Alternative substrates and substrate stratification in nursery weed management: a comprehensive review

Container nursery production relies heavily on peat-based substrates; however, environmental concerns, rising costs, and increasing weed pressure highlight the need for sustainable alternatives. Weed infestations in container systems result in significant economic losses and are traditionally managed using pre-emergence herbicides and manual labor, both of which present limitations including resistance development and high costs. This review evaluates alternative organic, inorganic, and recycled substrate materials as integrated weed management tools in ornamental container production. Alternative substrates such as rice hulls, coconut coir, compost, pumice, lightweight expanded clay aggregate (LECA), sand, and recycled paper can suppress weeds through multiple mechanisms, including physical barriers, altered nutrient and moisture distribution, allelopathic interactions, and microbial activity. Substrate stratification and strategic fertilizer placement further enhance weed suppression by limiting nutrient access at the surface while promoting crop uptake. Adoption of these substrates is constrained by cost, variability in material performance, and limited ornamental-specific research. This review presents a range of alternative substrates, some of which remain underutilized and insufficiently explored in container production systems. However, their reported physical, chemical, and biological properties suggest strong potential for improving substrate performance and supporting weed management in container-grown crops. The review also provides a strategic framework for integrating substrate redesign with targeted weed management, offering a proactive, sustainable alternative to herbicide-dependent systems by creating an unfavorable microenvironment for weed establishment from the outset.