Local planting guide · Mountain West
zip 80208
Denver is in USDA hardiness zone 6a, with average winter lows of -10°F to -5°F. The local growing season runs roughly 05/04 through 10/08 (~156 days). This zip falls within the Mountain West growing region.
- USDA zone
- 6a -10°F to -5°F
- Last spring frost
- 05/04
- First fall frost
- 10/08
- Growing season
- 156 days
- Compatible crops
- 87
- Growing region
- Mountain West
Right now in Denver
Week 18 priorities
On the docket: transplant out after last frost · direct sow after last frost. See the full calendar →
Gardening in Denver
Denver sits at the edge of USDA zone 6a, where winter lows average -10 to -5°F. The defining characteristics are not cold alone but the combination of cold, altitude, and aridity. Summers are intense: long days and thin atmosphere mean strong UV and rapid soil drying. The 156-day growing season from May 4 (last spring frost) to October 8 (first fall frost) is workable for most fruits, though the spring frost date is often deceptive. Late freezes in May are common after warm early spring weather triggers bud break. Stone fruits thrive here. Apples, pears, peaches, European and Japanese plums, both sweet and sour cherries, and American persimmons all grow reliably in Denver, with the caveat that variety selection matters. The same trees might fail in zone 6a locations with higher humidity and different frost timing. Denver's dry climate is an advantage for disease prevention (fungal issues that plague humid regions are less common), but it creates its own pressures: intense sun, low-humidity stress, and the constant threat of afternoon hail during the growing season.
Regional context · Mountain West
What the Mountain West brings to Denver
High elevation, dry air, intense sun, big diurnal swings. Short cool growing season at altitude; longer hot one in valleys. Strong fruit production in irrigated river corridors.
Common challenges
Issues that most often defeat home gardeners in zone 6a, drawn from the broader USDA zone profile.
- ▸ Brown rot in stone fruit
- ▸ Japanese beetles
- ▸ Spring frost damage to peach buds
What defeats new gardeners in Denver
Late spring freezes are the most consistent challenge. A warm March can trigger bud break, followed by hard freezes in late April or early May. The May 4 average last frost date is a statistical midpoint, not a guarantee. Fruit buds often rupture before flowers form, leaving the tree leafed out but fruitless. A second major problem is hail. Denver's location on the plains means severe hail storms strike regularly from May through August, sometimes shredding foliage, stripping fruit, or killing thin-barked young trees outright. The third issue is water. Denver's semi-arid climate means insufficient rainfall for most fruit trees during critical fruit development periods. Supplemental irrigation is mandatory, though restrictions are common during drought years. Trees must be selected and pruned for resilience to both moisture stress and occasional overwatering during wet years.
Crops that grow in Denver
87 crops from our catalog match zone 6a, grouped by type.
Tree fruit
12 crops
zone 6a Apple
Malus domestica
zones 3a–9a
zone 6a Pear
Pyrus communis
zones 4a–8b
zone 6a Peach
Prunus persica
zones 5a–9a
zone 6a European Plum
Prunus domestica
zones 4a–8a
zone 6a Japanese Plum
Prunus salicina
zones 5b–9a
zone 6a Sweet Cherry
Prunus avium
zones 5a–8a
zone 6a Sour Cherry
Prunus cerasus
zones 4a–7b
zone 6a American Persimmon
Diospyros virginiana
zones 4b–9a
Berries
20 crops
zone 6a Highbush Blueberry
Vaccinium corymbosum
zones 4a–7b
zone 6a Lowbush Blueberry
Vaccinium angustifolium
zones 3a–6b
zone 6a Red Raspberry
Rubus idaeus
zones 3b–8a
zone 6a Black Raspberry
Rubus occidentalis
zones 4a–8a
zone 6a Yellow Raspberry
Rubus idaeus
zones 3b–8a
zone 6a Blackberry
Rubus subgenus Rubus
zones 5a–9a
zone 6a June-Bearing Strawberry
Fragaria x ananassa
zones 3a–8b
zone 6a Everbearing Strawberry
Fragaria x ananassa
zones 3b–9a
Nuts
6 crops
Vegetables
40 crops
zone 6a Tomato
Solanum lycopersicum
zones 3a–10b
zone 6a Sweet Pepper
Capsicum annuum
zones 4a–10b
zone 6a Hot Pepper
Capsicum species
zones 4a–10b
zone 6a Eggplant
Solanum melongena
zones 5a–10b
zone 6a Potato
Solanum tuberosum
zones 3a–9a
zone 6a Cabbage
Brassica oleracea var. capitata
zones 3a–9b
zone 6a Broccoli
Brassica oleracea var. italica
zones 3a–9a
zone 6a Cauliflower
Brassica oleracea var. botrytis
zones 3b–9a
Herbs
9 crops
zone 6a Basil
Ocimum basilicum
zones 4a–10b
zone 6a Parsley
Petroselinum crispum
zones 3b–9b
zone 6a Cilantro / Coriander
Coriandrum sativum
zones 3b–9b
zone 6a Dill
Anethum graveolens
zones 3b–9a
zone 6a Oregano
Origanum vulgare
zones 4a–9b
zone 6a Thyme
Thymus vulgaris
zones 4a–9a
zone 6a Sage
Salvia officinalis
zones 4a–9a
zone 6a Mint
Mentha species
zones 3b–9b
Plan the year
Planting calendar for Denver
Year-view of seed starting, transplanting, planting, pruning, fertilizing, harvest, and pest-watch windows tuned to Denver's local frost dates.
Week ? · loading
This week in Denver, CO (zone 6a)
Quiet week in Denver, CO (zone 6a). this week is a good time to step back and plan ahead.
Nothing critical on the calendar this week.
434 bars · 87 crops
Calendar logic combines NOAA frost normals with crop-specific timing data. Local microclimate and weather always overrules the calendar; use this as a starting point.
Top pests for zone 6a
Ranked by how many crops in your zone they affect. Click through for IPM controls and signs to watch for.
Multiple species (Aphididae)
Small soft-bodied sap-sucking insects that reproduce explosively in spring. Excrete honeydew that supports sooty mold and attracts ants. Transmit viral diseases.
Odocoileus species
Whitetail and mule deer browse can devastate orchards and gardens, particularly in winter when food is scarce. Antler rub on young trunks kills saplings outright.
Multiple species
Robins, catbirds, mockingbirds, starlings, cedar waxwings and other songbirds can strip ripening berry and fruit crops in days. Crows and blackbirds also damage fresh sweet corn ears in milk stage. The single biggest yield-loss factor in unprotected home plantings.
Sylvilagus and Lepus species
Cottontails and jackrabbits strip bark from young fruit trees in winter and graze tender garden vegetables year-round, especially seedlings.
Popillia japonica
Defoliating beetle introduced to North America in 1916. Skeletonizes leaves of many fruit trees, berry canes, and pecan.
Multiple species (Chrysomelidae)
Tiny black or bronze jumping beetles that put hundreds of small holes in seedling leaves. Most damaging on direct-seeded brassicas and young eggplant.
Tetranychus urticae
Tiny mite that feeds on leaf undersides, causing stippling and webbing during hot dry weather.
Microtus species
Field voles and meadow voles girdle young fruit-tree trunks under snow cover during winter and chew root crops. The leading cause of mysterious orchard losses.
Top diseases for zone 6a
Ranked by how many crops in your zone they affect. Click through for symptoms, controls, and resistant varieties.
Botrytis cinerea
Ubiquitous fungal disease that causes fruit rot during cool wet weather, often the dominant berry disease in humid regions.
Pseudoperonospora cubensis (cucurbits) and others
Water mold (oomycete, not a true fungus) that thrives in cool damp conditions. Spreads rapidly through cucurbit and brassica plantings on wind-borne spores.
Pythium and Rhizoctonia species
Soil-borne complex of water molds and fungi that kill seedlings before or shortly after emergence. The single most common cause of seed-starting failures.
Cucumber mosaic virus, Tobacco mosaic virus, and others
Family of plant viruses producing mottled yellow-and-green leaf patterns. Vectored primarily by aphids; some are seed-transmitted or spread by handling tools and tobacco products.
Agrobacterium tumefaciens
Soil-borne bacterium that enters plants through wounds and induces tumor-like galls on roots, crown, and lower stems. Galls reduce vigor and shorten plant lifespan; on Rubus the disease is often fatal.
Fusarium oxysporum
Soil-borne fungal disease that plugs vascular tissue and kills affected plants. Persists in soil for many years; impossible to eliminate once established.
Sclerotium rolfsii
Soil-borne fungal disease most damaging in warm humid Southern conditions. White mycelial fans and small mustard-seed-sized sclerotia at the soil line are diagnostic.
Plasmodiophora brassicae
Soil-borne disease causing characteristic distorted club-shaped roots on brassicas. Persists in soil for 10-20 years; the dominant brassica pathogen in acidic poorly-drained soils.
Companion planting suggestions
Beneficial pairings drawn from companion data, filtered to crops that grow in zone 6a.
- Peach + Garlic
Garlic planted around peach trees suppresses peach borer and provides general fungal-pressure reduction.
- European Plum + Garlic
Garlic discourages plum curculio and provides general antifungal benefit beneath stone fruit.
- American Persimmon + Pawpaw
Both natives thrive in similar soils and contribute to a polyculture that supports native pollinators and fauna.
- Jujube + Thyme
Thyme groundcover suits jujube's low-water profile and deters cabbage moth and aphid populations.
- Apricot + Basil
Basil's volatile oils discourage stone-fruit pests and support pollinator visits.
- Highbush Blueberry + Thyme
Creeping thyme thrives in the acidic mulched conditions blueberries require and attracts pollinators during bloom.
Soil types reference
Soil texture and pH decide what grows easily on your specific lot. Find the closest match below for crop recommendations and amendment guidance.
Practical tips for Denver
Select late-blooming varieties that avoid the May frost window. Japanese plums bloom later than European plums, making them more reliable. Some apple cultivars are specifically bred for late-frost regions and are much safer choices for Denver gardens. This single variety selection prevents the majority of bud-loss years and improves overall reliability. Second, install drip irrigation on a timer to provide consistent water during the critical fruit development period from June through early August. The short growing season and low rainfall make consistent water through June and July essential for quality fruit development. Hand-watering is unreliable in Denver's dry air, which dries soil rapidly and wastes water to evaporation. Third, mulch heavily with wood chips to moderate soil temperature swings and retain moisture in the sandy, dry soil. Mulch also reduces afternoon soil heating, which can stress roots in the intense afternoon sun.
Frequently asked questions
- What stone fruits grow best in Denver?
Peaches, Japanese plums, and both sweet and sour cherries are reliable. European plums grow but bloom earlier and are frost-sensitive. Apricots are marginal due to bloom timing. Select late-blooming or cold-hardy cultivars specific to zone 6a.
- When should tomatoes be planted in Denver?
Wait until after May 10 to be safe; May 4 is the average last frost date, but late frosts occur frequently. Tomatoes are killed by frost, so early planting is risky. Start seeds indoors in late March for transplants ready by mid-May.
- How do I protect trees from hail?
Hail netting over high-value trees is common in Denver. For unprotected trees, variety matters: smaller-fruited types tolerate hail damage better. Prune for an open canopy that sheds wind and reduces hail impact. Accept some crop loss as inherent risk.
- What's the biggest weather risk in Denver?
Late spring freezes, not winter cold. January and February are cold but predictable. May frosts after warm weather are the killer. Design the garden around variety selection and frost-protection techniques for this critical window.
- How much water do fruit trees need in Denver?
Fruit trees need deep watering once or twice weekly during fruit development from June through August. Denver's semi-arid climate provides limited rainfall for adequate growth. Drip irrigation is far more efficient than hand watering in the low humidity.
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Frost data: NOAA Climate Normals 1991-2020, station USW00023062. Local microclimates can shift these dates by a week or more.
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