Ecology Wind pollinated. Suited to rich bottomlands and fertile hillsides from lower Hudson Valley southward, walnut will grow a few hundred miles outside its natural range, but may not bear nuts. Best suited to deep, rich, slightly acid or neutral soil, with good drainage, but will not succeed on infertile upland soil or on soils with poor drainage. Reliable indicators for suitable land are good stand of white oak and tulip popular, or where corn grows well. Because trees have a deep taproot, they are drought resistant.
Scions develop crowns that bear nuts of their own variety.
As there is little information available to indicate the best cvs for different localities, local nurseries should be consulted. Trees are self-fertile, but the sequence of male and female blooming, called dichogamy, can and often does minimize chances of a tree shedding pollen on its own pistils. In different trees pollen may be shed before receptivity period of female flowers, or at same time, or after pistil receptivity. For greatest possible nut production, plant trees of 2 or more cvs, as different cvs have overlapping pollen-receptivity periods and can pollinate each other. Young plants are best transplanted in early spring, when new roots will grow rapidly to replace those lost in transplanting.