Growing Fruit Trees in Maine - Planting and Early Care
Planting in a good site can extend the lifespan of trees and enhance their ability to bear fruit. Soil depth, soil drainage, the potential for spring frost, and the amount of sunlight are important things to consider when selecting a site.
Avoid planting in low spots at the bottom of hills. Cold air settles in low spots, called “frost pockets,” increasing the chance that a freeze will kill flowers during bloom or that severely cold temperatures will kill trees in midwinter. Sites that are surrounded by woodlots prevent cold air from moving out of the orchard and may have problems with winter injury and frost. Sites with good air drainage are typically located at higher elevations on sloping land and are not surrounded by dense stands of trees.
Fruit trees are most productive when in full sun. In order for the tree to form flower buds and grow fruit, its foliage needs exposure to sunlight. Trees planted in full or partial shade will not flower or fruit as much as trees in full sun.
Trees are tolerant of a wide range of soil types, but need a minimum of 18 inches of soil. Many areas in Maine have shallow soil. Fruit trees planted in these areas are typically small or stunted and prone to leaning or falling over.
Soil pH should be in the range of 6.0 to 7.0. When the soil pH is below 5.5, trees will grow poorly. A soil test can be done before planting to determine whether the pH needs to be adjusted. Adjusting the pH with lime is much easier before trees are planted. A soil test can also determine if nutrients are deficient. Nutrients that are lacking can be tilled into the soil before planting. Most soils in Maine contain sufficient fertility for fruit trees, but soil pH is too low in areas where blueberries thrive.
All fruit trees should be planted in well drained soil since flooding favors root rot and asphyxiation. Fruit trees are very sensitive to flooding and can be killed by long periods in water logged soil.
When planting a tree, dig a hole wide enough to allow the root system to fit without the roots wrapping around the edge. The hole should be deep enough to allow the tree to be planted with the graft union just above the soil line. Prune back broken or severely kinked roots. Dwarf and semidwarf trees should be planted with the graft union one to three inches above the soil. If the graft union is planted below the soil, roots will form on the trunk above the graft union, and the tree will be a full sized tree rather than dwarf or semidwarf.
Put only soil back in the planting hole. Adding fertilizer to the planting hole can burn the roots and stunt the tree. Compost and other fertilizers should be tilled into the soil before planting so that they are thoroughly mixed with soil. Gently tamp the soil in the hole to remove air pockets.
The trees should be watered after planting with two to five gallons per tree, added slowly so that the water soaks into the soil. When rainfall is insufficient, each tree can be watered at a rate of five gallons per week. Newly planted trees require water when less than an inch of rain falls each week. However, avoid over-watering since the roots are very sensitive to flooding.
Fruit trees can be pruned at planting to develop the shape of the tree. After this initial pruning, they should be pruned as little as possible until they reach full production, generally six to ten years after planting. Heavily pruned trees remain in an unfruitful state longer than lightly pruned trees.
At planting, remove branches on an apple tree that are within 30 inches of the soil since they are too low to the ground and will impede lawn care. On the main trunk, select four strong branches which will become the lower limbs and prune off the rest. Leave the central trunk unpruned. Ideally, branches should be spaced evenly in a spiral around the trunk, but this does not always happen. Select branches that are oriented somewhat horizontally rather than growing upright since they bear fruit more quickly than upright branches. They should be smaller in diameter than the main trunk. Prune off shoot tips that are dead. There are many ways to prune an apple tree, but the method suggested in the picture below (left) is preferred for developing the central leader training system that is used in many orchards.
Pears and stone fruit can be pruned to develop a vase shape. To do this, prune back the primary upright branch leaving four or five lateral branches. Select strong branches with wide angles from the main trunk. The side branches do not need to be pruned back unless the tips are dead.
To encourage strong tree growth, remove weeds growing under the tree. Weeds compete for water and nutrients, and create problems with trunk boring insects and rodents that feed on bark. Bark or wood chip mulch can be used to inhibit weeds. Avoid straw or fabric mulch since they favor root rot and encourage voles, or mice-like rodents which feed on the lower trunk. When herbicides are used to control weeds, avoid contacting the trunks of young trees, since many herbicides can be absorbed through the thin bark and harm the tree. Allow groundcover to grow back in late summer to insulate the soil from freezing temperatures in winter.