JARS v53n2 - Modified Nearing Frame Respects Need for Dormancy

Modified Nearing Frame Respects Need for Dormancy
Mark G. Konrad, M.D.
Sewickley, Pennsylvania

An early pioneer method of rooting rhododendrons was the use of the Nearing Frame named after its innovator, Guy Nearing of Mahwah, New Jersey, who patented it in 1932. Historically, it has been a proven mode for rooting cuttings of difficult rhododendrons, especially the large-leaf varieties, and was widely popularized by David Leach and Warren Baldsiefen who recognized the necessity of maximum light without direct sun, high atmospheric humidity, and a porous rooting medium, all of which the Nearing Frame provided. Both Leach and Baldsiefen added hormones to the method. Another less heralded aspect of the Nearing Frame, I feel, is its success in allowing for the natural completion of the dormancy state under highly controlled conditions.

Original Nearing Frame
The original Nearing Frame designed by Guy Nearing consisted of a rooting box constructed of durable wood with wooden flooring allowing for slow drainage of water and projecting beyond the frame to anchor it against wind. The sides, peaking at the front, are also built of wood, and the roof, which slopes from the ground level in the back to the top of the front opening, is made of metal. The frame is oriented so that it faces true north. Soil is back-filled around the outside of the frame. The wood and metal surfaces on the open north end are painted white to reflect light. (For detailed construction plans, see Leach's Rhododendrons of the World .)
The appealing aspects of the method were the low cost, low maintenance, and the ability to cycle through the dormancy period naturally. One disadvantage, however, was the extended period of time needed for rooting. David Leach popularized the method, and I was told by him that Warren Baldsiefen, who died in the early 1970s, had 32 Nearing Frames in use at one time.

Replacement of Nearing Frame
As a result of reduced production costs with plastic greenhouses and the use of bottom heat, the Nearing Frame became less fashionable. The added advantage of using a greenhouse is the accommodation for post chilling following rooting that is necessary for bud break. The so-called "warm method," however, does not eliminate the need to factor in the dormancy state needed for rooting large-leaf rhododendrons.
The use of the Nearing Frame has waxed and waned during the years. I think the main reason for this has been the relative inconvenience in its construction and use. Because of this, I have spent considerable time trying to find ways to make the design more practical. Many variations were discarded, but the search lead to designs which have proven easy to use. With the advent of plastic materials it has become easier to improvise.

Renewed Interest
My renewed interest in a modified Nearing Frame method occurred when I realized its overall simplicity, reduced cost, and low maintenance. The purpose of this article is to offer a re-evaluation of the Nearing Frame both in reference to the amateur as well as the professional propagation of rhododendrons. Particular emphasis will be given to the cyclic change in plants as related to the dormancy state and how the Nearing Frame can eliminate many frustrations connected to propagation, especially the large-leaf varieties.
In one sense, the Nearing Frame "hides" the influence of dormancy. Dormancy plays a major role in determining how and when plants will root. This factor becomes more important with difficult to root clones. The amateur without a greenhouse faces a real dilemma. Even though the easy to root cultivars can be rooted under lights, how does one arrange for after chilling to satisfy the dormancy period so that bud break will occur?
Historically, there have been many accomplished rhododendron specialists who have grappled with this inconsistency and have either knowingly or unknowingly migrated to the Nearing Frame to let nature work the dormancy period and avoid frequent bad results.
Following is a list of advantages of the Nearing Frame:
1.  Easy maintenance.
2.  Low cost.
3.  Better results with the difficult to root large-leaf varieties.
4.  Better organization and use of time.
The disadvantage is prolonged rooting and removal time. This is easily compensated for when once in use.

Author's Modification
The first modification is the container for the cuttings. For the rooting bin, I have substituted a plastic container which has significant advantages (see Figures 1, 2). The container, which goes under the name Wrap'n Craft Underbed Box, is manufactured by the Rubber Maid Corporation, Wooster, Ohio. The measurements are 16 x 36 x 5 inches (40 x 90 x 12.5 cm). It was purchased at Lowe's Home Improvement Warehouse. Approximately 50 to 60 large-leaf rhododendron cuttings can be placed in each container. For the roof, the following modification has been made: partially opaque plastic panels are attached to a frame which is hinged to an underlying frame. This allows for opening and closing depending upon the season. Since the panels allow for light transmission (20-30%) the frame can be placed in shaded areas for ultimate convenience (see Figures 3, 4). The plastic paneling can be purchased at the same warehouse center. The structure can be easily assembled and disassembled. If the frame is placed in a sunny location, cloth can be draped over the top and sides. For anchorage of the lid when open, a metal post is driven into the ground beside the frame. There may be other innovative designs for the roof to admit indirect light. Peg board or other louvered baffling are examples.

The lower frame is made of two-by-sixes with the measurements being 23 x 42 inches (57.5 x 105 cm). Two-by-fours are used for the upper matching frame which extends forward an additional 5 inches (12.5 cm) to allow for rain protection when open. The upper measurements are 28 x 42 inches (70 x 105 cm).

A Second Modification
For the ultimate in convenience and portability, I use 10-inch (25 cm) white plastic hanging baskets. The hangars are removed, and a 3-mil plastic covering over each top is secured with a string attached to a rubber band (see Figure 5). Each basket holds eight large-leaf rhododendron cuttings after the leaves are trimmed. Cuttings can be placed either during the early summer or early fall. The white baskets afford maximum light intensity. The medium is equal parts of Canadian peat moss and perlite.

As freezing weather approaches, the pots are placed in an 8-inch (20 cm) mulch of grass clippings and leaves. An individual well is made for each pot with only the very top remaining above the mulch. A fiberglass sheet is then placed over the containers and the mulch is pulled up to the edge of the plastic panel for complete insulation (see Figure 6). The use of a shaded cold frame or a cool greenhouse with extra internal shading might be considered as alternatives.
The pots should be placed in highly shaded areas. Pines and yews are very good with shaded lanes being ideal. I do not believe that a small amount of sunlight offers a significant hindrance.
As with the original Nearing Frame, the moisture level should be checked periodically during the winter. This is easily accomplished by lifting the pots for their weight content. Watering should not be done when frozen. Rooting occurs the following summer or fall depending upon when the cuttings were inserted. Because of the portability, the pots can be placed under indoor lighting at any time, thereby hastening the rooting time. This latter exercise seems very promising, especially after keeping in a cold state outdoors for a period of months.
I have been greatly encouraged by the simplicity and results. It offers a great deal of flexibility with the use of one pot or many. Finally, I believe there will always be a need for a rooted cutting method of propagation because of the inherent variability that occurs with tissue culture propagation

Preparation of Cuttings
CONTAINER PREPARATION FOR THE PLASTIC NEARING FRAME MODIFICATION:
1.  For the medium, I prefer to use equal parts of screened Canadian peat moss and perlite which is pre-wetted. A superlative medium is equal parts of milled sphagnum moss and perlite; however, the cost probably limits the use to special needs.
2.  The depth of the medium is approximately 3 inches (7.5 cm) which allows for 1-2 inches (2.5-5 cm) of air space.
3.  The leaves are reduced by one half.
4.  The stems are reduced to 1-inch (2.5 cm) in length with wounding on both sides distally.
5.  Hormones: either powder or liquid forms can be used, but the latter might be preferable.
6.  For convenience, the container can be placed on a workbench for placement of the cuttings.
7.  Rooting cannot be expected until the end of the following summer.
8.  Large-leaf cuttings are best taken in early fall. Some may do better in mid summer, while others late fall.

SITE PREPARATION:
1.  The container is buried in the ground approximately 3 inches (7.5 cm).
2.  A 3-mil plastic liner is placed beneath the container for additional winter insulation.
3.  As freezing weather approaches, Styrofoam panels are laid over the container for added protection. The cuttings can be kept in complete darkness during the dormancy state without harm.
4.  The frame should face true north; however I do not believe the control of light is as critical as once thought.

MAINTENANCE:
1.  Watering time is determined by lifting the container to determine the weight. Using a fine nozzle is ideal. A soft drink bottle with four or five small holes in the cap makes an ideal device. Watering is needed on a regular basis, but very little is necessary during winter. Cuttings use water continuously to support physiological processes. Quite often hand misting is enough, which can also be done on the underside of the lid for added humidity.
2.  Do not water when the medium is frozen.
3.  The container can be kept in a convenient shaded area until freezing weather approaches.
4.  Root formation can be observed from the outside if the stems are placed near the container wall.

ALTERNATIVE OPTION:
The container can be over-wintered in a shaded area, but it should be buried for the insulation effect. A shaded area would also have to be provided for the following spring and summer (see Figure 7). Storing in an unheated garage might also be another possibility.

Summary
The purpose of the Nearing Frame is to provide a structure which allows dormancy to pass naturally under ideal, highly controlled conditions. The positive results have proven better, especially with the large-leaf difficult clones. Great frustration can be avoided if the dormancy factor is allowed to be satisfied. Updated versions have been presented which have simplified and made the Nearing Frame more convenient to use. The low maintenance and low cost are other advantages. I believe it is important to use this method so that many propagators, both amateur and professional, can perpetuate the wonderful genetic material that has become our legacy over the last 120 years.

Dr. Konrad, a member of the Great Lakes Chapter, is a frequent contributor to the Journal. His most recent article, "Some Thoughts on Vegetative Propagation As Related to Dormancy' appeared in the summer 1998 issue.