Alderman Plum Tree - Zone 4
Characteristics of the tree
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Alderman is a medium to large Japanese-type plum. It is 2 – 2 ½ inches in diameter on average, and appealing in appearance overall: the skin is a deep burgundy red and the flesh is a golden hue. The plum is clingstone, firm but juicy in texture, and very sweet especially for a Japanese plum. Its firm texture is a benefit when using it for preserves as well as for fresh eating. It also means that it can keep slightly longer than most plums, although like most stone fruits it does not store well without processing. Alderman ripens late, around late August.
Alderman is an attractive plum tree, exhibiting vigorous growth and profuse flowering, making it an excellent addition to any landscape. It is a precocious and heavy bearer, often giving fruit after two years. It can provide yields of 100-130lbs at maturity even in very harsh climates. It is an annual bearer, and there are no known problems with disease. The tree is self-sterile, meaning it will require a wild plum such as the Canada Plum for pollination. It is hardy to zone 4.
The origin of the Alderman plum tree is quite interesting. It was developed at the University of Minnesota, where some of the earliest hardy plum varieties were developed in the early 1900s. The University’s plum breeding program underwent a significant decline in the late 1960s onwards, having briefly flourished in the middle of the century. This decline was mainly due to the increased availability of imported fruit, coupled with the difficulty posed by the early flowering of plum trees in the northern climate.
During this time, when there was almost no more breeding work being done, a few trees were forgotten for several years in the yard of a university employee. In the early 1980s, it was remarked that the trees were particularly graceful, and more importantly, produced delicious sweet fruit every year. The new variety, the result of an earlier cross between Burbank and Older, was named Alderman after one of the most important leaders of the fruit breeding program in Minnesota. It was released to the public in 1985.
Plums are fast-growing trees, but stay relatively small. A plum tree at maturity will not usually exceed 5 metres or 16 feet in height. Its life expectancy is also quite short: one can generally expect it to live between 30 and 50 years. This illustration shows a 20-year-old plum tree that has attained its maximum height.
You should note that this illustration is meant only to give a general indication of what you can expect, and the growth of your tree might look somewhat different. The development of a tree depends on the soil type, irrigation, fertilisation and climatic conditions. What we show here is based on our observation of the growth of plum trees in zone 4, in rather poor soil. In zone 2, growth will probably be slower, while in a rich soil it could be faster.
All our plum trees are sold bare-root, without pots. They have been cultivated directly in our soil. Bare-root trees must be taken out of the ground and shipped during their period of dormancy, which is why we only ship trees in the spring. A big advantage with these kinds of trees, is that they take up very little space, and can therefore be easily shipped by mail all over Canada!
This photograph shows a 2-3-foot plum tree, just like one that you might receive. Depending on the height you choose at the time of purchase, the tree might be a little smaller (1-2 feet) or somewhat taller (3-5 feet.)
Our plum varieties are hybrids of Canadian, American and Japanese plums. If you are thinking of planting a plum tree, it is important to understand how their pollination works. Hybrid plum trees are self-sterile, and cannot produce fruit alone. Moreover, they are not good pollinators for one another. Even if you plant two different varieties next to each other, you are unlikely to harvest any fruit.
Instead, hybrid plum trees need a wild plum tree to pollinate them: either the Canada plum (Prunus nigra) which is considered the best pollinator, or the American plum (Prunus americana) which also works well. So if you intend to plant plum trees, you must also plant at least one of these nearby, unless of course you already happen to have one. One wild plum tree is enough to pollinate up to around five grafted plum trees.
One drawback of plum trees is that they tend to flower early, making them sensitive to freezing in late frosts. Some microclimates help to mitigate this, such as the proximity of a lake or ocean. We also have a trick to help prevent them from flowering too early: applying a layer of mulch or compost underneath the base of the tree while there is still a good amount of snow on the ground. This insulates the snow underneath, so that it melts more slowly, and by maintaining a colder environment around the base of the tree, delays the start of its flowering period.