Blueberries - Selection, Soil Preparation, Planting

Selection

It is possible 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. 

Recommended blueberry cultivars

Planting

General information on planting blueberries

Timing

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. Plant as soon as the soil can be worked in the spring or one month before the first fall frost (mid- to late September). Set plants at the same depth as they were planted in the nursery. Make the planting hole 2-3 times the rootball width so the roots can be spread out. Keep young plants well-watered. Blueberries, in particular, will not tolerate water stress.

Site Selection

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.

 
Blueberry showing foliage burned by excessive heat against brick wall

Soil Preparation

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 time, so these materials should be added 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, peat moss, or shredded leaves, to improve water-holding capacity. The final growing medium should be 1/3 or more organic matter (by volume) at planting time.

Approximate pounds of sulfur and iron sulfate needed per 100 sq. ft. of soil to reduce the soil pH to 4.5 for blueberries

*flowers of sulfur or elemental sulfur.
**It is not necessary to use iron sulfate if soil pH is below 6.0. Sulfur
     alone will suffice to lower the pH. 

Additional Resource

•  Planting blueberries in containers 

Back to Top