Local planting guide · Mountain West
zip 80035
Westminster 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 Westminster
Week 18 priorities
On the docket: transplant out after last frost · direct sow after last frost. See the full calendar →
Gardening in Westminster
Westminster sits in zone 6a at roughly 5,300 feet elevation, which shapes both limitations and opportunities. The 156-day growing season runs from the May 4 average last spring frost through the October 8 first fall frost, a window wide enough for established fruit trees to thrive but tight for long-season vegetables. The dominant constraint is not cold but timing: late spring frosts frequently coincide with fruit tree bloom, and the sharp frost transition in early October cuts off the season abruptly. Colorado's low humidity is an asset most gardeners overlook. Fungal diseases common in the humid East (apple scab, cedar-apple rust, powdery mildew) are far less aggressive here; disease pressure from rainfall and wet foliage is negligible. Conversely, the intense high-altitude sun and low humidity demand consistent irrigation even during the shoulder seasons. Stone fruits (peaches, plums, cherries) perform reliably in Westminster, as do pears and apples, though orchard design must account for spring frost risk and high wind exposure.
Regional context · Mountain West
What the Mountain West brings to Westminster
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 Westminster
Three weather phenomena defeat most Westminster growers consistently. Late spring frosts remain the primary culprit: May 4 is late enough that apple, cherry, and stone-fruit buds have often broken dormancy and begun blooming, making them vulnerable to frosts that occur even weeks after that date. Hail is the second major threat, particularly June through August when convective storms develop in the afternoon; a single hail event can strip leaves and damage developing fruit, setback trees by weeks, or strip a year's crop. Third is the rapid moisture loss in spring and fall: despite cool temperatures and moderate frost dates, irrigation must begin in May (before trees leaf fully) and cannot cease until after the first fall frost, as trees are still establishing water reserves in early October.
Crops that grow in Westminster
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 Westminster
Year-view of seed starting, transplanting, planting, pruning, fertilizing, harvest, and pest-watch windows tuned to Westminster's local frost dates.
Week ? · loading
This week in Westminster, CO (zone 6a)
Quiet week in Westminster, 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 Westminster
Variety timing matters sharply here. Select apple and stone-fruit varieties that bloom late relative to the May 4 frost date, such as 'Fuji', 'Gala', 'Arkansas Black', and 'Contender' peach. Early-bloomers like 'McIntosh', 'Jona Gold', or 'Redhaven' routinely lose crops to post-bloom frosts. Second, invest in frost protection for high-value plantings: frost cloth for small trees, microclimate placement (south-facing wall, low-lying areas where cold air drains), and frost-hardy companion plantings can offset the timing mismatch. Third, irrigation strategy: drip systems or soaker hoses are essential, not optional. Apply water deeply and infrequently rather than frequent light sprinkling; the growing season compresses into a narrow window and water stress in May or late September directly impacts winter hardiness and bloom set for the following year.
Frequently asked questions
- What fruit trees grow most reliably in Westminster zone 6a?
Apples, pears, sour cherries, and European plums are the safest choices. Sweet cherries and Japanese plums can succeed but are more sensitive to late frosts and require more careful variety selection. Peaches are possible with late-blooming selections. American persimmons are cold-hardy but may not reliably set fruit due to pollination challenges at this latitude.
- Why do fruit trees often bloom before the last frost, and what can be done?
Westminster's May 4 average frost date is late relative to bloom time. Trees exposed to warm spells in March or April break dormancy early, then frost kills exposed flowers. Delay bloom by avoiding south-facing exposures (north-facing is slower to warm), planting in slightly lower or shaded microclimates, and choosing later-blooming varieties. Frost cloth on small trees is effective for critical nights.
- How much water do fruit trees need in Westminster's dry climate?
More than zone 6a growers in humid regions. Start regular irrigation in May, apply 1 to 1.5 inches per week (including rain), and continue through October. Drip irrigation is more efficient than overhead; water early morning to minimize evaporation. Winter dormancy does not mean no water; deep watering in October before freeze-up is critical for winter hardiness.
- Is hail a real risk to my orchard?
Yes. The Denver metro area averages 7 to 10 hail days per year, often in June and July when trees are leafed-out and setting fruit. There is no reliable protection; consider planting in a location with natural wind-break (mature trees, hillside) to mitigate damage. Crop insurance for hail is available from some providers.
- Can I grow vegetables in Westminster?
Yes, but the 156-day season demands careful timing. Cool-season crops (lettuce, peas, kale) thrive in May and September-October. Warm-season crops (tomatoes, peppers, squash, beans) must be started indoors in March for transplants and mature before October 8. Succession planting is difficult due to the compressed window.
- What's the biggest single weather risk for orchards in Westminster?
Late spring frost. A May frost after bloom is more damaging than winter cold, because entire crops are lost while the tree survives. This risk shapes every other decision: variety selection, microclimate, frost protection, and even whether to attempt high-value crops.
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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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