Selection of Plum Varieties for Northern Backyard Orchards
Article Overview This article reviews plum varieties for northern climates suitable for including in backyard orchards. It also includes notes about the nutritional value of plums, pollination, tree structure and pruning practices, and rootstock selection. The content below was added in 2018. I have updated and revised some of this 2018 material in a 2023 review that you will find here. Since I have not fully integrated the 2018 material with the 2023 review, it is worthwhile to both continue down to the sections below and read the 2023 reivew.
Why I Raise Plums Plums are a fall-back crop for me. I would prefer apricots and peaches. But that would require a perfect world where it never frosts after the apricots bloom and no pests or diseases ever harass my peach crop and the trees enjoy a long life. Since I live in the north and can’t be free of late frosts terrorizing my apricot blooms or pests and diseases shortening the life of my peaches, I grow plums. To be clear, I do raise apricots and peaches, but I don’t depend on them because some years they disappoint. Plums don’t disappoint. With plums I know I will at least get a partial crop even if we get our predictable late spring frost because, maybe since my orchard is still quite young, pests and diseases haven’t encroached very much on my plum orchard. I really ought not to be so negative as to suggest that plums are a second best. They have excellent nutritional characteristics that ought to push them ahead of my favorites, apricots and peaches. In addition to being a source of vitamin C that contributes to iron uptake, plums are high in potassium, iron, soluble fiber, and a host of other nutrients.
Variety Selection Considerations for Backyard Plum Orchard This article focuses on plum varieties for the backyard orchard. There are certain distinctives that set off a backyard orchard from a commercial orchard. First, usually for a backyard orchard one selects varieties for their taste, and not for their ability to withstand bruising associated with shipping to market (an important consideration when selecting varieties for a commercial orchard). It is desirable for plums in a backyard orchard to ripen over time and have multiple pickings over several days or weeks (also undesirable for a commercial orchard). It is also desirable in a home orchard to have a variety of trees that span the fruit growing season (i.e., early, mid-season, and late varieties). Since space is usually a consideration for the backyard orchard, one might select size-controlling rootstock (which lessens yield in a commercial operation) or consider grafting and budding as a way to have multiple varieties on the same rootstock, and thus conserve space. This usually involves the need to develop grafting and budding skills and locating sources for varieties of scions. It is easy to see that the criteria for selection of plum varieties for a home orchard and a commercial orchard can be quite different. If you have space limitations but still want diversity in your plum orchard you can obtain scion wood locally from friends and neighbors, through the Spokane Area Propagation Fair (see info about this elsewhere on this website) or through a scion wood provider such as Purvis Orchard & Nursery 1568 Hill Road, Homedale, ID 83628-3517, (209)407-6781.
Evaluation of Varieties Early Season. Among the early varieties, the best, to my taste, are the Methley and the Oblinaja (both are early blooming Japanese plums that handle spring frosts very well). My wife values their deep purple hue, believing they are especially rich in anthocyanins, and chooses them for juicing to add to the purple juice she compiles and cans every fall. They also can and dry well. Although it is nice to have an early plum, in my mind, their taste is just not just quite in the same league as the best of the mid-season and late-season plums. I do also have both Early Golden and Early Laxton (which are actually earlier than either the Methley or Oblinaja), but I am top working them to other more desirable varieties and leaving only a couple of limbs of each for pollination, because they just don’t measure up in flavor. Mid-Season. There are 8 excellent mid-season plums on my short list (out of a pool of more than 25 candidates). The two earliest of the mid-season varieties are Monsieur Hatif and Ouillins (also known as Oullins Gage, Oullins Golden Gage, and Reine Claude d’Oullins). These are followed by Gras Romanesc, Mount Royal, and Luisa. The later mid-season varieties of merit include Bavey’s Green Gage, Kirk’s Blue, and Victory. It is hard for me to pick a winner among these-I would grow all 8 and enjoy every one of them. But there is one that really stands out among those 8, the Luisa. The Luisa, a large, sweet, juicy fruit, is the only Japanese plum in this group of 8 (all the others are European plums) and was discovered as a chance seedling in the back yard of a house on Nelson Street in Hamilton, New Zealand (so no one knows its parentage). Its shape is so distinctive that in New Zealand and Australia plums with this shape are labeled the “Luisa type.” It is very popular in New Zealand and Australia, but is not currently propagated by a commercial nursery in the U.S. I will have Luisa scion wood available at the Spokane Area Propagation Fair. Late Season. Although it is hard to beat those mid-season varieties in flavor and sweetness, there are also some good picks among the 20 or so late season varieties that I am growing. Making the transition between mid-season and late season, my favorites are Castleton, Elma’s Special (from Cloud Mountains Nursery and thought to be the Sanctus Hubertus), and Petite d’Agen (French Prune). And later in the later season I especially like the Coe’s Golden Drop and the President. I had my eye on the Shropshire Damson, a really late season variety, as a tree I would do a major top-work on this year because I’m not a fan of tart, at which the Damson excels (in all fairness it is a go-to variety for people making plum jam or chutney). However, if you let the frost work on those little buggers they become edible in late November. I had good eating on these during Thanksgiving week a couple of different years. A note on “best” plums: There are several key characteristic on which plums can be evaluated (e.g., cold hardiness, typical yield level, fertility, stone cling, flavor style, color of flesh or skin, etc.). In our climate here in Eastern Washington our plum varieties cropped well, indicating adequate resistance to late frosts and adequate fertility with wild bees as pollinators. Stone cling characteristics varied but were not deal-breakers. To make my short list (best in season) the plum had to taste good to me, my wife, and a few friends that came by throughout the plum season to see what was new in our home orchard. Although “tasting good” is admittedly subjective, it did have three components for all of us and we were in substantial agreement on which would be “must have” varieties. The plum had to first, have flavor, second, have sweetness, and third, have at least a little juice.
Pollination Here are the major pollination axioms for European and Japanese plums: Although a Japanese plum (and hybrids) will most likely need another Japanese plum blooming at about the same as a pollinator, some are self-fruitful. Although a European plum is most likely self-fruitful, some are not (e.g., most Mirabelles) and will require another variety of European plum as a pollinator blooming at about the same time. In general, crops are heavier for self-fruitful varieties if there is a pollinizer available. Pollination is really not an issue for a backyard orchard if you have lots of varieties spread over the early, mid, and late seasons so that there are several available sources of pollen for both European and Japanese plums.
Rootstock for Plums Nurseries do not always specify which root stock are used for their European and Japanese plums. However, if you have a special situation such as very cold winters or very heavy wet soil you might want to give attention to trying to find nursery stock appropriate for your conditions. If you are in Zone 3 or colder you will want to especially consider plums on either Krymsk 1, a semi-dwarf that is very cold hardy, or Prunus americana, producing a full-sized cold-hardy tree. If you are in Zone 4 or warmer, you have the options of nursery stock on St. Julian A (most widely used in the UK for plums and very widely used in the US as well); Citation, which produces a semi dwarf tree tolerant of heavy wet soil; Pixy, which produces a dwarf tree; Myrobalan (most widely used for plums in the US) for full-sized trees; Marianna (also full-sized with tolerance for heavy wet soil); and various peach rootstocks (also for full-sized plum trees).
Tree Structure & Pruning Strategies for Plums General Distinctions Between Japanese and European Plums Most Japanese plums (and hybrids) can be approached with pruners in the same way one approaches peaches and apricots. Japanese plums typically set fruit on one-year fruit buds and require vigorous pruning to cope with vigorous annual growth. European plums, on the other hand, tend to be more like apples or pears, with long-lived fruit buds (up to 6 years) and much less annual growth than observed in Japanese plums. Structure Options In general, if you are choosing between the widely used open-center and central leader structures commonly found in commercial orchards you will find that all plums do well as open center trees. However, I have had pretty good success getting European plums to conform to the central leader structure as well. If you don’t want to use a ladder to pick your plums you can simply keep your open-center and central leader trees a little smaller than they might be in a commercial orchard. Since a home orchard is not under the same kinds of constraints that a commercial orchard must deal with, you have a lot more flexibility in tree structure and spacing than might be practical in a commercial operation. You can use Richard Bird’s How To Prune Trees, Shrubs, and Climbers to give you some ideas about keeping trees small so they can be picked without a ladder. Consider especially the fan, bush, and spindle as ways to pack more varieties into the same backyard space. Another strategy is to plant three different plum trees in a large hole and train them out from the center of the hole as if they were the three scaffold limbs on an open-center tree. This unusual practice also places different varieties in close proximity for the added benefit of pollination. Similarly, three varieties could be budded or grafted onto a rootstock and trained as three scaffold limbs of an open-center tree, with the benefit of the proximity of pollinating varieties.
Further Reading My favorite reference book on fruit growing is Michael Phillips’ The Holistic Orchard: Tree Fruits and Berries, The Biological Way. It has an excellent section on plums and covers many other general topics that apply to all fruit trees. When you purchase the book, go ahead and add the DVD, it is worth the extra money.