Gardening in the unique climate of Colorado presents a distinct set of challenges that require thoughtful planning and specific plant choices. The state’s varied topography means gardeners face conditions far different from more temperate regions. Success relies on understanding these environmental factors and selecting varieties adapted to withstand them. This guide focuses on plants that thrive under Colorado’s demanding conditions.
Navigating Colorado’s Unique Growing Environment
Colorado’s growing season is defined by its high elevation, which introduces several complex variables for plant life. The air is thinner, resulting in significantly increased solar intensity and ultraviolet (UV) radiation that can easily scorch or dry out sensitive foliage. This intense sun, combined with low humidity, causes rapid moisture loss from both the soil and the plants themselves.
The high altitude also contributes to a short, often unpredictable growing season, where the average last frost date can extend well into June in mountainous areas. Nighttime temperatures frequently drop, even during summer months, which limits the accumulation of “growing degree units” necessary for many warm-weather crops to mature. Gardeners must consult the USDA Hardiness Zones.
Soil composition adds complexity, as Front Range and plains areas often feature heavy, dense clay. This clay soil is generally highly alkaline (pH ranging from 7.0 to 8.3), which can lock up certain nutrients, making them unavailable to plants that prefer acidic conditions. Furthermore, this heavy clay is often expansive, meaning its volume changes dramatically with moisture content, which can be stressful for root systems.
Essential Strategy: Selecting Water-Wise Plants
Given the semi-arid nature of the state, adopting a water-wise landscaping strategy is essential for long-term success. This methodology, often referred to as Xeriscaping, focuses on designing landscapes that minimize or eliminate the need for supplemental irrigation. The core principle involves training plants to develop deep, resilient root systems by watering deeply but very infrequently.
A practical application of this strategy is water zoning, which involves grouping plants with similar moisture needs together in the landscape. This prevents the overwatering of drought-tolerant species and ensures that high-water-use plants are confined to small, easily managed areas. Efficient irrigation is best achieved using drip systems or soaker hoses, which deliver water directly to the root zone, drastically reducing loss from evaporation.
Mulching is another effective technique, helping to conserve soil moisture, regulate soil temperature, and suppress competitive weeds. Applying a layer of organic mulch, such as wood chips, around plants helps keep the soil surface cool and moist. For native plants, which prefer leaner soil, careful use of compost or aged manure can improve structure without making the soil overly rich, which can sometimes shorten the lifespan of xeric varieties.
Recommended Plant Varieties for Success
Selecting plants that naturally tolerate the intense sun, alkaline soil, and low moisture is the direct path to a thriving Colorado garden. Native and adapted species have evolved mechanisms to cope with these specific environmental pressures. Trees and shrubs provide the necessary structure and shade while requiring minimal water once established.
Trees and Shrubs
The Ponderosa Pine is an excellent choice, known for its extensive taproot system that allows it to tolerate prolonged drought conditions by accessing deep water reserves. Similarly, the Bur Oak is remarkably resilient, handling both drought and poor soil conditions common across the Front Range. For smaller spaces, the Rocky Mountain Juniper is a hardy evergreen that provides year-round color and requires little water once mature.
Low-water shrubs like Apache Plume and Rabbitbrush offer beautiful texture and flowers with minimal maintenance. Apache Plume produces white, rose-like flowers followed by feathery seed heads, while Rabbitbrush is valued for its late-season golden-yellow blooms. The Mountain Mahogany is another rugged, drought-tolerant shrub that handles high elevations and dry soils.
Perennials and Groundcovers
Perennials are foundational to a water-wise landscape, offering color without the constant need for replacement. Rocky Mountain Penstemon is a native favorite, producing vibrant blue-purple spikes that attract pollinators and thrive in dry, sunny conditions. Sedum varieties, with their succulent leaves, are perfect for rock gardens and withstand extreme heat and drought.
For long-blooming color, Blanket Flower and Russian Sage are reliable, low-water performers that handle the intense sun well. Groundcovers like Blue Grama Grass are tough, native prairie species that work as a low-maintenance alternative to traditional turf.
Edibles and Vegetables
Successful vegetable gardening focuses on selecting varieties with short maturity windows to accommodate the limited number of frost-free days. Cool-season crops tend to perform best because they tolerate the cooler nighttime temperatures and the short season. Leafy greens, including spinach, kale, and Swiss chard, can be planted early and harvested through the summer.
Root vegetables are particularly successful because the soil provides insulation from temperature swings; carrots, beets, and radishes are reliable choices. For warm-season crops like tomatoes, gardeners should select varieties bred for short maturity times. Utilizing raised beds is a common strategy to help the soil warm up faster in the spring, effectively lengthening the usable growing period.