The invention belongs to 
plant nutritious soil and a preparation method thereof and particularly relates to flower nutritious soil and a preparation method thereof. The flower nutritious soil contains the components of 
biomass water-retaining agent, turf, sapropel, black soil, corn 
straw, 
perlite, meerschaum, deer 
feces, fine sand, 
inorganic fertilizer, and the like and is processed by the steps of 
raw material selection, crushing, screening, disinfection, mixing, 
pH regulation and the like. By adopting the method of mixing organic materials and 
inorganic materials, the flow nutritious soil has the advantages of reasonable and loosened structure, complete nutrients, stable property, easily obtained raw materials, easy 
processing and low cost. In addition, the 
biomass water-retaining agent contained in the flow nutritious soil is a novel, multifunctional and natural macromoleclar 
polymer and has a three-dimensional space reticular structure, not only can absorb water and 
fertilizer, but also can retain water and 
fertilizer, and. the water absorbing capacity of the flower nutritious soil is more than 1000 times the weight thereof, a small reservoir of water and 
fertilizer is formed in the soil, and the water and the fertilizer are slowly released, thereby the flow nutritious soil has the functions of saving both water and fertilizer. The invention can be used for growing seedlings and planning seedlings.