<p>Phylogenetic ecology uses phylogenetic patterns to infer ecological community processes. Competition is expected to be stronger between closely related species because of higher niche overlap and facilitation is rarely considered in phylogenetic ecology. So far, there are mixed results as to whether phylogenetic distance is a good proxy for species interactions. Coastal dunes are a harsh environment for plant development with both competition and facilitation but limited understanding of which factors determine each outcome. We evaluated the effect of phylogenetic distance on the outcome of plant interactions on coastal dunes. We also investigated if this effect was modulated by the growth form, the ontogenetic stage of the interacting plants and environmental stress in which the interaction occurred because these are characteristics important to determine the outcome of plant-plant interactions. To achieve this we conducted a meta-analysis, in which we selected studies done in coastal dunes that compared the performance of plants with neighbours and isolated plants. We found that phylogenetic distance did not affect the outcome of plant interactions (163 observations, 25 studies), nor did growth form, or ontogenetic stage, or environmental stress modulate the effect of phylogenetic distance on the interactions outcomes. Therefore, contrary to our expectations, the phylogenetic relatedness is not a good predictor for the outcome of plant-plant interactions in coastal dunes, even when considering growth form, ontogenetic stage and environmental stress. These findings reinforce that determining the outcome of species interactions is a complex task and caution is needed when using proxies to infer it.</p>