Shiro is a Luther Burbank heirloom plum that brings unrelenting abundance to gardens across zones 5 through 9. The large, round fruits wear a brilliant sunshine-yellow skin with translucent golden flesh inside, delivering a mild, remarkably sweet flavor that's remarkably juicy. This early-ripening cultivar sets fruit with just 400 to 500 chill hours, making it exceptionally reliable even in maritime climates where other plums struggle. The tree itself grows as a compact, layered specimen reaching 12 to 16 feet tall, and once established, it doubles its fruit production year after year, giving you exponentially more harvest as the tree matures.
Full Sun
Moderate
5-9
192in H x ?in W
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Moderate
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Luther Burbank introduced the Shiro in 1899, and it remains a powerhouse of productivity that few other plums can match. The fruit ripens early in mid-summer with a flavor so mild and sweet you might want a bib for the juice that follows. The tree's naturally short, wide form means you won't struggle with an oversized plant taking over your garden, yet it delivers loads of clingstone fruit that builds steadily in volume with each passing season.
Shiro plums are prized as fresh eating fruit, where their juiciness and mild sweetness shine without any competing tartness. The abundant yields make them natural candidates for preserving, whether you're making jam, compote, or bottling them whole. Gardeners with maritime climates or marginal growing zones specifically value this variety because it succeeds where other plums fail, expanding what's possible in challenging regions.
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Plant bare-root Shiro trees in early spring or fall, positioning them in full sun. Space the tree at least 12 to 16 feet from other plantings to allow its naturally spreading form room to develop. The young tree benefits from consistent moisture for the first two seasons as it establishes; water deeply and regularly rather than light, frequent sprinkles.
Pick Shiro plums when they reach full size and the skin glows a deep sunshine yellow with perhaps a slight blush. The fruit will yield gently to hand pressure, a sign the clingstone flesh is fully mature. Harvest in mid-summer when ripeness peaks, though the exact timing depends on your climate; warmer zones will see fruit ready earlier than cooler regions. The skin should appear fully colored without any green undertones; if you see them still turning from pale to golden, wait another week or two.
Shiro naturally forms a short, wide, layered crown, so minimal pruning is needed once established. In the first few years, light formative pruning encourages the characteristic spreading habit. Remove any crossing or inward-facing branches to maintain airflow and prevent disease pressure, especially important in maritime climates where moisture lingers. Avoid heavy pruning once the tree begins fruiting, as it reduces the following year's harvest.
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“The Shiro plum emerged from Luther Burbank's legendary breeding work in 1899, a time when American pomologists were actively crossing Asian plum genetics with European varieties to expand fruit options across North America. Burbank selected this hybrid from Prunus salicina parentage specifically for its remarkable productivity and adaptability to diverse climates. The variety survived and thrived through the 20th century because it delivered what home gardeners needed: reliable, abundant harvests and a forgiving temperament in less-than-ideal conditions. Today it remains a testament to Burbank's vision of democratizing fruit production, moving superior plum genetics out of specialized nurseries and into everyday gardens.”