Do Blueberries Have Seeds? Who to Ask, and What to Ask Them

Blueberries have seeds, and a lot of them: small, soft, scattered loose through the flesh rather than gathered around a stone. The United States plant patent for the northern highbush cultivar 'Blue Ribbon' records an average of 36 seeds in a berry measuring 17.40 mm across and weighing 2.4 g, with each seed about 1.65 mm long, 1 mm wide and half a milligram in weight. At that size they go down unnoticed. Blueberry seed becomes a practical question in only three situations: when the fruit has been dried, when a hospital has asked for a low-residue diet before a procedure, and when a gardener intends to plant it.

Each has a different authority behind it, and most confusion about blueberry seed comes from asking the wrong one.

How many seeds are in a blueberry

Three kinds of source answer this, each for a different population of fruit.

The plant patent is narrowest and most exact. Patents are sworn botanical descriptions filed to prove a variety distinct, so their measurements exist to be checked by an examiner. U.S. Plant Patent 24,636, granted to Fall Creek Farm and Nursery in July 2014 on an application by David M. Brazelton and Adam L. Wagner, puts 'Blue Ribbon' at 36 seeds per berry.

Wild fruit runs lower and far more variable. Patricia S. Holloway, Professor of Horticulture at the University of Alaska Fairbanks and director of its Georgeson Botanical Garden, opens her Agricultural and Forestry Experiment Station note on Alaskan Vaccinium with the range: "Wild blueberries and lingonberries produce fruit that contain from zero to 40 seeds per berry. The average seed count is 20 seeds per berry." Zero is not a slip. An unpollinated berry can still swell and colour.

Cultivated fruit measured across a full season lands higher again. Bernadine Strik and Amanda Vance of Oregon State University counted viable seed in nine highbush cultivars over two seasons, reporting in HortScience in 2019: 'Bluecrop' averaged 55.5 seeds per berry, 'Duke' 50.0, 'Bluegold' 17.1. Same field, a three-fold spread between varieties.

The USDA Forest Service's Woody Plant Seed Manual counts 2.20 million cleaned highbush seeds to the kilogram, and puts a wild highbush berry at 8 ± 1 mm across, less than half the patented cultivar's 17.40 mm. Breeding doubled the fruit and left the seeds alone.

Why seed counts differ between bushes

Seed number is not a fixed property of a cultivar. It records how well the flower was pollinated, and it moves by a wide margin in a single season.

Kenichi Doi and colleagues at Meiji University in Kawasaki pollinated three highbush cultivars by hand from three pollen sources, publishing the counts in Plants in 2018. 'Collins' left to open pollination set 5.3 seeds per berry; the same cultivar given 'Bluejay' pollen set 19.2. 'Bluejay' pollinated with its own pollen managed 8.0 seeds in a 1.1 g berry, and crossed with 'Herbert' it set 21.2 seeds in a 1.5 g berry.

The seeds are not passengers. Mark Ehlenfeldt and Robert Martin, in a 2010 study of 'Bluecrop' and 'Duke', reported that seed number accounted for as much as 87% of the variation in berry weight. A gardener biting into an unusually seedy homegrown berry is looking at evidence of a good bee year, not a fault.

What a blueberry seed is not

What fruit resembles a blueberry but has a seed? The question is about fruit structure, and it has two answers.

A blueberry is a true berry: one ovary, one fleshy wall, many seeds loose in the pulp. A raspberry is not a berry at all, but an aggregate of drupelets, each a miniature stone fruit carrying its own seed. The plant patent for the raspberry 'ABB 118', granted to Allberry BV in March 2020 on an application by breeder Niels Arts, describes 90 to 100 drupelets with one seed each, every seed about 2.5 mm long. A raspberry of near-identical diameter to a 'Blue Ribbon' blueberry therefore carries three times the seeds, each half again as long, which is why raspberries feel gritty and blueberries do not.

The second lookalike catches foragers. Black huckleberry, Gaylussacia baccata, ripens the same blue-black in the same season. Jennifer D'Appollonio, assistant scientist at the University of Maine, describes its mature fruit for the university's wild blueberry programme as blue-black with 10 seeds, and identifies the plant by the golden resin glands under the leaf. Those 10 are nutlets, up to 2 mm long, and they crunch.

| Fruit | Botanical type | Seeds per fruit | Seed length | Source of figure | |---|---|---|---|---| | Blueberry 'Blue Ribbon' | True berry | 36 average | 1.65 mm | U.S. Plant Patent 24,636 | | Raspberry 'ABB 118' | Aggregate of drupelets | 90–100, one per drupelet | 2.5 mm | U.S. Plant Patent 31,579 | | Black huckleberry | Drupe with nutlets | 10 | up to 2 mm | Univ. of Maine wild blueberry programme |

Huckleberry seed grows huckleberries, which settles the outcome before sowing.

Dried and frozen fruit

Dried blueberries are where people first notice seeds they have been eating for years. Removing the water leaves each seed at full size inside a collapsed berry, so fruit that concealed 36 seeds at 17 mm presents the same 36 in perhaps a third of the volume. Only the ratio has changed.

Frozen fruit matters to the reader hoping to plant supermarket berries. Holloway's Alaska note sets the limit plainly: germination is poor from berries held frozen for a year or more. Short freezing is another matter. The University of Maine's guide to growing blueberries from seed, written by D. A. Abdalla in February 1967, instructs growers to start with berries frozen at least 90 days, using the freezer as the dormancy-breaking treatment rather than as storage.

Are the seeds worth eating

Raw blueberries carry 2.4 g of dietary fibre per 100 g in the USDA's FoodData Central entry, against 6.5 g for raspberries. Most of that gap is drupelet seed. Blueberry seed is oily: John Parry and colleagues, analysing cold-pressed berry seed oils in the Journal of Agricultural and Food Chemistry in 2005, found alpha-linolenic acid at 19.6 to 32.4 g per 100 g of oil. The quantity in a punnet of fruit is negligible.

One diet excludes them outright, and it deserves naming precisely. Endoscopy units put patients on a low-residue diet before colonoscopy, and berries sit on the prohibited side of that handout for two reasons: seeds can lodge in the working channels of the scope, and the pigment stains the bowel wall the clinician is trying to read.

On timing, the units disagree in public. Kaiser Permanente's low-fibre preparation guide begins the restriction three days before the procedure. Lahey Hospital and Medical Center specifies five. There is no consensus figure to quote, and the handout issued by the unit performing the procedure overrides all general advice, this article included.

Growing blueberries from seed

Fresh seed is straightforward. Aalders and Hall, in work reported in the Woody Plant Seed Manual, extracted seed from fresh lowbush berries and sowed it immediately, achieving 80% germination. Everything after that recovers ground lost to drying.

Dried seed needs cold. The manual cites James Ballington of North Carolina State University, in a personal communication, recommending dry cold at 3 to 5 °C for about 90 days. Holloway's window is wider: 30 to 120 days in a refrigerator, never a freezer, with 30 days enough for seed frozen a month or less.

Gibberellic acid substitutes for part of that cold, and its effect is the most useful figure a home grower can carry. Dweikat and Lyrene, testing highbush seed, recorded 4% germination in four weeks from untreated seed against 50% at 900 ppm gibberellic acid. Higher concentrations added nothing. Light is not optional either: Vaccinium seed is photoblastic and needs several hours of daylight, which rules out burying it.

The working procedure, from Holloway's method:

1. Blend half a cup of ripe or thawed berries with water for 30 to 45 seconds, top up, and let the filled seed sink for 15 seconds. Pour off pulp and floaters; repeat until the water runs clear.
2. Sow fresh seed at once onto finely milled sphagnum peat, barely covered.
3. If the seed has dried, cold-stratify it moist at 3 to 5 °C for 30 to 120 days, or soak it overnight in 900 to 1,000 ppm gibberellic acid.
4. Germinate in light at 16 to 21 °C on continuously moist peat. Expect emergence in two to six weeks.
5. Transplant at 25 to 40 mm tall, handling the near-transparent roots as little as possible.

How long until it fruits

Sources disagree about the waiting time, and the gap is too wide to average honestly.

The University of Maine's 1967 guide says seedlings "should bloom and set a few berries when two years old." The 'Blue Ribbon' patent record points the same way: the controlled cross was made in 2002 and the seedling was first selected from a high-density field planting in the summer of 2005, so it had fruited by its third season. Against that, the University of Florida's programme calls blueberry a crop with a long juvenile phase and runs its 10,000 seedlings a year through four sequential field tests taking 10 to 15 years before a release. The positions stop conflicting once the question is split: first berries in two to three years, a defensible verdict on their quality in considerably longer.

What the seedling will not be is a copy. Highbush blueberry is an autotetraploid with 2n = 4x = 48 chromosomes and polysomic inheritance, bred from a pedigree stitched across several species: the Michigan State University patent for 'Draper' records contributions from V. tenellum, V. ashei and V. darrowii inside one northern highbush variety. Such heterozygous tetraploids segregate widely.

Frank A. Blazich, alumni distinguished graduate professor of plant propagation and tissue culture at North Carolina State University, writing with Jason J. Griffin of Kansas State University in the Woody Plant Seed Manual, puts it in one line: "Due to seedling variability, sexual propagation is normally restricted to breeding programs."

Blueberries do not grow true to seed. A seed taken from a 'Bluecrop' berry produces a blueberry bush. It does not produce 'Bluecrop'.

Why the trade roots cuttings instead

The rooting figures explain the entire nursery industry.

Hardwood cuttings of six highbush cultivars treated with indole-butyric acid and assessed after 90 days, in work by An and colleagues in HortScience, rooted best in 'Bluebeauty' at 68.55% and 'Biloxi' at 68.01%, the authors noting that rooting varies sharply by cultivar. Wild Vaccinium does better: José Tejada-Alvarado and colleagues at the Universidad Nacional Toribio Rodríguez de Mendoza in Peru rooted five wild accessions above 90% at 2,000 mg per litre of IBA within 45 days, two at 100%, reporting in Acta Agrobotanica in 2021.

North Carolina State University's Blueberry Genetics and Genomics Laboratory, led by associate professor Hudson Ashrafi, treats the rate as a selection criterion in its own right: cuttings that root at 50% or less flag a variety that "may not make a good cultivar."

Against 4% from untreated seed, a cutting is a genetic copy of the parent at more than fifteen times the success rate.

Who to ask, and what to ask them

Four questions, four filing cabinets. Seed count and berry size sit in the plant patent for the named cultivar, searchable free at the USPTO and written to be verified. Dormancy treatments and germination rates sit in the Woody Plant Seed Manual, which cites the underlying trials rather than summarising them away. What a seedling will do belongs to the breeding programme, never the catalogue. Whether to eat blueberries this week belongs to the unit performing the procedure, whose handout outranks every general article, this one included.

Frequently asked questions

Are blueberry seeds safe to eat?

Yes. Blueberry seeds are soft and roughly 1.65 mm long, and they are swallowed whole in every blueberry eaten. Unlike the stony pips of apples or cherries, they are not removed or avoided in any standard dietary guidance, apart from the low-residue diet ordered before a colonoscopy or bowel surgery.

Do blueberries have seeds inside?

Yes. A blueberry is a true berry, so its seeds sit loose in the flesh rather than in a core or around a stone. The plant patent for the highbush cultivar 'Blue Ribbon' records an average of 36 seeds per berry. Wild blueberries average about 20, ranging from none to 40.

What fruit resembles a blueberry but has a seed?

Black huckleberry, Gaylussacia baccata, is the closest lookalike. It ripens blue-black in the same season and contains 10 hard nutlets up to 2 mm long, which crunch audibly. The University of Maine identifies the plant by the golden resin glands on the underside of its leaves, which blueberry lacks.

Can blueberry seeds be used for planting?

Yes, though germination is low without treatment. Seed sown fresh from ripe fruit germinated at 80% in one reported trial, while dried seed managed 4% untreated and 50% after treatment with 900 ppm gibberellic acid. Dried seed otherwise needs 30 to 120 days of moist cold at 3 to 5 °C.

Can you eat blueberries before a colonoscopy?

Not during the restricted window. Endoscopy units exclude berries from the low-residue diet because seeds can lodge in the scope and the pigment stains the bowel wall. Kaiser Permanente begins the restriction three days beforehand; Lahey specifies five. Follow the handout issued by your own unit.

Why won't a blueberry seedling be the same as its parent cultivar?

Highbush blueberry is an autotetraploid with 48 chromosomes, highly heterozygous and bred from several Vaccinium species. Its offspring segregate widely, so seed from a 'Bluecrop' berry gives a blueberry bush rather than 'Bluecrop'. The Woody Plant Seed Manual notes that seed propagation is normally restricted to breeding programmes.