Acme Plum Tree
- Zone 2
Characteristics of the tree
Acme is a small-medium plum, round and slightly ovate, about 5cm in diameter and weighing approximately 18g. Its skin is red with a bluish bloom, over an orange background, and the flesh is yellow. The skin is moderately acidic, while the flesh is juicy and sweet, with a delightful aromatic flavour. It’s a real treat for fresh eating, and it is also semi-freestone, a considerable advantage if one wishes to use it in cooking. It is ready to harvest at the end of August or early September, and like most stone fruit, does not keep for long.
The Acme plum tree is vigorous and upright, spreading into a vase shape. It is hardy in zone 2, making it a truly excellent choice for northern fruit growers. It displays good disease resistance, especially to brown rot. Acme originates from a seedling of Pembina, which in turn was a cross between a Japanese Plum (P. salicina) and a Canada Plum (Prunus nigra). It is self-sterile and needs to be pollinated by a Canada Plum or an American plum.
Acme was introduced in 1960 by the University of Saskatchewan. It originates from a seedling of Pembina, and greatly resembles its parent, to the extent that a paper by Rick Sawatzky of the University of Saskatchewan suggested that it was ‘probably genetically identical to Pembina.’ However, when comparing the two trees and the plums, we have observed small differences and particularly a marked difference in that Acme is more disease-resistant than Pembina. Pembina, in its turn, was developed by Dr. N.E. Hansen in ‘South Dakota State, College of Horticulture experiment grounds; the product of a cross between Assiniboine (supposed to be actually Prunus nigra) and Red June, a cultivar of Prunus salicina. It was introduced in 1917.
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.
