Blueberries are among the most popular fruits for home and market gardening. Both highbush and lowbush blueberries are native to North America and are used fresh or processed into jams, syrups, compotes, fruit leathers, and pastries. Blueberries are firm and hold their quality well both on the bush and in refrigeration. The fruits are easy to freeze and retain their quality when frozen. Blueberry crops can be harvested two to three years after planting, and reach maximum production in six to eight years. Several types of blueberries are available to gardeners. In Idaho, select varieties adapted to USDA Plant Hardiness Zones 4-6. As a general rule, for long-lived plants like blueberries, select varieties one, or preferably two, zones hardier than your location.
Besides producing fruit, blueberries are attractive in landscapes. The compact bushes are easy to prune and produce brilliant orange to red foliage in autumn. The fruit attracts birds and other animals, making blueberries valuable in wildlife-attracting landscapes. Depending on the variety, mature bushes range from eighteen inches to ten feet in height.
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Growing Blueberries in the Inland Northwest and Intermountain West
- Half-highs 1 to 3 pounds per bush
- Highbush 8 to 20 pounds per bush
Age to maturity: 6 to 8 years after planting
Productive life: more than 50 years
Hardiness: -15 to -30°F, depending on variety
Optimal pH: 4.2 to 5.2
Exposure: full sun
- Lowbush: 1 foot between plants
- Half-highs: 2 to 3 feet apart in rows 6 to 8 feet apart
- Highbush: 4 to 5 feet apart in rows 8 to 10 feet apart
Selecting a Site
Blueberries require acid soils, which greatly limits where they can be grown in Idaho. A soil pH between 4.2 and 5.2 is ideal (pH 7.0 is neutral). Blueberries can be grown, with some challenges, on sites where the pH is as high as 6.0. Blueberries suffer from iron chlorosis on soils with pH values above 6.0 that are common in southern Idaho and scattered throughout the state.
Soils having pH values between 5.5 and 6.0 can be acidified by incorporating sulfur into the soil one or two years before planting blueberries. Soil acidification is not cost effective for large sites or when soil pH values are above 7.0. For small scale production on sites with heavy soils, poor drainage, or alkaline soils, blueberries can be grown in raised beds or containers filled with potting mixes or amended soil.
Sites with cool, moist, well drained loamy sand, sandy loam, and loam soils containing around 3% or more organic matter are best for blueberries. Coarser soils dry out too easily and clay soils inhibit root growth and encourage root rot. Production on silt loam soils is possible, but can be challenging due to poor water drainage. Muck soils and boggy areas are unsuitable for blueberries unless you can create raised beds at least 14 inches above the soil surface. On some sites, increasing soil drainage with buried drainage tiles can improve blueberry production.
While blueberries survive in partial shade, you need full sun exposure to develop good fruit flavor and maintain high yields. Blueberries grown in the shade become tall, spindly, and unproductive, creating bushes that are unattractive and do not tolerate snow loads well.
Blueberries are among the most cold hardy fruits, but there are differences in varieties. The most cold hardy blueberries tolerate temperatures of -35°F or below, and many varieties survive temperatures between -20 and -25°F. Rabbiteye and southern highbush blueberries are not reliably cold hardy in Idaho.