Black Ice Plum

Overview

Black Ice is a hybrid plum that has proven itself in some of Montana’s harsher spots, including sites that have dropped to around –40°F. At Rod McIver’s place, which hit –38°F on January 12, 2024, his Black Ice trees came through with only minor tip damage—which is a pretty remarkable performance for a dessert-quality plum in that kind of cold.

History & Breeding

Black Ice was developed by Dr. Brian Smith at the University of Wisconsin–River Falls and released in the mid-2000s (around 2005–2006).

According to info on its release, this complex plum hybrid was built to solve a specific problem:

create a “California-type” large, sweet Japanese-style plum that could still handle Upper Midwest / Zone 3 winters.

Genetically, it combines Japanese plum (Prunus salicina) with hardy native Prunus (variously described as cherry plum or Western sandcherry), which is where it gets its excellent cold tolerance.

Tree Characteristics

• Growth habit: Spreading, somewhat low and wide rather than tall and upright.

• Bearing: Precocious—comes into bearing early, often much sooner than older plum standards.

• Productivity: Very productive when properly thinned; tends to set heavy crops.

• Frost tolerance: Above-average bud and wood hardiness for a dessert plum, designed for cold-winter climates.

Fruit Description & Ripening

• Fruit: Large, round to slightly oval, with dark purple-black skin and firm, sweet flesh—often described as “California-type” in quality.

• Texture & flavor: Firm but juicy, with rich, sweet dessert flavor. Often used primarily for fresh eating, but also suitable for preserves.

• Ripening: Early for a plum of this quality—around early August in many cold-climate locations.

Cold Hardiness & Performance in Montana

On paper, Black Ice is marketed as hardy to about USDA Zone 3, which means survival in an area that sees -35°F on average across a 30 year spread. So the minimum extreme winter low that the tree can see is theoretically lower. Herein lies the issues, though with going off of the USDA hardiness map, which is that what the absolute extreme is that the tree can observe based on this 30 year average extreme is anyone's guess. So to be conservative, we are listing this at simply being able to withstand -38F with minor winter injury.

In the field:

• It has been grown reliably in parts of Montana that see –35°F to –38°F as their extreme mid-winter cold, especially in favored microclimates with good air drainage.

• At Rod McIver’s site, where the temperature dropped to –38°F on January 12, 2024, his Black Ice trees came through with only minor tip damage

• Montana Growers east of the divide who see temps sub –38°F should be cautious when growing Black Ice. This would likely only be areas in near Billings (Joliet, Bridger, Belfry, Red Lodge, Park City) and even the warmer microclimates in those areas at that.

For most growers in Western Montana, Black Ice is one of the better candidates if you want:

• A true dessert-type plum (not just a wild American plum)

• And you still regularly see –30°F or colder in a bad winter

Pollination

Black Ice is not self-fruitful. It needs a compatible pollinizer:

• Recommended: Toka

• Other compatible hybrid or American plums can also work, as long as bloom times overlap.

• Pollination chart coming soon if it isn't already on the site