A Complete Guide to Root-Raising Methods and Techniques for Stump Bonsai

  To enhance the artistic value and appreciation appeal of stump bonsai, the roots are generally given root-raising treatment, so that a portion of the powerfully and steadily shaped roots at the base is exposed on the surface of the pot, giving people an aesthetic mood of ancient ruggedness and majestic wonder.

  Root-raising methods usually include the deep-pot high-planting mounding method, the deep-pot flat-planting water-washing method, and the bucket- or basket-shaped sand or sand-and-gravel root-cultivation method. The deep-pot high-planting root-raising method is to plant the stump in a pot, pile soil around the roots so that the base of the stump is higher than the pot rim but not exposed, and wait for the stump to become established and survive. Then, year by year, use a bamboo stick to dig out the mounded soil from top to bottom, exposing the roots extensively, and finally, after the shape is set, repot it into a shallow pot. In the deep-pot flat-planting water-washing method, the stump is planted deep in the pot, and after it survives, each time water is poured, the water flow is deliberately made slightly stronger to wash against the base of the stump, causing the soil to fall away and the roots to gradually become exposed; then, when repotting, the thick roots can be exposed.

  The bucket- or basket-shaped sand or sand-and-gravel root-cultivation method uses a bottomless wooden bucket or bottomless basket to enclose the stump, filling it with river sand or sand mixed with small pebbles and frequently pouring water and fertilizer into the bucket or basket. When the stump's roots have survived and grown deep into the soil above and below the sand, gradually scrape away the sand and gravel from top to bottom in several stages, with each interval lasting half a year or one year. Finally, remove the bucket or basket to expose the roots, then plant it in a suitable pot. Alternatively, the tree roots can be buried directly in the ground with ridges mounded with soil, and year by year the ridges are removed and the soil scraped away, gradually exposing the roots.

  In nature, some old trees by streams and ravines in deep mountains and ancient forests have their roots often exposed on the ground because the soil has been washed away by water, coiling like dragon claws, which is very peculiar. To enable stump bonsai to also produce this form and improve the ornamental effect, the root-raising method can be used to achieve this goal.

  1. Deep-pot high-planting mounding root-raising method

  First plant the stump in a deep pot so that its main root and lateral roots rise above the pot surface, then mound soil around the roots into a steamed-bun shape so that the roots are not exposed. After one year, use a small rake to scrape away the surface soil layer by layer from top to bottom. After each layer is scraped away, wait half a year to one year before scraping the next layer, so that the tree roots gradually become exposed above the soil surface, avoiding damage to the tender root tissues from sudden exposure. After 2-3 years, combine this with repotting and raise the roots upward year by year, so that the tree roots become exposed.

  2. Cylinder sand-cultivation root-raising method

  Choose a cylinder 40-50 cm deep, fill the lower part of the cylinder with 10-20 cm of culture soil, then plant into the cylinder a stump seedling of a tree species that readily produces lateral roots and adventitious roots, fill the cylinder with river sand, and strengthen fertilizer and water management. After the stump roots have grown in the cylinder and extended into the culture soil layer, gradually dig out the river sand above in 3-5 stages. The interval between each sand removal is half a year or one year. After the roots have grown well, the stump can be taken out of the cylinder and planted in a shallow pot. When planting, give it appropriate trimming and shaping so that the roots are exposed on the pot surface.

  3. Deep-pot flat-planting water-washing root-raising method

  Plant the stump deeply, with the roots preferably not exposed on the pot surface. After planting, the plant's root system continuously extends deeper. After a period of maintenance, each time you water, raise the watering can so that the water washes against the roots, gradually washing away the soil around the roots and exposing the roots. Then, in combination with repotting, raise the cultivation position of the roots, so that the exposed portion of the roots gradually increases and their shape gradually becomes more perfect for viewing.