A self-incompatible pome fruit's pollen partner has to bloom at the same time and make viable pollen
A self-incompatible pome fruit's pollen partner has to bloom at the same time and make viable pollen. A triploid apple cannot be the pollen source, and a second tree of the same variety is not a second cultivar.
Well established 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
Cross-pollination only works while both cultivars' flowers are open together, so their bloom periods must overlap: early with mid, or mid with late. Early and late can miss each other entirely. A normal cultivar makes viable pollen; a triploid apple, with three sets of chromosomes instead of two, makes little or none and cannot fertilize a partner even though it needs one itself. Two plants of a single variety, including a colored sport of it, are genetically identical, so they reject each other's pollen exactly as a lone tree does.
What to do about it
Pick the second cultivar so its bloom overlaps the first, and do not rely on a triploid apple (Gravenstein, Winesap, Mutsu or Crispin, Jonagold) for pollen. Grow one only beside two other cultivars that pollinate each other. An ornamental crabapple that blooms at the same time will pollinate any apple. Two strains of one variety do not count as two cultivars. The partner does not have to share the bed. Within 50 to 100 feet is close enough for the bees, so a neighbor's tree of a different variety counts. For apple, a crabapple in bloom at the same time does too.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
If one cultivar is to provide pollen for another, their period of bloom should overlap, particularly early bloom.
Most European pears are self-unfruitful. Plant at least two different cultivars.
Plants it applies to · 2
How this rule has changed
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- Wording made clearer
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- Added to the rules
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Milpa Gardens. “A self-incompatible pome fruit's pollen partner has to bloom at the same time and make viable pollen. A triploid apple cannot be the pollen source, and a second tree of the same variety is not a second cultivar.” Evidence grade: Well established. https://milpa.garden/rules/self-incompatible-pome-fruit-s-pollen-partner/
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