For nut production, trees spaced 20 m apart. For trees up to 2.3 m tall, dig hole 0.6 m deep and 1 m wide. Place tree at same depth in hole as it stood in nursery and spread out roots well. Fill hole with topsoil and firm down soil. Form a basin around edge of hole and soak soil immediately.
Black walnuts require large quantities of nitrogen and phosphorus.
Do not use during first year, because of danger of injuring roots. In strongly acid soils, apply lime to change pH to 6 or 6.5. Do not over-lime, as this makes zinc in soil unavailable to tree. Soils east of Mississippi River are often deficient in magnesium. Crushed dolomite limestone is used to correct this condition and reduce acidity of soil.