Bloomsweet Grapefruit, Kinkoji

Origin

Kinkoji is an old Japanese citrus whose parents are unknown. The citrus collection of the University of California, Riverside, received it as seed from Okitsu, in Shizuoka Prefecture, in 1963, and lists it under the historical botanical name Citrus obovoidea and the synonym Marumero; the reference work The Citrus Industry treats it as a pummelo × mandarin hybrid. In Texas it is grown and sold under the name Bloomsweet grapefruit, a name popularized by Houston-area growers who planted it in their yards for its tolerance of cold.

Tree description

The tree is vigorous and upright, reaching 10 to 13 ft (3 to 4 m), with long, pointed leaves on winged petioles that recall those of a grapefruit, and some thorns. Its cold tolerance is better than that of common grapefruits: growers in Texas report that mature trees survive about 14 to 15°F (−10 to −9°C), while some growers in the Pacific Northwest rank it only slightly hardier than a Satsuma. No published trial has measured it, so treat these figures as an estimate, protect young trees, and favor a sheltered spot on a trifoliate-type rootstock.

Fruit quality

The fruit is large, yellow-orange, round to slightly pear-shaped, with a thick rind of about a quarter of an inch (5 to 6 mm). The flesh is juicy and tender, mildly acidic, low in sugar and free of bitterness. Each fruit holds about 10 to 15 seeds. At Riverside it ripens from October to November, and it can hold on the tree into winter.

Flavor and ornamental interest

Its mild taste, without the bitterness of grapefruit, makes it pleasant to eat fresh or juiced, and its thick, fragrant rind suits marmalade and candied peel. Laden with golden fruit at the start of winter, the tree is also an attractive specimen for gardens in USDA zones 8b and 9, where few grapefruit-type citrus can stay outdoors.