Summit County, CO — Planting Guide
Summit County is in USDA Zone 4a. The average last spring frost is June 16 and the first fall frost is September 4, giving you a growing season of approximately 80 days.
At an elevation of 7,005 ft, Summit County receives approximately 17.5 in of rainfall annually. Summer highs average 81°F with winter lows around 6°F. The predominant soil type is Loam.
Based on 31 years of NOAA climate station data, the last frost date here varies by 29 days year to year — ranging from May 28 in warm years to June 26 in cold years. The growing season is trending longer by about 1.67 days per decade. Summit County scores 33/100 (Challenging) on the Microclimate Index.
🌡️ Zone
4a (-30°F to -25°F min)
❄️ Last Frost
June 16
🍂 First Frost
September 4
📅 Growing Season
80 days
⛰️ Elevation
7,005 ft
🌧️ Annual Rainfall
17.5 in
Monthly Watering Calendar
When you'll need to water your garden — based on average monthly rainfall vs. the ~1 inch/week most gardens need.
View detailed monthly data
| Month | Avg Rainfall | Rainy Days | Extra Water Needed | Watering Effort |
|---|---|---|---|---|
| Jan | 1.4 in | 6 days | — | None |
| Feb | 1.1 in | 5 days | — | None |
| Mar | 1.6 in | 9 days | — | None |
| Apr | 1.7 in | 8 days | 2.6 in | High |
| May | 1.8 in | 7 days | 2.5 in | High |
| Jun | 1.3 in | 5 days | 3 in | High |
| Jul | 1.5 in | 5 days | 2.8 in | High |
| Aug | 1.9 in | 7 days | 2.4 in | High |
| Sep | 1.3 in | 5 days | 3 in | High |
| Oct | 1.6 in | 5 days | 2.7 in | High |
| Nov | 1.2 in | 5 days | — | None |
| Dec | 1.2 in | 7 days | — | None |
Annual total: 17.6 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.
Summit County Soil Profile
Soil Type
Loam
Soil pH
6.8-8
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 26 | Sep 20 | 86 days |
| Cautious | Jun 22 | Sep 10 | 80 days |
| Average year | Jun 16 | Sep 4 | 80 days |
| Optimistic | Jun 10 | Aug 27 | 78 days |
| Aggressive (risky) | May 28 | Aug 15 | 79 days |
Not very — frost dates can vary by ±29 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 1.7 days per decade). Spring is arriving earlier than it used to. Good news for gardeners.
Gardening Difficulty Score
Summit County has challenging growing conditions. Season extension and careful variety selection are essential.
Local Gardening Help in Summit 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 Summit County's climate and soil.
County Extension Office
Summit County Colorado State University Extension Extension Office
Phone: 970-491-6281
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 Summit County
Finding local nurseries & garden centers in Summit County
Why Buy Local
Local nurseries carry plants that are proven to grow in your area. Staff can give you advice specific to Summit 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 Summit County CO" or "garden center Summit 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 Summit County CO" or check your extension office and local parks department. Facebook groups like "Summit County Gardeners" or "Colorado 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
14.8 hours
Summer solstice daylight
Shortest Day
9.2 hours
Winter solstice daylight
Peak Sun Hours
11.1 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 | 9.5 hr | 5.5 hr | Short day |
| February | 10.5 hr | 6.1 hr | Short day |
| March | 11.7 hr | 7.1 hr | Short day |
| April | 13.1 hr | 7.2 hr | Neutral |
| May | 14.2 hr | 8.8 hr | Long day |
| June | 14.8 hr | 11.1 hr | Long day |
| July | 14.5 hr | 9.8 hr | Long day |
| August | 13.6 hr | 9.4 hr | Neutral |
| September | 12.2 hr | 8.1 hr | Neutral |
| October | 10.9 hr | 6.9 hr | Short day |
| November | 9.8 hr | 5.8 hr | Short day |
| December | 9.2 hr | 5.1 hr | Short day |
Peak sun hours factor in typical cloud cover — use these for solar panel and shade-planning calculations.
Soil Temperature & Composting Calendar
Monthly soil temps tell you when to plant warm-season crops, and when your compost pile is actively working.
Plant Warm Crops When
Soil reaches 60°F+
Soil 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 | -4°F | 3°F | ❄️ Dormant | ~36 weeks |
| Feb | -3°F | 1°F | ❄️ Dormant | ~36 weeks |
| Mar | 6°F | 10°F | ❄️ Dormant | ~36 weeks |
| Apr | 20°F | 20°F | ❄️ Dormant | ~36 weeks |
| May | 32°F | 30°F | ❄️ Dormant | ~36 weeks |
| Jun | 45°F | 40°F | 🐢 Slow | ~24 weeks |
| Jul | 51°F | 45°F | ♻️ Active | ~14 weeks |
| Aug | 54°F | 50°F | ♻️ Active | ~14 weeks |
| Sep | 44°F | 43°F | 🐢 Slow | ~24 weeks |
| Oct | 33°F | 34°F | ❄️ Dormant | ~36 weeks |
| Nov | 16°F | 23°F | ❄️ Dormant | ~36 weeks |
| Dec | 4°F | 11°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 Summit 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 | Moderate | Jun, Jul |
| Flea beetles | Moderate | 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 Summit 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 16 | May 26 | — | Deep taproot breaks compaction, excellent for clay soils |
| Hairy vetch | Jun 10 | Jun 2 | ✓ Yes | Excellent nitrogen fixer, good for depleted soils |
| Oats | Jul 26 | May 26 | — | Quick biomass, winterkills in cold zones — no spring tillage needed |
| Winter rye | Jun 12 | Jun 2 | — | Suppresses weeds, prevents erosion, breaks up compacted soil |
| Winter wheat | May 29 | Jun 2 | — | 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 16 | Jun 26 | — | Rapid growth, attracts pollinators, suppresses weeds |
| White clover | May 20 | Jun 26 | ✓ 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 1 | Aug 14 | — | 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: 17 mph Summer: 11 mph
Fall: 12 mph Winter: 14 mph
Prevailing wind: W. Windy area — plant a windbreak hedge on the W side of your garden.
Windbreak Benefit
7/10
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 2,839 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
8,771 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 1,750 gal tank.
Legal Status
Limited
Your state has quantity limits on rainwater collection — check local regulations before installing large systems.
Best Collection Months
Mar, Apr, May, 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 17.6 inches of rain per year
- A 1,000 sq ft roof can collect roughly 8,771 gallons annually
- Check CO state regulations — rainwater harvesting has quantity limits
- 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 Summit County
Soil Type
Loam
Soil pH 6.8–8 · Excessively 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
80-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 Summit County
96 vegetables that grow well in Zone 4a with planting dates for Summit County.
Show all 96 vegetables with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Acorn Squash | May 5 | Jun 30 | Jul 7 | Sep 29 – Nov 3 | 80–100 |
| Amaranth | Apr 14 | Jun 30 | Jul 7 | Oct 6 – Nov 24 | 90–120 |
| Arugula | May 5 | Jun 9 | Jun 16 | Jul 21 – Sep 22 | 30–50 |
| Asparagus | — | — | Jun 30 | — | 730–1095 |
| Beets | — | Jun 9 | — | Aug 4 – Sep 1 | 50–70 |
| Belgian Endive | May 5 | Jun 9 | Jun 16 | Oct 6 – Nov 10 | 110–150 |
| Black Beans | — | Jun 30 | — | Sep 29 – Nov 17 | 90–120 |
| Bok Choy | May 5 | Jun 9 | Jun 16 | Jul 28 – Sep 1 | 40–60 |
| Broccoli | May 5 | Jun 9 | Jun 16 | Aug 18 – Sep 29 | 60–90 |
| Broccoli Rabe | May 5 | Jun 9 | Jun 16 | Jul 28 – Sep 1 | 40–60 |
| Brussels Sprouts | May 5 | Jun 9 | Jun 16 | Sep 15 – Nov 10 | 90–130 |
| Butternut Squash | May 5 | Jun 30 | Jul 7 | Oct 6 – Nov 10 | 85–110 |
| Cabbage | May 5 | Jun 9 | Jun 16 | Aug 18 – Oct 13 | 60–100 |
| Carrots | — | Jun 9 | — | Aug 11 – Sep 15 | 60–80 |
| Cauliflower | May 5 | Jun 9 | Jun 16 | Aug 11 – Oct 13 | 55–100 |
| Celeriac | May 5 | Jun 9 | Jun 16 | Sep 29 – Nov 3 | 100–120 |
| Celery | May 5 | Jun 9 | Jun 16 | Sep 8 – Nov 3 | 80–120 |
| Celtuce | May 5 | Jun 9 | Jun 16 | Aug 18 – Sep 29 | 60–90 |
| Chard | May 5 | Jun 9 | Jun 16 | Aug 11 – Sep 29 | 50–60 |
| Chickpeas | May 5 | Jun 9 | Jun 16 | Sep 8 – Oct 20 | 80–110 |
| Chicory | May 5 | Jun 9 | Jun 16 | Aug 18 – Sep 29 | 60–85 |
| Chinese Cabbage | May 5 | Jun 9 | Jun 16 | Aug 11 – Sep 8 | 50–70 |
| Christmas Lima Beans | Apr 14 | Jun 30 | Jul 7 | Sep 29 – Nov 3 | 80–100 |
| Collard Greens | May 5 | Jun 9 | Jun 16 | Aug 11 – Oct 13 | 55–75 |
| Corn | — | Jun 30 | — | Sep 1 – Oct 27 | 60–100 |
| Cress | May 5 | Jun 9 | Jun 16 | Jun 30 – Jul 21 | 14–21 |
| Crookneck Squash | May 5 | Jun 30 | Jul 7 | Aug 25 – Sep 22 | 45–60 |
| Crosne | — | Jun 9 | — | Nov 10 – Nov 3 | 150–200 |
| Cucumber | May 5 | Jun 30 | Jul 7 | Sep 1 – Oct 27 | 50–70 |
| Daikon | — | Jun 9 | — | Aug 4 – Sep 1 | 50–70 |
| Delicata Squash | May 5 | Jun 30 | Jul 7 | Sep 29 – Nov 3 | 80–100 |
| Edamame | — | Jun 30 | — | Sep 15 – Oct 27 | 75–100 |
| Endive | May 5 | Jun 9 | Jun 16 | Aug 4 – Sep 8 | 45–65 |
| Escarole | May 5 | Jun 9 | Jun 16 | Aug 11 – Sep 8 | 50–70 |
| Fava Beans | May 5 | Jun 9 | Jun 16 | Sep 1 – Oct 13 | 75–100 |
| Fennel | Apr 14 | Jun 30 | Jul 7 | Sep 8 – Oct 20 | 60–90 |
| Garlic | — | — | — | — | 90–240 |
| Green Beans | — | Jun 30 | — | Aug 25 – Oct 20 | 50–65 |
| Horseradish | — | — | Jun 30 | Nov 3 – Nov 24 | 120–180 |
| Hubbard Squash | May 5 | Jun 30 | Jul 7 | Oct 20 – Nov 24 | 100–120 |
| Kabocha | May 5 | Jun 30 | Jul 7 | Oct 6 – Nov 3 | 85–100 |
| Kai Lan | May 5 | Jun 9 | Jun 16 | Aug 4 – Sep 1 | 45–60 |
| Kale | May 5 | Jun 9 | Jun 16 | Aug 11 – Oct 6 | 50–70 |
| Kidney Beans | — | Jun 30 | — | Sep 29 – Nov 3 | 85–110 |
| Kohlrabi | May 5 | Jun 9 | Jun 16 | Aug 4 – Sep 8 | 45–65 |
| Komatsuna | May 5 | Jun 9 | Jun 16 | Jul 21 – Aug 25 | 35–50 |
| Leeks | May 5 | Jun 9 | Jun 16 | Sep 15 – Nov 10 | 90–150 |
| Lentils | May 5 | Jun 9 | Jun 16 | Sep 8 – Oct 20 | 80–110 |
| Lettuce | May 5 | Jun 9 | Jun 16 | Jul 21 – Sep 29 | 30–60 |
| Lima Beans | — | Jun 30 | — | Sep 1 – Oct 13 | 60–90 |
| Mache | May 5 | Jun 9 | Jun 16 | Jul 28 – Sep 1 | 40–60 |
| Melon | May 5 | Jun 30 | Jul 7 | Sep 15 – Nov 3 | 70–100 |
| Microgreens | May 5 | Jun 9 | Jun 16 | Jun 23 – Jul 21 | 7–21 |
| Mitsuba | May 5 | Jun 9 | Jun 9 | Aug 4 – Sep 29 | 50–70 |
| Mizuna | May 5 | Jun 9 | Jun 16 | Jul 21 – Aug 18 | 30–45 |
| Mustard Greens | May 5 | Jun 9 | Jun 16 | Jul 21 – Sep 22 | 30–50 |
| Napa Cabbage | May 5 | Jun 9 | Jun 16 | Aug 11 – Sep 15 | 55–75 |
| Onion | May 5 | Jun 9 | Jun 16 | Sep 15 – Nov 3 | 90–120 |
| Pac Choi | May 5 | Jun 9 | Jun 16 | Jul 28 – Aug 25 | 40–55 |
| Parsnip | — | Jun 9 | — | Sep 22 – Nov 3 | 100–130 |
| Patty Pan Squash | May 5 | Jun 30 | Jul 7 | Aug 25 – Sep 22 | 45–60 |
| Peas | May 5 | Jun 9 | Jun 16 | Aug 11 – Oct 6 | 55–70 |
| Peppers | Mar 31 | Jun 30 | Jul 7 | Sep 8 – Nov 17 | 60–90 |
| Pole Beans | Apr 14 | Jun 30 | Jul 7 | Sep 1 – Oct 27 | 55–70 |
| Potatoes | Apr 14 | Jun 30 | Jul 7 | Sep 15 – Nov 24 | 70–120 |
| Pumpkin | May 5 | Jun 30 | Jul 7 | Oct 6 – Nov 24 | 85–120 |
| Purslane | May 5 | Jun 9 | Jun 16 | Jul 28 – Sep 1 | 40–60 |
| Radicchio | May 5 | Jun 9 | Jun 16 | Aug 18 – Sep 22 | 60–80 |
| Radish | — | Jun 9 | — | Jul 7 – Jul 28 | 22–35 |
| Rhubarb | — | — | Jul 14 | — | 365–730 |
| Romanesco | May 5 | Jun 9 | Jun 16 | Sep 1 – Oct 13 | 75–100 |
| Rutabaga | — | Jun 9 | — | Sep 1 – Oct 6 | 80–100 |
| Salsify | — | Jun 9 | — | Sep 22 – Nov 3 | 100–130 |
| Savoy Cabbage | May 5 | Jun 9 | Jun 16 | Aug 25 – Oct 20 | 70–110 |
| Scallions | May 5 | Jun 9 | Jun 16 | Aug 11 – Sep 8 | 50–70 |
| Scarlet Runner Beans | Apr 14 | Jun 30 | Jul 7 | Sep 8 – Oct 13 | 60–80 |
| Shallot | May 5 | Jun 9 | Jun 16 | Sep 15 – Nov 3 | 90–120 |
| Shiso | Apr 21 | Jun 23 | Jul 7 | Sep 1 – Oct 27 | 50–70 |
| Snap Peas | Apr 14 | Jun 30 | Jul 7 | Sep 1 – Oct 27 | 55–70 |
| Snow Peas | May 5 | Jun 9 | Jun 16 | Aug 11 – Oct 6 | 50–65 |
| Soybeans | — | Jun 30 | — | Sep 22 – Nov 17 | 80–120 |
| Spaghetti Squash | May 5 | Jun 30 | Jul 7 | Oct 6 – Nov 3 | 85–100 |
| Spinach | May 5 | Jun 9 | Jun 16 | Jul 21 – Sep 22 | 35–50 |
| Squash (Summer) | May 5 | Jun 30 | Jul 7 | Aug 25 – Oct 27 | 45–65 |
| Squash (Winter) | May 5 | Jun 30 | Jul 7 | Sep 29 – Nov 24 | 80–120 |
| Sunchoke | — | — | Jun 30 | Oct 20 – Nov 24 | 110–150 |
| Sunflower | Apr 14 | Jun 30 | Jul 7 | Sep 15 – Nov 3 | 70–100 |
| Sweet Corn | — | Jun 30 | — | Sep 1 – Oct 13 | 60–90 |
| Tatsoi | May 5 | Jun 9 | Jun 16 | Jul 21 – Aug 25 | 35–50 |
| Tomatillo | Apr 14 | Jun 30 | Jul 7 | Sep 8 – Nov 17 | 60–85 |
| Tomatoes | Apr 14 | Jun 30 | Jul 7 | Sep 8 – Nov 17 | 60–85 |
| Turnip | — | Jun 9 | — | Jul 21 – Aug 25 | 40–60 |
| Watercress | May 5 | Jun 9 | Jun 16 | Jul 28 – Sep 1 | 40–60 |
| Watermelon | May 5 | Jun 30 | Jul 7 | Sep 15 – Nov 3 | 70–100 |
| Wax Beans | — | Jun 30 | — | Aug 25 – Oct 20 | 50–65 |
| Zucchini | May 5 | Jun 30 | Jul 7 | Aug 25 – Oct 20 | 45–60 |
🍓 Fruits to Grow in Summit County
22 fruits that grow well in Zone 4a with planting dates for Summit County.
Show all 22 fruits with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Alpine Strawberries | — | — | Jul 14 | Oct 13 – Dec 8 | 90–180 |
| Aronia | — | — | Jul 14 | — | 730–1095 |
| Blueberries | — | — | Jul 14 | — | 730–1095 |
| Cantaloupe | — | — | Jul 14 | Sep 22 – Oct 27 | 70–90 |
| Cranberries | — | — | Jul 14 | — | 730–1095 |
| Currants | — | — | Jul 14 | — | 730–1095 |
| Elderberries | — | — | Jul 14 | — | 730–1095 |
| Goji Berries | — | — | Jul 14 | — | 730–1095 |
| Gooseberries | — | — | Jul 14 | — | 730–1095 |
| Grapes | — | — | Jul 14 | — | 730–1095 |
| Ground Cherry | — | — | Jul 14 | Sep 22 – Nov 17 | 65–80 |
| Hardy Kiwi | — | — | Jul 14 | — | 1095–1825 |
| Haskaps | — | — | Jul 14 | — | 730–1095 |
| Honeydew | — | — | Jul 14 | Oct 6 – Nov 17 | 80–110 |
| Jostaberry | — | — | Jul 14 | — | 730–1095 |
| Lingonberries | — | — | Jul 14 | — | 730–1095 |
| Medlar | — | — | Jul 14 | — | 1095–1825 |
| Mulberries | — | — | Jul 14 | — | 730–1825 |
| Persimmon | — | — | Jul 14 | — | 1095–2555 |
| Raspberries | — | — | Jul 14 | — | 365–730 |
| Serviceberries | — | — | Jul 14 | — | 730–1095 |
| Strawberries | — | — | Jul 14 | Oct 13 – Dec 8 | 90–365 |
🌿 Herbs to Grow in Summit County
32 herbs that grow well in Zone 4a with planting dates for Summit County.
Show all 32 herbs with planting dates
| Plant | Start Indoors | Direct Sow | Transplant | Harvest | Days to Maturity |
|---|---|---|---|---|---|
| Angelica | May 5 | Jun 9 | Jun 9 | — | 365–730 |
| Anise | May 5 | Jun 9 | Jun 9 | Sep 8 – Nov 3 | 90–120 |
| Basil | Apr 21 | Jun 23 | Jul 7 | Sep 1 – Nov 3 | 50–75 |
| Bee Balm | — | — | Jun 23 | Sep 22 – Nov 17 | 90–120 |
| Borage | May 5 | Jun 9 | Jun 9 | Aug 4 – Sep 22 | 50–60 |
| Caraway | May 5 | Jun 9 | Jun 9 | — | 365–450 |
| Catnip | — | — | Jun 23 | Aug 25 – Oct 27 | 60–80 |
| Chamomile | May 5 | Jun 9 | Jun 9 | Aug 11 – Oct 20 | 60–90 |
| Chervil | May 5 | Jun 9 | Jun 9 | Jul 21 – Sep 22 | 40–60 |
| Chives | — | — | Jun 23 | Aug 25 – Nov 3 | 60–90 |
| Cilantro | May 5 | Jun 9 | Jun 9 | Jul 21 – Sep 22 | 40–60 |
| Comfrey | — | — | Jun 23 | Aug 25 – Nov 3 | 60–90 |
| Dill | May 5 | Jun 9 | Jun 9 | Jul 21 – Sep 22 | 40–60 |
| Echinacea | — | — | Jun 23 | Oct 27 – Nov 17 | 120–180 |
| Fennel (herb) | May 5 | Jun 9 | Jun 9 | Aug 11 – Oct 20 | 60–90 |
| Garlic Chives | — | — | Jun 23 | Aug 25 – Nov 3 | 60–90 |
| Horehound | — | — | Jun 23 | Sep 8 – Nov 3 | 75–90 |
| Hyssop | — | — | Jun 23 | Sep 1 – Nov 3 | 70–90 |
| Lemon Balm | — | — | Jun 23 | Aug 25 – Oct 13 | 60–70 |
| Lovage | — | — | Jun 23 | Sep 1 – Nov 3 | 70–90 |
| Mint | — | — | Jun 23 | Aug 25 – Nov 3 | 60–90 |
| Oregano | — | — | Jun 23 | Aug 25 – Nov 3 | 60–90 |
| Parsley | May 5 | Jun 9 | Jun 9 | Aug 11 – Oct 13 | 60–80 |
| Rue | — | — | Jun 23 | Sep 1 – Nov 3 | 70–90 |
| Sage | — | — | Jun 23 | Sep 8 – Nov 3 | 75–90 |
| Savory | — | — | Jun 23 | Aug 18 – Oct 13 | 50–70 |
| Sorrel | May 5 | Jun 9 | Jun 9 | Jul 21 – Sep 22 | 40–60 |
| Tarragon | — | — | Jun 23 | Aug 25 – Nov 3 | 60–90 |
| Thai Basil | Apr 21 | Jun 23 | Jul 7 | Sep 1 – Nov 3 | 50–75 |
| Thyme | — | — | Jun 23 | Sep 1 – Nov 3 | 70–90 |
| Valerian | — | — | Jun 23 | Oct 27 – Nov 17 | 120–180 |
| Yarrow | — | — | Jun 23 | Sep 22 – Nov 17 | 90–120 |
Monthly Planting Guide for Summit County
Gardening Guides & Resources
Helpful guides from The Ultimate Homestead to improve your garden in Summit County.
Frequently Asked Questions
What planting zone is Summit County, CO?
Summit 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 Summit County, CO?
Based on 31 years of NOAA weather station data, the median last spring frost in Summit County falls around June 16. In 8 out of 10 years, last frost lands between May 28 and June 26 — a 29-day window of variability. Use June 26 as your conservative safe-to-plant date for frost-sensitive crops.
When is the first fall frost in Summit County, CO?
The median first fall frost in Summit County arrives around September 4. In cold years it can arrive as early as August 15; in mild years as late as September 20. Harvest or protect frost-sensitive crops — tomatoes, peppers, basil, squash — before this date.
How long is the growing season in Summit County?
Summit County has a frost-free growing season of approximately 80 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 1.67 days per decade.
What is the soil like in Summit County for gardening?
Summit County has predominantly Loam soil with a pH range of 6.8–8 and Excessively Drained drainage. Most vegetables and herbs grow well with standard composting and seasonal soil amendment.
What is grown commercially in Summit County?
Summit County has commercial agriculture that includes Cattle, Wheat, 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 Summit County a good location for home gardening?
Summit County scores 33/100 (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 Summit 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.
