When deciding how to design a new orchard there are several questions growers should ask prior to planting trees. The answers to these questions will guide decision making about what size trees are desirable, how many trees to plant, how trees, rows and alleys should be spaced or oriented and ultimately lead growers to an orchard layout that will fit their goals and desires for producing apples. For general information on establishing an orchard visit WSU Tree Fruit site.
What are your goals for growing apples?
Knowing what your goals are for growing apples is an important place to start in determining how your orchard will be designed. Do you want standard size trees spaced 20 feet apart to provide a lasting source of apples and romance for generations to come? Or, do you want to see quick returns on your investment by planting a high-density orchard that likely will be replaced in 15-20 years? Do you want to grow mostly dessert apples or are you focused on producing cider apples? There are no correct answers, but knowing the answers will allow you to determine what rootstock and cultivars are appropriate for your goals and how your orchard should be designed in terms of tree density and training system to achieve these goals. These goals and desires must also be balanced with what consumer desires are for your final product.
How many trees can you manage?
While you might have 40 acres of good ground to plant an orchard it is important to be realistic about how that orchard will be maintained and more importantly who will maintain it. Talk to any Montana fruit grower and they will tell you labor is hard to come by and more often than not they are pruning, spraying and harvesting their orchards with little additional help. Understanding what one person (or a family) can reasonably manage is important when determining how large of an orchard can be planted. This is a difficult number to come up with as the efficiency of orchard management will depend on tree density, equipment and grower skill among other factors. In general, 10 acres is considered an efficient size orchard that can be managed for viable commercial production with minimal hired help (University of Minnesota, 2018). As scale increases so will efficiency but growers must keep in mind additional labor will be needed requiring management attention, that is if it is even available.
How do you want to manage your orchard?
Whether or not you want to manage your orchard organically or with conventional measures is an important decision to make prior to planting trees. In addition to personal preferences, what the market desires and the price of conventional vs organic fruit may influence this decision. According to Montana food distributors, the demand for organic fruit is higher than for conventionally grown local fruit. It also demands a higher price, but often producing organic fruit comes at a higher price as well. Other considerations include weed, pest and disease pressure and available options for controlling these issues. For example, an orchard site with several difficult to control perennial weeds such as quack grass and Canada thistle, might be better served to deal with these issues using herbicides when the orchard is being established and delay certification until later in production to give young trees a chance to compete. To learn more about the organic certification process in Montana visit the Montana Department of Agriculture's Organic Program website. WSU also has several resources for growers considering or practicing organic management.
Choosing a Training System
There are several training system options used around the world for producing apples from the old-fashioned standard trees planted at 50 trees per acre to the modern high density super tall spindle planted to well over 1000 trees per acre. A general idea of tree spacing, densities, years to bear fruit and other information about common training systems can be found in Figure 1. Which system a grower chooses will again depend on their goals. If commercial production is the focus, research has shown that higher density plantings equate to quicker and higher yields over the life-time of the orchard (Fig. 2). While these high-density systems when managed well are more efficient, produce higher quality fruit and yield higher profits, initial upfront costs per acre for installation are much higher as they require trellises and more trees are planted per acre. In addition these systems require skilled management to train the trees and manage them for pests and diseases.
Orchard Floor Management Systems
Which orchard floor management system is selected will depend largely on the training system, rootstock, overall management strategy and site. Research has shown that vegetation in rows can compete with trees for water and nutrients resulting in lower yields and smaller fruit, particularly early on (Atucha, et al. 2011; Hoagland, et al. 2008; Merwin and Ray, 1997; Merwin and Stiles 1994). However, depending on your site's soil, slope, aspect and other features, some sort of cover crop can be important at least in alleys to protect soil from erosion, compaction and provide equipment access to the orchard under wet conditions. This article from the Intermountain Tree Fruit Production Guide offers a good comparison of the advantages and disadvantages of various ground cover systems.
The type of vegetation selected for use in alleys or the entire orchard floor also depends on orchard design, stie and management. Several options are available from sod forming grasses to legumes with various advantages and disadvantages that should be considered. For example, while legumes might increase nitrogen, the availability and timing of this nitrogen can not be controlled and can result in increased susceptibility of trees to winter injury or fire blight. Some legumes have also been reported to attract rodents that feed on thier roots. If competition with trees is of particular concern, choosing a shallow rooted grass that goes dormant during the peak growing season, like hard fescue, might be a good option, however, insect pests like spider mites might find trees a tastier option in situations where cover crops are dry and trees are succulent. For more information on choosing vegetation for orchard floor cover visit WSU's Orchard Floor Management and The Intermountain Tree Fruit Production Guides Cover Crop pages.
Row Spacing and Orientation
Once you have determined how you want your orchard to look there are a few basic rules of thumb that can be applied to make your orchard more successful. Orchards are organized into rows and alleys with spacing between trees in rows and between rows dependent on rootstock and tree height. Ideally rows are oriented N/S to capture the most sunlight through the growing season. The distance between rows can be determined based on the mature height of trees. At the northern latitude of most Montana orchard sites, rows should be approximately 90% of tree mature tree height. For example if trees will be trained to no higher than 9 ft, rows should be spaced 10ft apart (Ontario Apple Growers, 2015). If the orchard is located on a slope this should be increased one to two feet to reduce potential for shading.
Shading, however, is not the only consideration in determining row spacing and orientation. The size of equipment used to manage the orchard should also be considered, particularly when the end of a row is reached and equipment must turn around. This turn around space needs to be accounted for at the end of rows and between obstacles like fencing or irrigation lines. The length of rows should also be kept to under 500 ft to maximize efficiency within the orchard.
Spacing of trees will again depend on rootstock, tree density and management system. Cultivar, rootstock and soil induced vigor should also be considered when determining in row tree spacing particularly for high density plantings. Trees and sites with greater vigor should be planted further apart (~4ft) as oppose to less vigorous trees on poor soils which can be planted closer together (~3ft) (Hoying, et al.).