 17 | 90–120 |
| Shiso | Apr 4 | Jun 6 | Jun 20 | Aug 15 – Oct 10 | 50–70 |
| Snap Peas | Mar 28 | Jun 13 | Jun 20 | Aug 15 – Oct 10 | 55–70 |
| Snow Peas | Apr 18 | May 23 | May 30 | Jul 25 – Sep 19 | 50–65 |
| Soybeans | — | Jun 13 | — | Sep 5 – Oct 31 | 80–120 |
| Spaghetti Squash | Apr 18 | Jun 13 | Jun 20 | Sep 19 – Oct 17 | 85–100 |
| Spinach | Apr 18 | May 23 | May 30 | Jul 4 – Sep 5 | 35–50 |
| Squash (Summer) | Apr 18 | Jun 13 | Jun 20 | Aug 8 – Oct 10 | 45–65 |
| Squash (Winter) | Apr 18 | Jun 13 | Jun 20 | Sep 12 – Nov 7 | 80–120 |
| Sunchoke | — | — | Jun 13 | Oct 3 – Nov 7 | 110–150 |
| Sunflower | Mar 28 | Jun 13 | Jun 20 | Aug 29 – Oct 17 | 70–100 |
| Sweet Corn | — | Jun 13 | — | Aug 15 – Sep 26 | 60–90 |
| Tatsoi | Apr 18 | May 23 | May 30 | Jul 4 – Aug 8 | 35–50 |
| Tomatillo | Mar 28 | Jun 13 | Jun 20 | Aug 22 – Oct 31 | 60–85 |
| Tomatoes | Mar 28 | Jun 13 | Jun 20 | Aug 22 – Oct 31 | 60–85 |
| Turnip | — | May 23 | — | Jul 4 – Aug 8 | 40–60 |
| Watercress | Apr 18 | May 23 | May 30 | Jul 11 – Aug 15 | 40–60 |
| Watermelon | Apr 18 | Jun 13 | Jun 20 | Aug 29 – Oct 17 | 70–100 |
| Wax Beans | — | Jun 13 | — | Aug 8 – Oct 3 | 50–65 |
| Zucchini | Apr 18 | Jun 13 | Jun 20 | Aug 8 – Oct 3 | 45–60 |
🍓 Fruits to Grow in Caribou County
22 fruits that grow well in Zone 4b with planting dates for Caribou County.
Show all 22 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jun 27 | Sep 26 – Nov 21 | 90–180 |
| Aronia | — | — | Jun 27 | — | 730–1095 |
| Blueberries | — | — | Jun 27 | — | 730–1095 |
| Cantaloupe | — | — | Jun 27 | Sep 5 – Oct 10 | 70–90 |
| Cranberries | — | — | Jun 27 | — | 730–1095 |
| Currants | — | — | Jun 27 | — | 730–1095 |
| Elderberries | — | — | Jun 27 | — | 730–1095 |
| Goji Berries | — | — | Jun 27 | — | 730–1095 |
| Gooseberries | — | — | Jun 27 | — | 730–1095 |
| Grapes | — | — | Jun 27 | — | 730–1095 |
| Ground Cherry | — | — | Jun 27 | Sep 5 – Oct 31 | 65–80 |
| Hardy Kiwi | — | — | Jun 27 | — | 1095–1825 |
| Haskaps | — | — | Jun 27 | — | 730–1095 |
| Honeydew | — | — | Jun 27 | Sep 19 – Oct 31 | 80–110 |
| Jostaberry | — | — | Jun 27 | — | 730–1095 |
| Lingonberries | — | — | Jun 27 | — | 730–1095 |
| Medlar | — | — | Jun 27 | — | 1095–1825 |
| Mulberries | — | — | Jun 27 | — | 730–1825 |
| Persimmon | — | — | Jun 27 | — | 1095–2555 |
| Raspberries | — | — | Jun 27 | — | 365–730 |
| Serviceberries | — | — | Jun 27 | — | 730–1095 |
| Strawberries | — | — | Jun 27 | Sep 26 – Nov 21 | 90–365 |
🌿 Herbs to Grow in Caribou County
32 herbs that grow well in Zone 4b with planting dates for Caribou County.
Show all 32 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | Apr 18 | May 23 | May 23 | — | 365–730 |
| Anise | Apr 18 | May 23 | May 23 | Aug 22 – Oct 17 | 90–120 |
| Basil | Apr 4 | Jun 6 | Jun 20 | Aug 15 – Oct 17 | 50–75 |
| Bee Balm | — | — | Jun 6 | Sep 5 – Oct 31 | 90–120 |
| Borage | Apr 18 | May 23 | May 23 | Jul 18 – Sep 5 | 50–60 |
| Caraway | Apr 18 | May 23 | May 23 | — | 365–450 |
| Catnip | — | — | Jun 6 | Aug 8 – Oct 10 | 60–80 |
| Chamomile | Apr 18 | May 23 | May 23 | Jul 25 – Oct 3 | 60–90 |
| Chervil | Apr 18 | May 23 | May 23 | Jul 4 – Sep 5 | 40–60 |
| Chives | — | — | Jun 6 | Aug 8 – Oct 17 | 60–90 |
| Cilantro | Apr 18 | May 23 | May 23 | Jul 4 – Sep 5 | 40–60 |
| Comfrey | — | — | Jun 6 | Aug 8 – Oct 17 | 60–90 |
| Dill | Apr 18 | May 23 | May 23 | Jul 4 – Sep 5 | 40–60 |
| Echinacea | — | — | Jun 6 | Oct 10 – Oct 31 | 120–180 |
| Fennel (herb) | Apr 18 | May 23 | May 23 | Jul 25 – Oct 3 | 60–90 |
| Garlic Chives | — | — | Jun 6 | Aug 8 – Oct 17 | 60–90 |
| Horehound | — | — | Jun 6 | Aug 22 – Oct 17 | 75–90 |
| Hyssop | — | — | Jun 6 | Aug 15 – Oct 17 | 70–90 |
| Lemon Balm | — | — | Jun 6 | Aug 8 – Sep 26 | 60–70 |
| Lovage | — | — | Jun 6 | Aug 15 – Oct 17 | 70–90 |
| Mint | — | — | Jun 6 | Aug 8 – Oct 17 | 60–90 |
| Oregano | — | — | Jun 6 | Aug 8 – Oct 17 | 60–90 |
| Parsley | Apr 18 | May 23 | May 23 | Jul 25 – Sep 26 | 60–80 |
| Rue | — | — | Jun 6 | Aug 15 – Oct 17 | 70–90 |
| Sage | — | — | Jun 6 | Aug 22 – Oct 17 | 75–90 |
| Savory | — | — | Jun 6 | Aug 1 – Sep 26 | 50–70 |
| Sorrel | Apr 18 | May 23 | May 23 | Jul 4 – Sep 5 | 40–60 |
| Tarragon | — | — | Jun 6 | Aug 8 – Oct 17 | 60–90 |
| Thai Basil | Apr 4 | Jun 6 | Jun 20 | Aug 15 – Oct 17 | 50–75 |
| Thyme | — | — | Jun 6 | Aug 15 – Oct 17 | 70–90 |
| Valerian | — | — | Jun 6 | Oct 10 – Oct 31 | 120–180 |
| Yarrow | — | — | Jun 6 | Sep 5 – Oct 31 | 90–120 |
Monthly Planting Guide for Caribou County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Caribou County.
Frequently Asked Questions
What planting zone is Caribou County, ID?
Caribou County is in USDA Hardiness Zone 4b. 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 Caribou County, ID?
Based on 31 years of NOAA weather station data, the median last spring frost in Caribou County falls around May 30. In 8 out of 10 years, last frost lands between May 8 and June 17 — a 40-day window of variability. Use June 17 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Caribou County, ID?
The median first fall frost in Caribou County arrives around September 16. In cold years it can arrive as early as September 2; in mild years as late as October 9. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Caribou County?
Caribou County has a frost-free growing season of approximately 109 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 1.97 days per decade.
What is the soil like in Caribou County for gardening?
Caribou County has predominantly Loam soil with a pH range of 6.8–8.1 and Well Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Caribou County?
Caribou County has commercial agriculture that includes Potatoes, Hay, Wheat, Sugar Beets. These crops reflect the local climate and soil conditions — what succeeds commercially often translates well to home gardens in the same area.
Is Caribou County a good location for home gardening?
Caribou County scores 30/100 (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 Caribou County gardeners in Zone 4b 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.
