Walnut trees are tall deciduous trees. The crown of the tree is relatively open under natural growth conditions, and most of them have a natural round head shape. The tree is tall and strong, with dense branches and leaves, well-developed root system, strong adaptability and natural renewal ability, and long life. The tree likes warmth and light, but is afraid of freezing and avoids shade. The branches in the crown are distributed in layers, have strong dryness, mostly grow in a uniaxial manner, and are difficult to branch. In addition, the tree body is not cold-resistant, and immature and poor-quality branches often dry up due to frost damage and stripping. Therefore, saplings take shape slowly. Grafted seedlings of ordinary walnuts bear fruit early, while seedlings of seedlings bear fruit late. When the branches are well managed and strong, they have strong ability to bear fruit continuously. There is an obvious apical advantage in budding, branching, flowering and fruiting. However, during the growth and fruiting process of large perennial branches, the original head often weakens while the lower branches grow stronger and take over the head. They no longer show vertical and apical advantages. As the age of the tree increases, the number of branches increases, the branch angle becomes larger, and the lateral growth of the crown accelerates. This growth trend gradually shifts from the original head of the mother branch to the lower back and side branches, resulting in a more obvious "inverted pull" phenomenon in which the lower back branches are dominant and long. This is because in the natural growth state of walnut trees, the central trunk often gradually weakens and the main branches slowly weaken. Strengthening is the main reason why tree crowns take on their naturally rounded shape. Due to early apical dominance, large backbone branches often bear fruit in the middle and upper branches and are bare at the lower base. After young seedlings are planted, within 1 to 2 years, the growth of the main root is more than twice as fast as the growth of the above-ground seedling stem. The seedling stem only grows uniaxially with the germination of the terminal bud and extends upward, and rarely branches. After three years of growth, the number of underground horizontal roots and aboveground branches gradually increases, and the growth rate also accelerates. Fruit growers call this rule "first sit down and take root, then stand up and grow trees." After 5 years of age, the vertical growth of the above-ground crown slows down and the horizontal growth accelerates. The main feature is that as the branches increase, the central trunk gradually weakens, and the lateral main branches grow stronger and gradually form the main skeleton of the crown, but the results are not many. After 15 years of age, the crown expands the fastest and the yield gradually increases. If the branches are not fully developed, scorch may occur at the top of the branches. After 20 years of growth, the fruiting period begins. The crown gradually opens, the branches begin to droop, and the tree becomes weaker. However, the volume of the crown continues to expand, the light in the crown is insufficient, the fruiting part gradually moves outward, and the number of scorched tips increases. After 40 years of growth, the canopy became closed, ventilation and light transmission seriously deteriorated. In addition to an increase in the number of scorched shoots, some branches dried up, and the crown began to partially renew. There are many latent buds on the large branches of walnut trees, which are long-lived and easy to germinate into branches, which is very conducive to the renewal and rejuvenation of old trees. The tree body is resistant to pruning and renewal. After natural renewal 3 to 4 times in its life, its lifespan can reach more than 200 years.