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Bare Root Division
(High Density Production)

Esteban Ordonez, Assistant Manager


The Bare Root Division of Princeton Nurseries operates on 350 acres, most of which is located on the Collins Farm. Each year, 40 acres of this land is required for planting in order to produce 210,000+ bare root shade and ornamental trees and shrubs. These 40 acres are fully harvested after four years. This schedule allows us to rotate crops through the farm and to rest each planted area for a minimum of two years. During this resting period, any fertility or drainage issues are addressed before the area is planted again.

All bare root material produced is used as lining out stock (L.O.S.) for the Princeton Nurseries specimen fields except for a portion of our Ginkgo crop, which is sold as a contract-grown item.

Our Propagation Department supplies all of the understock and seedlings, which are lined out in the High-Density, fields. This material is planted in April and May, depending on ground conditions. All High-Density fields are planted
 
with forty-four foot wide sections to accommodate spray equipment. Row length will vary to accommodate crew access and ease of maintenance. All plantings are grouped according to soil conditions, genus requirements, similarity of spraying requirements and similarities of cultural practices.

The understock and seedlings are planted with a two-row pocket planter. The material is then straightened and the soil around the plant packed. All new plantings are over-row cultivated and manually weeded as needed until a herbicide barrier is established. After the barrier is established, a weekly program of cultivation is maintained between the rows.

Care and development after planting varies greatly depending on variety, rate of growth and harvest size. The following is a brief outline.


SHRUBS:

45,000 – 50,000 units are planted annually. They are spaced on four-foot rows and the plants are spaced twelve inches down the row. We currently are able to plant 10,000 –15,000 units per day. All shrub L.O.S. is from seedlings or rooted cuttings. The shrubs are manually cut back after straightening and subsequent trimmings are done mechanically. On spreading varieties an additional manual pruning may be required. All of these subsequent trimmings are performed when the plants are in soft growth to assure continued growth through the growth season. Trimming runs are made one to four times during the growing season. The “in-ground cycle”, (the amount of time the plant remains in our fields), can vary from one to four years, depending on growth rate.


TREES:

160,000-170,000 units are planted per year. They are spaced on five-foot rows and the plants are spaced eighteen inches down the row. We currently are able to plant 8,000-10,000 units per day. All tree L.O.S. is from seedling, rooted cuttings, tissue culture or grafts.

A few varieties are put directly on stakes due to their sensitivity or growth rates, but most varieties are left to grow unstaked through the first summer.

Budding begins in late summer / early fall. The budding program progresses according to budding technique. T-buds are performed first, (which is less than 5% of the budding), followed by chip budding. The budding program takes seven weeks to complete. After budding is completed, the plants are undisturbed until January when all the understock growth six inches above the budding is removed with a corn chopper.

The following spring, the remaining six inches of understock above the bud union is removed. Grow-straight spikes are set next to the bud to guide the emerging shoots into a trunk. The grow-straights are removed after the shoots grow six to eight inches, and they are replaced with fiberglass or steel stakes. Once on the stakes, the trees are maintained and pruned to maintain a 50/50 ratio of head to trunk. The whips are tied to the stake weekly or as needed to maintain a straight trunk.

In the fall, the trees are topped to encourage vigorous branching the next spring. In the second spring, a bud single shoot near the point at which the tree was topped will be taped upward to develop a central leader. The trees will be pruned throughout the spring and summer to maintain the 50/50 ratio.

In the final fall of the in-ground cycle, the trees will be evaluated and allocated to our Container or Specimen divisions. The trees are then harvested and field sorted by grade, and by the division to which the product is allocated. The product is immediately sent to our one-acre storage facility for a final inspection and grading. It is then stored at 38º refrigeration and 95% humidity until planting.

The above is a brief synopsis of the in-ground bare root cycle. Production can vary greatly depending on rate of growth and our finished size requirements.
 

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Last Updated:  December 20, 2006 03:02 PM