Are Jonathan Apples Self-Pollinating?

Like other cultivars, "Jonathan" apple trees (Malus domestica "Jonathan") are sometimes called self-fruitful, but they require nearby pollinators to produce bumper crops of fruit. Grown in U.S. Department of Agriculture plant hardiness zones 3 through 8, "Jonathan" must be cross-pollinated with a different apple cultivar that blooms at the same time. Trees offering sweet, tart, sour or mildly tangy fruit depend on wild bees, honeybees, butterflies and other insects, and sometimes gusty winds and rain to pollinate nearby flowers.

Apples and other fruit trees that can produce flowers and fruits do so in different ways, notes University of Missouri Extension. The term "cross-pollination" means to transfer pollen between species or cultivars. Self-fruitful varieties contain their own pollen. Sterile or self-unfruitful plants may have some but little fruit. Cross-unfruitful varieties, even if they are cross-pollinated, will not produce fruit, nor will planting two inter-sterile trees together. Self-pollination varieties allow pollen to move between similar plants. Facilitators of pollen transfer --- bees, insects and the wind, for example -- are called "pollinators." A plant or tree that produces pollen is a "pollinizer." Compatible plants fertilize one another and pathenocarpic varieties set fruit but do not have seeds.

"Jonathan" apple trees grow about 10 to 25 feet high and wide, thriving in various well-draining soils with pH around 6.5. They need about six to eight hours of daily sunlight and do not tolerate prolonged periods of drought. "Jonathans" are partly self-fertile but to fruit consistently, trees must be planted with similar pollinating cultivars. Many cultivars compatible to "Jonathans" include "McIntosh" (Malus domestica "McIntosh"), grown in USDA zones 4 through 6, "Braeburn" (Malus domestica "Braeburn"), "Cortland" (Malus domestica "Cortland") and "Gala" (Malus domestica "Galan"), all three suitable for USDA zones 4 through 8. Although "Jonathan" and similar apple tree cultivars are considered self-fruitful, they depend on other trees for flowering and fruits. Apple trees must bloom at the same time for flowers to pollinate. "Jonathan" apple trees require a separate cultivar; they cannot pollinate each other.

"Jonathan" apple and other fruit tree blossoms have female and male reproductive organs. Honeybees or wild bees transfer pollen grains from the male’s anthers to the female’s stigma inside the flower. The pollen grains stick to the stigma, germinate, produce a growing tube and then fertilize the female ovary. Seeds develop after the flower is fertilized, allowing fruits to grow. Trees planted more than 100 feet away from each other may deter bees from transferring the pollen grains. Cold temperatures, rain and gusty winds can also affect pollination. Honeybees work best in temperatures above 65 degrees Fahrenheit.

Poor pollination is one reason "Jonathan" apple and other trees may not set fruit, especially if flowers aren’t blooming simultaneously. However, other problems include winter bud and springtime frost damage, lack of soil moisture and nitrogen during flowering, too much or not enough pruning, and insect damage and various types of disease. For successful pollination, fruit trees must grow near others in their own family. For example, cherry (Prunus cerasus) and apple trees planted together will not pollinate each other.