Growing blueberries in the home garden
- Several species of blueberry are indigenous to the United States. These include the lowbush blueberry (Vaccinium angustifolium) found in Maine and Canada; the rabbit eye blueberry (V. ashei) grown in the southern United States; and the Northern highbush blueberry (V. corymbosum), the species most widely grown in Maryland.
- There are several other native blueberry species growing wild in Maryland. Rabbiteye blueberries can be grown in warmer areas of the state, and Southern highbush blueberry (a cross between Northern highbush and V. darrowii, native to the South) is proving to be an excellent choice for most locations east of Frederick, MD. Northern highbush blueberry is the most cold-hardy of the major cultivated types of blueberry.
- The blueberry plant is a multi-stemmed shrub, consisting of a shallow root system and woody stems, or canes, that originate from the crown of the plant. The root system is very fibrous but devoid of root hairs. (Root hairs function in most plants by increasing the surface area of the root for water and nutrient uptake.) This characteristic makes the blueberry plant very sensitive to changing soil/water conditions.
- A mature, cultivated blueberry usually has 12 to 18 canes. Growth habits vary among cultivars, with some bushes growing very upright and others having a more spreading growth habit. The fruit is borne on buds formed the previous growing season.
- Soil preparation should begin about 6 months before you order and plant your blueberries. Begin by testing the soil then prepare the soil using your soil test results as a guide. For gardeners, soil testing labs provide the most accurate pH measurement of your soil, as well as baseline information on organic matter and nutrient levels.
Recommended blueberry cultivars
It is recommended to select a combination of cultivars that can provide a continuous harvest from July through mid-September. Blueberries are self-fertile but produce more and larger berries when two or more cultivars are planted. Be sure bloom times overlap. Purchase 2- to 3-year-old plants.
|Short, compact bushes with medium vigor. Medium size, crack-resistant fruit with good flavor.
|Very vigorous bushes with mummy berry disease resistance. Large, firm, slightly tart berries. Fruit does not drop or crack.
|Very productive and vigorous variety that performs well in hot climates. Large, high-quality berries.
|Leading variety; hardy and consistent with vigorous, upright canes. The fruit is large, firm, and crack-resistant.
|Large, crack-resistant fruit holds well on canes. Very productive and upright canes.
|Small, firm, flavorful fruit borne on erect, vigorous canes
|Very late and ornamental bush with red wood. Small to medium-size fruit does not crack or drop.
|Vigorous, upright plant with large firm fruit.
|Upright 6 ft.-7 ft. bush with medium-size firm berries.
|Early, low-chill cultivar with large heat-tolerant fruit fruit
|Low chill, heat-tolerant cultivar that ripens mid-season.
per plant (lbs.)
|Yrs. from planting
to the first crop
|Plant more than 1 variety for highest yield
When to plant blueberries in Maryland
Plant blueberries as soon as the soil can be worked in the spring or one month before the first fall frost (mid-to-late September).
If plants are purchased in containers: Make the planting hole 2-3 times the rootball width so the roots can be spread out.
If bare-root plants are purchased by mail: When your order arrives, unpack the bundles and inspect the plants. The roots should be moist and have a bright, fresh appearance. Shriveled roots indicate that the plants have been allowed to freeze or dry out in storage or transit. Such plants seldom survive. Plant roots must be kept moist and free from freezing temperatures at all times.
Set plants at the same depth as they were planted in the nursery. Keep young plants well-watered. Blueberries, in particular, will not tolerate water stress.
Where to plant blueberries
Blueberries generally prefer full sun but can tolerate some shade. With Maryland’s climate becoming warmer, some light afternoon shade may prove beneficial. Try to avoid windy, dry sites. Healthy, mature blueberry plants will generally tolerate very cold temperatures, although there is some cultivar variation. Winter injury is more likely to occur when a period of mild winter weather is followed by severe cold. Most varieties require 500-750 hours of chilling below 45°F. In Maryland, this requirement is usually met no later than early February. After the chilling requirement is met, the plant loses its dormancy and, thus, its cold hardiness, making it increasingly susceptible to cold injury.
Preparing the soil for blueberries
- Blueberries are in the heath family and thrive in acidic soils (pH 4.3 - 5.3) high in organic matter. The year before planting, you should increase soil organic matter by incorporating manure or cover crops, then test and amend your soil pH according to soil lab recommendations. It's likely that the soil pH will be greater than 5.5, requiring the addition of sulfur.
- It takes some time for sulfur to lower the soil pH, so these materials should be added in the fall before planting. Sulfur does not move through the soil readily, so surface sulfur applications after the plants are in place are not very effective in lowering the pH. Sulfur should be incorporated into the soil 6-8 inches deep.
- Special bacteria in the soil transform the added sulfur, releasing hydrogen ions that lower the soil pH. These bacteria are most effective at soil pH levels below 6.0. Therefore, it is important to add both sulfur AND iron sulfate when soil pH is above 6.0. Sulfur alone is sufficient if soil pH is below 6.0. Please refer to the table below.
- A soil pH that is too low can result in manganese or aluminum toxicity. Never attempt to lower pH with aluminum sulfate. As the pH decreases, aluminum becomes more available and may be taken up by plant roots at toxic levels. High pH results in the unavailability of certain nutrients, like iron, which results in chlorosis of the leaves (yellowing or bleaching of leaves between leaf veins).
- At planting time, amend the entire planting site, not the individual planting holes, with compost or compost and peat moss, to improve water-holding capacity. The final growing medium should be 1/3 or more organic matter (by volume) at planting time. In many cases, well-maintained blueberry plants grow and produce well when grown in high organic matter soils with soil pH >5.3.
Lowering soil pH for blueberries
Approximate pounds of sulfur or iron sulfate needed per 100 sq. ft. of soil to reduce the soil pH to 4.5 for blueberries. It is not necessary to use iron sulfate if soil pH is below 6.0. Sulfur alone will suffice to lower the pH.
(flowers of sulfur
or elemental sulfur)
Sulfur (flowers of sulfur
or elemental sulfur)