Growing peaches (Prunus persica) in Maine is a challenging proposition on the whole because the peach tree is tender to the long, cold winters and often will lose its flowers to early spring frosts. Peaches are better grown in warmer areas of New England, such as southern New Hampshire, Connecticut, Rhode Island and central and western Massachusetts. However, as long as the peach tree is a suitable variety and situated well, there is no reason a Maine gardener couldn't be successful in raising peaches in the southernmost reaches of the Pine Tree State.
Peach Growing Areas
Peach trees survive winters that get no colder than -15 degrees F, which correlates to USDA Hardiness Zone 5. Conversely, in order for fruits to develop and reach harvestable size and quality, summers should provide at least 14 days of temperatures above 86 degrees F, corresponding to the American Horticultural Society's heat-zone of 4 or warmer. Combining these factors reveals that the only suitable areas for raising peaches in Maine are in the coastal southwest: south of a line running from Sanford, Auburn and Waterville to Belfast on the western shores of the Penobscot Bay.
Much like peach trees grown in nearby New Hampshire and Massachusetts, any peach trees grown in southern Maine must be grafted upon cold-hardy rootstock for longevity. According to the North Central Region of the USDA's Integrated Pest Management (IPM) Center, peach trees in New England are best grafted on either 'Halford' or 'Lovell' seedling rootstocks. Another cold-hardy rootstock is named 'Siberian C'.
Recommended Peach Varieties
Focus on locating and buying local peach trees from nurseries in the state or from climate-similar regions of New Hampshire or Massachusetts. Recommended peach tree varieties that excel in southern New Hampshire that likely translate well to southernmost Maine include: 'Reliance', 'Redhaven', 'Harbinger' and 'Canadian Harmony'. Nectarine varieties (which are fuzzy skin-lacking peaches) to consider include 'Mericrest' and 'Hardired'.
Siting the Peach Tree
Plant the peach tree in fertile sandy or loamy soil where it will receive at least 8 to 10 hours of uninterrupted sunlight in the growing season. Peach trees will not survive in poorly drained soils. With the winters so cold and springs chilly with the threat of late frosts that can damage the flower buds, the University of New Hampshire recommends planting peach trees on a south-facing hill for added winter warmth as well as to shed the heavy cold air of frost to lower elevations in the garden. While the peach tree is hardy to -15 degrees F, flower buds and blossoms are killed by temperatures as low as 0 to -5 degrees F. If your garden readily receives such cold temperatures in winter, a peach tree may not be a good fruit tree choice whatsoever.
Plant peach trees in spring before their leaves unfurl, such as in mid-April to early May. Space them 12 to 15 feet apart in an orchard setting if more than one tree is grown; peach trees are self-fertile so multiple trees are not necessary for flower pollination and fruit set. Any pruning of branches is done in late April after the flowering season so branch reduction can be modified based on any loss of flowers due to late frosts, according to William Lord of the University of New Hampshire. Peach trees produce their flowers and fruits on the previous year's branch growth, so ensure your tree grows 10 to 12 inches each year. Fertilize trees in early spring with a well-balanced fertilizer product in granular form (such as 10-10-10).