Use compost to grow and nourish plants. It contains valuable microbes which convert soil, air and water into nutrients for plants. If you don’t have a compost, you should make one, or just have a compost heap which you turn regularly. If you can’t do a compost, buy from a reputable source; some manures could contain harmful herbicides and residues which will mutate the growth of some plants, particularly tomatoes.
Use leaves, grasses, weeds, crop and flower garden trimmings as well as kitchen parings other than meat scraps (which will attract vermin). Turn every week (the compost, that is) to encourage microbial activity, for a minimum of 90 days to ensure good quality. If you can, use a termperature probe to check temperatures, and turn when temperatures fall. Cover if cold or wet, water when dry.
It should form a ball in your fist, but not be dripping wet. Use it to ‘innoculate’ your planting area and transplant holes.