The Berry Grower by Blake Cothron is the essential guide for growing and marketing organic small fruits and berries. Today, we share an excerpt from the book that talks about cultivating and planting blueberries.
Excerpt from Chapter 11 - Blueberries
Having originated in quite acidic, well-drained, high organic-matter regions, [blueberries] have very specific needs for soil pH, drainage, and soil type. Blueberries generally do best in freely draining sandy soils. They can succeed in loamy soils too, but clay soils are often out of the question unless very heavily amended, and doing this beyond a small row or two is usually impractical. Altering soil pH is playing with complex chemistry and can turn wrong very fast if you’re not very specific and mindful. Heavily alkaline or chalk soils will not work. So, all that being said, I would not recommend most people try to get into blueberry production unless you are sure blueberries are already being grown profitably in your area, and you have very thoroughly done your homework on your site and soil type and are sure they are both suitable for blueberry culture.
A few technical things to go over: blueberry soil must be high in organic matter and have a pH in the range of 4–5.5. If it’s over 6 pH, blueberries will not be able to assimilate iron in the soil and will express iron chlorosis symptoms. Too low of soil pH can result in aluminum or manganese toxicity issues. Soil organic matter should be over 3%. CEC (cation exchange capacity) should be low, below 12, as on sandy soils. Otherwise, changing the pH will prove unrealistic. Elemental sulphur can be used to lower the pH for blueberries. Make sure to get a soil test and consult your local ag extension office.
Great regions conducive for easily growing blueberries (species differ) include parts of Maine, Michigan, and New England (lowbush, half-high, and Northern highbush species), and the Deep South in sandier parts of Central and Southern Mississippi/Alabama/Georgia, Louisiana, and Florida (Rabbiteye and Southern highbush species). In the sandy soils of the Deep South and Gulf areas blueberries grow prolifically and yield huge, high-quality crops. For example, south-central Mississippi is where the “blueberry capital” of Biloxi is located, a major commercial blueberry area. California is also a major producer and they grow quite well in the PNW. Chile is a major producer in South America.
In Midwestern and Mid-Atlantic areas, blueberries can succeed if planted in very well-draining loamy or highly sandy soil that is heavily and scientifically amended and great care is given. I have personally planted them in KY on at least three different sites and they have failed every single time, despite carefully amending the loamy clay soil, careful selection of cultivars, good after care, etc. (yet I am trying again in 2022!) Another local KY farm grew blueberries successfully for years until they all suddenly died due to a deadly pathogenic soil fungus called phytophthora root rot, caused by excess soil moisture. Another local aspiring blueberry grower consulted with the local agricultural extension office about amending his soil prior to planting a hundred or more blueberries. He followed their recommendation exactly, amending the soil to adjust the pH to make it more acidic. He planted, and all the plants rapidly died.
Blueberries are sensitive, relatively slow growing plants and generally not that easy to grow, especially on any scale, unless, once again, you are in blueberry country or very dedicated to doing very careful and specific soil amendment.
Plant blueberries in either fall or spring. In Northern areas plant in spring only, to avoid freeze-thaw cycles that can heave young plants right out of the ground, as well as to avoid winter deer browsing and severe low temperatures. In the South, fall or spring planting is fine. Always heavily mulch new plantings.
If your soil is not mostly sand then it likely will require considerable amending. You should do this at planting or before, as it’s not possible after planting! Replace 1⁄2 the original soil out of each 24" deep planting hole with moistened peat moss, mixed thoroughly with the native soil. A small amount of finished compost can be mixed into the peat moss which increases organic soil matter. Make sure the amended soil is firmly packed into the hole (but not compacted down) so the blueberry will not sink down after planting. A deeper hole is better for the shallow, fine root system, allowing it to stay moist and cool when summer gets hot and dry.
It is also recommended at planting time to break up the rootball, especially on larger potted stock. Otherwise, the plants can have difficulty with extending their tiny roots out into the surrounding soil, thus leading to serious problems with nutrient and water uptake that can lead to failure.
After planting each bush, top dress with organic mixed fertilizers, water, and 6–8 inches of organic mulch. Raised beds bordered with untreated wood can hold the heavily amended soil and mulch, improving drainage, and also help with weed control. If the organic matter content of your soil is low, you should cover crop with grasses (sorghum-sudan in summer, rye/legumes in fall-winter) for a year before establishing any sizeable blueberry planting.
Blueberries are spaced within the rows according to species, with lowbush needing 1–2' between plants and highbush 4–6' (usually 6' is recommended). Space rows according to your pathway maintenance equipment/mowers or lack thereof, and the height of the crop.
The plants need about 4–5 years of establishment before you get into substantial production, and are considered mature at age 7. Generally, 2-year-old bushes are what growers plant, often transplanted from 1–2 gallon pots. Always go with container-grown blueberries and not bareroot. Gently scratch the sides of the root mass to loosen the tiny feeder roots at planting. Myccorhizal innoculants are available specifically for blueberries, manufactured in Europe.
Very important to note is the recommendation to remove any and all flowers and tiny fruitlets from the plants for the first 2–3 years. Failing to do so may get you a tiny harvest of berries the first couple of years, but can permanently stunt the bushes, ruining future yields. So, you must be patient and strictly give the bushes 2–3 years to establish before allowing them to fruit at all. Some claim this isn’t necessary, but better to err on the side of caution.
Blueberry cultivars vary rather dramatically, from bloom time to ripening date, size and flavor, so choose carefully. Some are more sweet, others more tart. Tart berries are excellent for baking and retain their true blueberry flavor in the oven, but may prove unpopular at the market. Some make large berries the size of nickels or even quarters, others smaller than peas. Some, like Rabbiteye types, are better in the hot South. Some take time to sweeten up past the initial blue color change, remaining tart for a while, such as ‘Bluecrop’. There is a market for blueberry twigs and foliage for cut flower arrangements. For that, the cultivar ‘Misty’ makes especially lush and green foliage that persists into winter. Make sure your cultivar choices are fully compatible with your region, local climate and marketing route. Early-ripening cultivars also bloom earlier, and are thus more vulnerable to late freezes and frosts.