One of the most important steps to fruit and flower production is pollination, but there are a few things you can do to help your petunias on their road to flirting with flowery success. Here are some simple tips for helping identify the pollinator your petunias require.Bees are attracted to certain colors, scents and types of flowers. While petunias do come in colors, like white and yellow, that attract bees, the blooms and petals are not wide enough to provide a good landing area. Bees land on flowers that produce nectar or pollen to take back to the hive. But petunias contain little nectar or pollen, which means they offer little or no value to bees. So, while bees may buzz around petunia blooms because of their bright colors, they do not stay long, especially if the petunia is planted alone in a container or bed.
Although petunias are easy to grow outdoors from transplants, they may prove more challenging for beginning gardeners to start from seed. The advantages of starting petunias indoors are that you have a wider choice of varieties from which to choose, and you can raise large quantities of plants for less money. But it takes 10 to 12 weeks before petunias are big enough to plant out, so they need to be started early (about March first in northern climates). This means there's ample opportunity for problems to develop between seeding and the final product!Two clear candidates for adaptive radiation owing to pollinators are the relatively distantly related Iochroma and Nicotiana, each of which contains flowers of four pollination syndromes (figure 2). The amazing diversity of form and colour in flowers of the Iochroma lineage (Smith & Baum 2006, fig. 3) does not correlate with pollinator shift (Smith et al. 2008a) and, when growing in sympatry, species with quite different flower morphologies share pollinators (Smith et al. 2008b). Thus, in this lineage, floral diversification is not an adaptive response to pollinators, but may instead be due to factors such as selection against nectar robbers or various community-related effects (Smith et al. 2008a). Nicotiana species have a similar wide array of flower types (Knapp et al. 2004). In the widespread, bird-pollinated Nicotiana glauca, Nattero & Cocucci (2007)) correlated geographical variation in floral tube length with bill length in hummingbird communities, suggesting adaptation to pollinators, but observations in the field on pollinator preferences for variable populations of N. glauca showed no such partitioning (Schueller 2007). Species of section Alatae with bird and moth-type flowers asymmetrically shared pollinators, with hawkmoths visiting both floral types (Ippolito et al. 2004); a similar pattern has been shown in Petunia (Lorenz-Lemke et al. 2006). Kaczorowski et al. (2005) have suggested that nectar traits, rather than floral form per se, have shaped pollinator preferences in the Alatae. The bat-pollinated Nicotiana otophora (Vogel 1969) was visited by hawkmoths when in sympatry with the classically moth-pollinated Nicotiana sylvestris (Nattero et al. 2003; figure 2f). Nicotiana attenuata has typical moth flowers, but in a series of elegant field experiments, a complex trade-off between scent and nectar chemistry was shown to mediate pollination by both hawkmoths and hummingbirds, with differences occurring seasonally (Kessler & Baldwin 2006; Kessler et al. 2008). As in the Iochroma lineage, pollinator relationships in Nicotiana are clearly complex and not simply the result of the interaction of floral form and pollinator-mediated selection, but new data on floral form and phylogeny (E. W. McCarthy 2009, personal communication) will shed light on these relationships.
Pollinators are indeed diverse in the Solanaceae, and while floral zygomorphy is more common in the basal grade, it is not only these groups that exhibit great diversity in pollinator syndromes (and indeed in pollinators, see table 1). There is a great deal of homoplasy in pollinator syndrome at the generic level, as evidenced by the equivocal status of deep branches (figure 2). This indicates that at the generic level at least, the Solanaceae have not adaptively radiated in terms of pollinators, but certain clades and/or genera have clearly exploited pollinator space extensively. The genera of the Petunieae have five different pollinator syndromes, and Brunfelsia alone has three (moth, butterfly and bird). In Brunfelsia, the South American species have either moth (e.g. Brunfelsia guianensis) or butterfly (e.g. Brunfelsia grandiflora, figure 1e) flowers, while the Caribbean taxa (thought to be monophyletic by Plowman 1998) are all long-tubed (e.g. Brunfelsia americana) and probably pollinated by sphingid moths, except for the Cuban endemic Brunfelsia cestroides, which has bright red, presumably hummingbird-pollinated flowers. Petunia exhibits a similar range of flower types (Stehmann et al. 2009), and developmental studies on species pairs have revealed the genetics behind these differences (Stuurman et al. 2004; Hoballah et al. 2007; Gübitz et al. 2009). Schizanthus, sister to the rest of the family (Olmstead et al. 2008) and with the most zygomorphic flowers in the family (Knapp 2002), has a range of pollinators (Pérez et al. 2006), and combinations of floral traits related to pollination have been shown to have evolved in a concerted fashion (Pérez et al. 2007). (Source: royalsocietypublishing.org)