Fruit trees face considerable challenges in Wyoming due to the state’s severe continental climate, characterized by extreme cold, high altitude, and a short growing season. The combination of frigid winters and the threat of late spring or early fall frosts makes successful fruit cultivation difficult for standard varieties. By selecting exceptionally cold-hardy species and implementing specific cultivation strategies, it is possible to harvest a variety of fruits. This article details the environmental constraints and identifies the cultivated and native fruit trees and shrubs best suited for thriving in this demanding environment.
Navigating Wyoming’s Growing Zones and Climate
Wyoming’s climate is the primary limiting factor for fruit tree selection. Most of the state falls within USDA Hardiness Zones 3b through 5b, where minimum winter temperatures can drop to -35°F to -15°F, respectively. The high elevation, often exceeding 4,000 feet, contributes to intense solar radiation and a high risk of desiccation from strong winds throughout the year. Only trees capable of surviving these extreme low temperatures when dormant have a chance of long-term survival.
The short growing season, coupled with unpredictable frost dates, poses a threat to flower buds after they break dormancy in spring. Even cold-hardy trees can lose an entire crop if a late frost event occurs after blooming. Therefore, successful varieties must not only tolerate the winter cold but also have a late bloom time or require a very short time for fruit to ripen.
Cultivated Pome and Stone Fruits That Thrive
For pome fruits, cold-hardy apple varieties are the most reliable cultivated tree fruit in Wyoming and have been grown in the region since before statehood. Varieties originating from the University of Minnesota breeding program, such as ‘Honeycrisp,’ ‘Zestar,’ and ‘State Fair,’ are recommended for their ability to withstand the cold. The ‘Frostbite’ apple is an excellent choice for the coldest areas, delivering a sweet and tangy fruit that ripens in late September.
Apple trees should be grafted onto extremely cold-tolerant rootstocks, such as Antonovka, which provides a full-sized tree with a resilient root system. Pear trees are also possible, with the Ussurian pear (Pyrus ussuriensis) or its hybrids like ‘Ure,’ ‘Gourmet,’ and ‘Luscious’ offering the necessary hardiness. These varieties often survive temperatures down to -25°F when dormant. Selecting pear varieties that mature early is advisable to ensure a harvest before the first hard fall frost.
For stone fruits, sour cherries and hybrid plums are significantly more successful than their sweet counterparts. Tart cherry varieties like ‘Montmorency’ and ‘North Star’ are highly recommended for their cold tolerance and ability to produce fruit. While sweet cherries like ‘Black Gold’ and ‘White Gold’ can be grown in some lower elevation areas, their yields are inconsistent, often producing a light crop only once every four or five years.
Hardy American hybrid plums are better suited for the climate than European plums. Recommended varieties include:
- Superior
- Bubblegum
- Waneta
- Ember
The ‘Superior’ plum, a cross between a Japanese and American hybrid, is cold-hardy and can be grown at elevations up to 8,000 feet. Planting these fruit trees on semi-dwarf rootstocks is often preferred for residential landscapes, as they grow to a manageable height of about 15 feet and are more wind-resistant than dwarf varieties.
Successful Native and Small Fruit Varieties
Native species provide a reliable alternative, as they are naturally adapted to the intense cold and high-altitude conditions. The chokecherry (Prunus virginiana) is a large, multi-stemmed shrub or small tree native to Wyoming that produces fruit in late summer. These berries are typically used for jams and preserves.
Another excellent native option is the serviceberry, also known as juneberry (Amelanchier alnifolia), which is found on open hillsides. The fruit is borne on shrubs that can reach up to 15 feet tall and is highly valued for its extreme hardiness. The American plum (Prunus americana) is another very hardy native species, producing fruit in drainage areas and canyons of the plains.
Small fruit bushes and shrubs offer a dependable harvest and are easier to protect from harsh weather. Raspberries, which are native to Wyoming’s mountains, are self-fertile and a popular choice for the home gardener. Currants and gooseberries are also extremely hardy small fruits that tolerate the cold better than standard tree fruits. Gooseberries, closely related to currants, are small shrubs preferred by many for making pies and jams.
Essential Strategies for Winter Survival
Selecting the right cold-hardy variety is the first step, but providing active winter protection is necessary to ensure survival and consistent production. Proper site selection is important; planting on a gentle slope helps cold air drain away, preventing frost pockets that damage early blooms. Placing trees on the south side of a structure can help moderate temperature swings, but the trunk must be protected from sun scald.
Sun scald occurs when the winter sun warms the tree’s bark during the day, followed by rapid freezing at night, causing the bark to crack. To prevent this, the lower trunk should be wrapped with a white tree guard or painted with a diluted white latex paint to reflect sunlight. This wrapping also deters rodents, like rabbits and voles, which can girdle young trees by chewing the bark during winter.
Arid conditions and high winds cause trees to lose moisture even in winter, making deep watering a necessary late-fall strategy. A thorough soaking just before the ground freezes helps prevent desiccation, which is a major cause of winter injury in young trees. Finally, using a layer of organic mulch, such as wood chips or straw, around the tree’s drip line insulates the roots against deep freezes and prevents damaging freeze-thaw cycles.