Selection of the orchard planting site is the most important decision an apple
grower will face in maintaining the profitability and sustainability of the
operation. Somewhat poor soils can be amended or drained, but a truly bad site,
especially if waterlogged or frost prone, will plague the grower until the
orchard eventually is abandoned or pulled out. Remember that the best site
for your future orchard may not be the land you presently own! Important
site considerations include:
Soil drainage. The ability for the soil to drain excess
moisture is the most important consideration in selecting an orchard site.
Trees planted on wet sites will have problems with root and trunk rots,
nutrient imbalance, poor vigor, and anchorage issues causing them to tip or
fall over under a wind or cropload. Wet soils can be tile drained to remove
excess water but a truly hydric (wetland) soil will never be a good base for
an orchard. Use a backhoe to dig holes 5 to 7 feet deep so that the soil
profile can be examined. Poorly drained soils often have horizontal layers
of light colored material that indicate oxidation of minerals due to excess
Air and frost drainage. Orchards tend to be located on
gentle upland slopes or plateaus, or very close to large bodies of water
such as Lake Champlain. Relative elevation allows cold or moist air to drain
away from the planting in a frost event, while large water bodies moderate
temperature by releasing stored heat or cold to the surrounding environment.
A 4% to 8% slope is ideal, while a slope steeper than 10%may
make it difficult to operate machinery. Avoid areas at the bottom of the
hill where cold air settles and frost pockets form.
Soil depth. Orchards require deep soils with at least
30 inches to a restrictive feature such as bedrock, hardpan, or water table.
This soil depth is required tom provide good tree anchorage and an adequate
aerated zone for root function.
Soil pH. Apples prefer a slightly acid soil of pH
6.0-6.5. Many soils in Vermont are naturally acidic and will respond to
liming, but extensive pH adjustment (pH below 5.8) must be done prior to
planting. Information on adjustment of acidic soils with lime can be
found in the New England Tree Fruit Management guide, available from the
Cooperative Extension Service of each New England state. Some orchard sites,
especially in the Champlain Valley, are located on natural limestone
bedrock, and may have naturally high pH. These soils can be acidified
with granular sulfur, but the effect is more temporary than treating acid
soils with lime and the grower should carefully manage micronutrient levels
in the trees because many minerals become less available to the plants under
Annual minimum temperatures. Apple production can be
limited by the absolute minimum temperatures experienced at a particular
site due to damage to or death of trees after experiencing cold damage. This
explains the lack of orchards in northeastern and high elevation parts of
the state. Areas that regularly experience -25°
F are risky for orchard production. Cold sites should be planted to hardy
varieties grafted onto hardy rootstocks including the Budagovsky series,
MM.11, and seedling stock in extreme cases.
Annual growing degree days. Apples require a certain
amount of acquired heat units from bloom to harvest to ripen a crop
reliably. Areas with less than135 frost-free days and annual accumulation of
growing degree days (base 50° F) below 2000
should consider shorter-season varieties, with no apple ripening after
Liberty or Empire.
Slope orientation. Within a given area, a south facing
slope receives more sun, thereby warming faster in the spring, while a north
facing slope will be colder, warming up late in the spring. Accumulated heat
units will be very different on the two slopes, which will translate into
changes in orchard performance. For example, and early-blossoming variety
may be avoided on a south slope that receives spring frosts to avoid having
too much tender tissue subject to damaging weather.
Of all the decisions you make in establishing your orchard,
choosing the correct site and location has the greatest long-term impact. An
orchard is a long-term venture; it may be productive for 30 to 75 years, and in
some instances, even longer. It is necessary to make educated and well informed
decisions in selecting the location and site of your future orchard.
Selected links that provide weather and soils data for
USDA Web Soil Survey
NOAA Burlington VT
Searchable NOAA Online Weather Data
Soil preparation should be done at least by the summer before planting. This
is the time to do a soil test to determine the needs of your soil and to
provide time to correct any deficiencies and improve soil fertility.
Correcting the soil pH is one of the most effective nutrient management
practices to improve fertility in an apple orchard. Try to maintain the soil
pH in the range of 6.0 for the subsoil to 6.5 for the topsoil because the pH
influences the availability of the various elements to the plant. For
example, as the soil pH becomes acidic (pH <5.5), the phosphorous in the
soil becomes unavailable to the plant. It does not matter if there is an
adequate amount of phosphorous in the soil; the roots are unable to uptake
it, or some elements become toxic at high or low pH. Correcting the soil pH
needs to be done before planting because once the trees are in place, it is
very difficult to change it. In regions with acidic soils, lime, preferably
dolomitic for apple orchards, is usually used to raise the pH.
Other ways to improve soil fertility include:
Addition of organic matter
Maintenance of good tilth
Addition of nutrients when needed
Specific orchard site preparation plans are included in the
New England Tree Fruit Management guide, available from the Cooperative
Extension Service of each New England state. Further information on orchard site
preparation can be found in the Penn
State Tree Fruit Management Guide.