Successful forest regeneration is crucial for sustainable forest management. In boreal contexts, plantation forestry is notably used when natural regeneration is insufficient after harvesting or wildfires, but planted seedlings face various stresses on harvested sites, jeopardizing their survival and growth. Limited access to water, nutrients and light, plus exposure to pests, and diseases contribute to these stresses. Mechanical site preparation, disturbing the organic layer and upper mineral soil through techniques such as discing, mounding or inverting, is commonly used to mitigate post-planting stress. However, climate change, social interest in forest management, and the need to procure diverse ecosystem services require precise silviculture practices tailored to regional and local objectives. Our empirical research in boreal ecosystems of North America and Scandinavia reveals intricate interactions affecting seedling establishment after reforestation. For instance, in boreal Quebec, Canada, successful conifer seedling establishment depends on regional precipitation, temperature, and interactions with soil characteristics and microsite conditions. In Sweden, planting position within scarified sites significantly influences conifer seedling survival, but effects vary with soil moisture. Long-term silviculture studies also demonstrate the importance of early treatments for stand productivity. For example, mechanical site preparation significantly enhances seedling growth and survival, impacting sapling growth even after 18 years in boreal Quebec. We have observed that seedlings planted in scarified plots show improved water use efficiency compared to control plots. Also, we have shown that site preparation effects on standing volume and density persist for at least 30 years in Sweden. In conclusion, our empirical studies with Pinus and Picea species across multiple sites in Canada and Sweden highlight the absence of a universal solution for regeneration success in boreal ecosystems. Forest managers and decision-makers must recognize these complex interactions and support further international research collaborations. The success of large-scale forest landscape restoration and reforestation programs depends on implementing regionally tailored silviculture prescriptions based on an understanding of the mechanisms driving seedling responses.