Vaccinium corymbosum Seeds | Highbush Blueberry
LATIN NAME: Vaccinium corymbosum
COMMON NAME: Highbush Blueberry
Plant Profile
Until the early 1900s blueberries were gathered from the wild, and transplanted bushes died. The United States Department of Agriculture botanist Frederick Coville compared growth in alkaline, neutral and acid ground and found that the highbush plant only thrives in strongly acid soil, an insight he considered his greatest. In 1910 he published the cultural directions that made cultivation possible.
Pick highbush fruit when the whole berry has turned and the stem end has lost its red tone, because the sugars are still rising in the days after the skin colours. A single bush will crop over several passes, firm berries going to the freezer and soft ones to jam, juice or a liqueur; in the kitchen the fruit pairs with lemon, mint and soft cheese, and its juice turns a deep purple in a bottle.
Science & Biotechnology
The highbush blueberry is a tetraploid, carrying four sets of chromosomes rather than two, which is one reason it could be selected so successfully against its diploid relatives. Coville understood that parents had to match in chromosome number before a cross would work, and that the plant is not self-fertile, so two different varieties must stand together for a full crop.
Blueberry roots carry no root hairs. The fine feeding roots instead host ericoid mycorrhizal fungi, which grow inside the root cells and reach out into the raw peat for nitrogen and phosphorus the plant cannot free by itself. The partnership is why the plant hates rich, freshly manured, alkaline soil, and why an established colony of the right fungus matters more than any fertiliser you can buy.
The blue of the fruit comes from anthocyanins, chiefly glycosides of delphinidin, cyanidin and malvidin, sitting in the skin cells. The powdery haze over them is a separate waxy layer that scatters light and is rubbed off by handling. Leaf tissue adds chlorogenic acid and quercetin glycosides, and these are the compounds behind most of the crop’s much-advertised health reputation.
Uses & Benefits
Elizabeth White of Whitesbog, on her family’s cranberry farm, read Coville’s work and offered her land for experiments. She paid local berry pickers to find and mark the best large-fruited wild bushes, and those selections, including the one named Rubel, became the parents of the first cultivated sorts. Coville crossed them, raised thousands of seedlings, and the crop that followed changed a hedgerow fruit into an industry.
Growing from Seed
At a pH between four and five the iron and manganese the plant needs stay soluble and the ericoid fungus works; in neutral or limy ground those nutrients lock up, the leaves yellow between the veins and the bush slowly starves. Peat, pine bark and conifer litter are the raw materials of a blueberry bed, and rainwater is a better irrigation source than tap water over chalk.
Blueberry is propagated commercially by cutting and by tissue culture, in which axillary buds on a sterile shoot are encouraged to break into a multiplying chain of shoots; rooted and hardened off, they give thousands of identical plants from one selected bush. Micropropagation made large, uniform plantings possible, and the practice depends on a sterile medium, a cytokinin to force the buds, and careful weaning of the plantlets into soil.
Sow the extracted seed onto moist shredded peat with a little sand, press it in and barely cover it, then keep the pan humid and cool. Prick the seedlings out when they show their first true leaves and pot them in the same acid compost, and do not feed them until the roots have filled the pot. Water with rainwater, and never lime them.
An established bush wants an even supply of water and a mulch of pine bark or conifer peel that keeps the surface cool and adds acid as it rots. Cut out the oldest canes at ground level once the bush has cropped for a few years, leaving the young stems to carry the next crop, and take the flowers off the first season’s plants so the roots can grow instead of the fruit.
Our Take
Blueberries reward patience and punish busy gardeners, and my own rule is to test the pH before buying a single plant. If you already grow the low, wild European fruit, the bilberry behaves differently and wants even leaner, wetter ground. A pot on a patio is a good start with the compact dwarf blueberry, and my chokeberry article explains the other dark fruit in the same row.
Related Reading
Gardeners who grow Highbush Blueberry often pair it with these related subjects: