Blocks were formed from peat or peat‐lite amended with a granulated hydrophilic polymer (Viterra Agri‐gel®, potassium propenoate‐propenamide copolymer) or a binding agent (Natrosol 250 HHR®, hydroxyethyl cellulose). Blocks were subjected to slow‐release (Osmocote®) or solution fertilization and to cyclical or capillary irrigation. Tomato seedling shoot fresh weight was acceptable in peat‐lite blocks irrespective of fertilization or irrigation regime, and in peat blocks irrespective of irrigation regime if provided solution fertilization. Shoot fresh weight increased quadratically with increasing Agri‐gel incorporation rate in peat and peat‐lite blocks receiving solution fertilization, irrespective of irrigation regime. Peat blocks held more water and underwent less expansion with hydra‐tion than peat‐lite blocks. Capillary irrigation resulted in greater block stability than cyclical irrigation. Agri‐gel incorporation in blocks increased block water content and block stability. Natrosol incorporation further enhanced block stability but generally had no effect on tomato shoot growth.