Native plant restoration relies heavily on the use of containers developed for reforestation. The timber industry wanted to grow seedlings that could be successfully used in tree planting without the need for supplementary irrigation. The containers they developed are shaped like narrow tubes. These proved ideal for native plant restoration.
An example of a restoration container is the supercell. It is 1 1/2” in diameter and 8” tall, with a conical base. There are small ribs on the inside of the supercell that stop root swirling, and train them to grow downward.
A tubular container produces a plant with a root ball that is narrow, but deep. The deeper the root system, the closer the roots are to a stable water supply. Soil is moistened by rain from the top down, but it also dries from the top down. The soil near the surface is the most unstable location for providing water to a plant. Go just a few inches down into the soil and the situation improves dramatically.
Along with creating a deep rootball, the tubular container uses a minimum of lateral space, allowing plants to be packed closely together. A rack for supercells and stubbies accommodates 98 plants in a space that is 10” wide by 20” long, or 2 sq. in. per plant. 10 dee pots can be stored in a rack that is 10” wide and 10” deep, or 10 sq. in. per plant. Contrast this with a one gallon container, which uses around 35 sq. in. per plant. This not only allows a small nursery to raise large quantities of plants, it makes it easier for restoration crews to carry plants into the field.
Problems and Disadvantages
It may be difficult to use tubular containers with trees that have coarse, woody root systems. There may not be enough root present to hold the soil mass together. During planting, the soil may fall away, exposing the roots. Roots are the most sensitive part of the plant, and any disturbance of the soil ball may shock or kill the plant. Tubular containers, especially the small sizes, are best used with species that have moderate to fine root systems. This includes some tree and shrub species, but especially herbaceous perennials, grasses, sedges and rushes.
The above ground portions of many plants have significant lateral growth. The tops of the plants may interfere with each other. Plants often kill their neighbors, but this may not be apparent while the plants are in the rack. We can go to a restoration site with an apparently full rack of live plants, only to find later that up to 1/4 of them are dead. We won’t know this until we start to remove them from the rack and reveal the dead ones.
A general problem with small plants is that they are quickly covered by weeds, and become lost. During mowing and weeding, the small plants are accidentally cut down or pulled.
In spite of the potential problems, restoration containers are an excellent choice for use in planting projects.