Tree fruits differ in whether a lone tree can set a crop
Tree fruits differ in whether a lone tree can set a crop. Apples and most European pears are self-unfruitful. One cultivar alone will not set a normal crop, so plant at least two different cultivars whose bloom periods overlap. For apple, a flowering crabapple in bloom at the same time also works. European plums are partially to entirely self-fruitful, and a second European plum cultivar makes fruit set reliable. Japanese and hybrid plums will not cross-pollinate them. Peaches and sour cherries are self-fruitful and may be planted alone. Partner trees must stand near each other. The published distances are within 50 to 100 feet, and 300 feet at most.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
A self-unfruitful tree will not set a normal crop from its own pollen or the pollen of another tree of the same cultivar; it needs pollen from a genetically different, compatible cultivar, carried by bees while both trees are in bloom. That is why the partner must be a different cultivar, must bloom at the same time, and must stand within a bee's working range. It is also why a self-fruitful species like peach or sour cherry, whose own pollen sets fruit, bears alone.
What to do about it
Check the pollination requirement before buying. For apple and pear, plant two different cultivars with overlapping bloom. Early- and late-blooming cultivars may miss each other, and for apple a flowering crabapple that blooms at the same time also serves. For European plum, pair with a second European plum cultivar. A Japanese or hybrid plum won't do. Site partner trees close together, within 50 to 100 feet where you can and within 300 feet at most. A peach or sour cherry needs no partner.
How much it matters: No figure is added here. The magnitude is the sources': a self-unfruitful tree alone 'will not set a normal crop' (apples set at most a small crop on their own pollen), and the two planting distances (within 50 to 100 feet; within 300 feet) are both published figures, both carried, neither chosen. Because cultivar choice at planting is the gardener's own decision and the app cannot see what grows in neighboring yards, the rule only advises.
The evidence
Evidence: checked against 3 sources in the research-based literature.
The 3 sources
A tree of a self un- fruitful variety should have a pollinator tree planted within 300 feet
Fruit trees that require two different varieties for pollination should be planted within 50 to 100 feet of one another to ensure a good fruit set
Apple: Cross-pollination is always needed to produce adequate fruit crop
Plants it applies to
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Wording made clearer
- Added to the rules
Cite this page
Milpa Gardens. "Tree fruits differ in whether a lone tree can set a crop. Apples and most European pears are self-unfruitful. One cultivar alone will not set a normal crop, so plant at least two different cultivars whose bloom periods overlap. For apple, a flowering crabapple in bloom at the same time also works. European plums are partially to entirely self-fruitful, and a second European plum cultivar makes fruit set reliable. Japanese and hybrid plums will not cross-pollinate them. Peaches and sour cherries are self-fruitful and may be planted alone. Partner trees must stand near each other. The published distances are within 50 to 100 feet, and 300 feet at most." Evidence grade: Promising. https://milpa.garden/rules/tree-fruits-differ-whether-lone-tree-can/
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- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
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- The mechanism is named and the literature backs it. A few questions are still open.
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