Pollination

• Pollination is achieved when pollen is transferred from male stamens of the flower onto the female stigma of a receptive flower. It is most often transferred inadvertently by insects in search of nectar. Within lime trees, stamens are directly adjacent to the stigma, making self-pollination relatively simple. Traditionally, citrus plants have been self-pollinated. However, increasingly more self-incompatible varieties of citrus tree are entering the market. Fertilization challenges posed by this trend are overcome using compatible species cross-pollination.
  
  

Cross-Pollination

• Over the past several decades there have been relatively few studies specifically focused on lime pollination. Research does suggest that self-pollination of limes will produce maximum fruit set. However, cross-pollination is highly correlated with greater fruit retention, increased fruit size and higher seed counts. Basically, pollinated limes are usually larger but with more seeds. Commercially, sweet lime, which is a lemon-lime hybrid, is often successfully inter-planted with grapefruit and sweet orange.
  
  

Parthenocarpic Limes

• Persian limes, also called Tahiti limes, are parthenocarpic, which means that they do not require fertilization to produce fruit. It also means the fruit is seedless when trees are grown in a monoculture. Persian limes planted among other citrus species will receive some cross-pollination. They will likely produce some seeds as a result. Key limes, also called Mexican limes, are not parthenocarpic and are typically quite seedy. Most consumers consider parthenocarpy a desirable trait. Sour-tasting seeds can take away from the citrus flavor of the fruit. Seeds also take up valuable space within the lime.
  
  

Considerations

• Honeybees are an affordable and effective pollinator of citrus plants. For the most part, bees are readily drawn to sweet-smelling, high-nectar-count plants, such as lime trees. Rented beehives are often distributed throughout commercial groves as an additional pollination safeguard. Within the home landscape, lime flowers should self-pollinate either completely on their own or with the assistance of local bee populations. If lime trees are not producing fruit, it is more likely the result of improper care or poor site selection.