Success or failure of Christmas tree plantings depends to a great extent on the quality of planting stock used. Economizing through use of lower priced seedlings may not be wise. Such trees are often smaller and less vigorous, and their use can result in poor survival and slower growth.
Seedlings are usually raised from seed in nursery seedbeds. They are sometimes transplanted to other beds to allow more room for both shoot and root development. Seedling age is designated by two numbers connected with a hyphen. The first number designates the number of years the tree was raised in the original seedbed; the second figure indicates the additional years in a transplant bed. Thus, a 2-0 Scotch pine seedling would be one grown for two years in the original seedbed and not transplanted. A 2-2 Fraser fir transplant would be one grown for two years in the original seedbed and an additional two years in a transplant bed.
Because the development of planting stock varies greatly among species, among nurseries and from one season to another in the same nursery, age alone may not be a reliable indicator of planting stock quality. Quality should be judged mainly on the basis of size and balance. Stem caliper and length and weight of shoots compared to length and weight of roots are probably the best criteria for judging seedling quality (Fig. 19). Seedlings should be a minimum of 6 inches and preferably 9 inches in height. Maximum height varies but should not exceed that which provides a well balanced seedling still convenient for machine or hand planting. In most instances this is no more than 12 inches.
| Fig. 19: Seedlings and transplants. L. to R., 1) 2-1 white pine; 2) good quality 2-0 white pine, 3) poor quality 2-0 white pine; 4) 2-0 Scotch pine; 5) 2-2 Fraser fir; 6) 3-0 Fraser fir; 7) 4-0 Fraser fir, grown in dense seedbed; 8) 3-3 Douglas fir; 9) 3-2 Douglas-fir and 10) 3-0 Douglas-fir. |
For pines commonly planted in Ohio, the above criteria can usually be met with 2-0 or sometimes 3-0 seedlings. Transplants are usually not needed. For spruces, firs and Douglas-fir, three or more years are usually needed to produce high quality planting stock. In many, if not most, instances (depending on species, nursery, season, etc.), transplanted stock (2-1, 2-2, 3-1, 3-2, etc.) is preferred.
In recent years, there has been increasing interest in use of "containerized" seedlings in Christmas tree plantings. Seedlings are grown from seed in small containers. These seedlings, with root systems intact and never out of contact with the rooting medium, are out-planted. Such seedlings have a number of potential advantages. Because these trees do not have to regenerate new root systems, survival and early growth may be better than that of bare-rooted seedlings or transplants. Additionally, soil moisture conditions following planting may not be as critical, and it may be possible to plant successfully later in the spring. Because of faster, more uniform growth, it may also be possible to grow trees to a merchantable size sooner and to harvest all trees in a plantation in fewer years.
As with conventional seedlings or transplants, quality of container-grown seedlings varies. Age criteria discussed previously do not apply because hardy containerized seedlings can often be grown in a year or less. However, guidelines based on size and/or balance between tops and roots are probably still appropriate. Seedlings can be grown in containers having a variety of sizes and shapes (Fig. 20). Tops and roots must be large enough and in balance to provide seedlings that can establish themselves and compete successfully in the field.
| Fig. 20: Seedlings grown in a few of many different types of containers. L. to R., 1) Douglas-fir; 2) Colorado spruce; 3) Fraser fir; 4) white pine and 5) Douglas-fir. |
Cost of container grown trees is greater than that for seedlings, and it may be higher than that for transplants. This additional cost should be justified for establishment of most spruces, true firs and Douglas-fir. It may not be justified for the pines on most planting sites.