Evaluation of the most popular annual flowers sold in the United States and Europe indicates low visitation rates by pollinators and large variation among cultivars

Abstract

To better understand how frequently pollinators visit the most popular annuals and the variation among cultivars, we evaluated 3–6 cultivars, each of petunia, impatiens, begonia, geranium, pansy, and New Guinea impatiens. These 6 annuals account for 46.6% of all garden center annual flower sales in the United States. Flower visits by honey bees, bumble bees, syrphids, other Diptera and other Hymenoptera, combined, varied 3 to 10-fold among cultivars within each of the 6 popular annuals. Begonia and impatiens were visited more frequently by pollinators than pansy, petunia, NG impatiens, and geranium. The 4 most visited cultivars, begonia ‘Cocktail Brandy’, begonia ‘Ambassador Rose Blush’, impatiens ‘Accent Coral’, and impatiens ‘Super Elfin XP White’ attracted as many pollinators as a benchmark annual, marigold ‘Alumia Vanilla Cream’, considered as moderately attractive to pollinators. Some conclusions from this research may be helpful for homeowners, landscapers, growers, and breeders. First, the most popular annual flowers are not a good choice for the purpose of attracting and supporting pollinators. However, the large variation among cultivars provides an opportunity to select cultivars that are more attractive to pollinators, particularly for begonia and impatiens. If the most pollinator-visited cultivars of begonia and impatiens are labeled and promoted as such, it would be beneficial to pollinators in urban and suburban landscapes in the USA and Europe, where they comprise 10%–20% of all annual flowers purchased from garden centers.