Considerations

• The black walnut seed must endure a stratification period in which temperatures below 40 degrees Fahrenheit loosen the seed coat and initiate sprouting. Seeds lay dormant in the chilly to cold soil for a few months to two or three years before finally germinating.
  
  

Time Frame

• Length of stratification needed for seeds to sprout varies by plant and local geography. In some cases 90 to 120 days of cold stratification lead to germination in soil while some trees' seeds need a longer cold exposure, up to 20 to 31 months. According to the U.S. Forest Service, nuts buried and abandoned by squirrels may need a couple winters of cold exposure to finally germinate.
  
  

Size

• A seedling appears in mid to late spring after the first or second winter following planting. Sow seeds in moist, fertile, organic-rich soil that never becomes soggy. A full sun exposure is also required. The seedling grows up to 36 inches in its first year with a deep, thin taproot.