Substrates and potting mix for use in hydroponics, forestry, agriculture and horticulture; organic and synthetic amino-plastic rigid foam for use in hydroponics, forestry, agriculture and horticulture; growing media; structural columns made of plant growing media; planters, panels, seeding trays and other structures made of plant growing media; plant growing media incorporating nutrients, minerals, trace elements, fertilisers and foods for plants; chemicals for use in science, agriculture, horticulture, hydroponics and forestry; nutrients, minerals, trace elements, fertilisers and foods for plants; potting compounds; growth promotors and stimulants for plants