Horticulture Fact Sheet
H-93-014

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Implementing a Quality Control Program in Nursery and Greenhouse Operations

Mel Garber, Extension Horticulturist; John Ruter, Nursery Crops Research

The value and sales of plants produced by the nursery industry is affected by the quality of the finished product. The quality of finished plants (nursery crops, floriculture crops, vegetables) is influenced by the quality of the starter plants. In turn, the value and demand for plugs (starter plants) will be influenced by their quality. Thus, the entire nursery industry has a vested interest in producing quality plants on a consistent basis.

The production of consistent quality plants requires that nurserymen develop a system to control key production variables -- a Quality Control Program. There are many variables in the production of ornamental plants, and unless these are identified and managed, the quality of plants will probably be erratic. The production time and the percentage of a crop that is marketable will also vary.

The implementation of a quality control program in various industries is the subject of many texts. In this fact sheet, we identify several key steps to initiate a quality control program for plant nurseries. We also discuss how these procedures can prevent production problems, based on actual experience with Georgia nurseries.

Step 1: Develop a Simple Flow Chart for Your Production Process. In this process, you identify the major production steps. These will vary with the type of nursery you operate. The major steps for a container woody ornamental nursery would include cutting production, liners, #1 containers and #3 containers. Additional detail would include the type of production facility, e.g. shadeliners, sun-liners, rain-bird, #3 container, drip #3 container, etc. A greenhouse bedding plant operation might include purchase of plugs, flats, 4" pots and 6" pots. The more detailed the flow chart, the more detailed can be the quality control procedures. A vegetable transplant operation might consist of one product line/size. Most vegetable operations use either overhead irrigation or the float system.

Step 2: Identify the Inputs Necessary for Each Stage of Production. These generally include fertilizer (liquid feed, granular; if granular, regular release or control release), growing medium, containers, starter plant material (seed, cuttings, plugs, bare-root liners, etc.), water (well, pond), plant growth regulators, pesticides, herbicides, etc.

Step 3: Develop Specifications/Requirements for Each Input. The specifications for each input should be two or three features critical to production of a quality plant (See Table 1 for examples). The specifications should be quantitative (something you can measure and verify). This process requires the producer to identify inputs and specifications for production of quality plants.

Step 4: Develop Procedures to Verify that Each Input Meets Specification Standards. The procedures developed will be critical to success of your quality control programs. Ideally, the procedure to verify would be real-time, e.g. immediate recognition or verification that the input meets specifications. Also, the information collected should be quantitative, so as to assess variation that might occur. The verification procedures should be incorporated into the routine production procedures with an established frequency of measurement. The frequency of measurement can vary from every time the input is applied, to daily, to once a crop cycle, etc.

Step 5: Operational Procedures. The above information can be incorporated into a single chart for ease of use (See Table 1). In Table 1, the inputs, specification for each input, and verification procedures are identified for one product and stage of production. You may purchase individual bags of a peat-lite mix of pH 6.2 with no fertilizer incorporated. A procedure that calls for the receiver to check the invoice or bag label for content would not be sufficient. It only confirms that the vendor has labeled the product correctly. An appropriate procedure might call for periodic measurement of soluble salts and pH of the media prior to use in production. The same varification procedure could apply to media mixed on your nursery that may have fertilizer incorporated. You need to verify that the media was prepared properly prior to use rather than dealing with subsequent abnormal plant growth. If you use a liquid-feed system for a greenhouse or nursery operation, the concentration of the fertilizer solution should be verified prior to use. The concentration of total soluble salts or of specific salts such as nitrogen is the key factor to monitor. In nursery situations, recommendations are based on concentration and the amount of the solution applied varies with the size of the container, generally applied to run-off or to replace the media solution. In a float system, the concentration is set when the initial solution is formulated. Total soluble salts is usually the quickest, easiest and least expensive measure of the fertility level. Total soluble salts should be checked for each batch of fertilizer mixed. The salt reading from the salt meter can then be equated to the concentration of the fertilizer being used. The soluble salt readings and nitrogen concentrations for two common liquid fertilizers are presented in Table 2.

Nursery visits in Georgia have revealed numerous cultural problems that could be prevented by implementing the above procedures. Examples include: (1) nurserymen felt that one batch of plants were diseased because they were dying-back while the other group was normal (the two batches were from different sources). We found no evidence of disease and by checking the soluble salts of the growing media, determined that the soluble salts were about 1Ox the recommended level. The grower then realized that one batch of media (which he mixed) had osmocote incorporated twice. He could have saved the crop by checking the media soluble salt levels prior to potting! (2) a greenhouse operator had been fertilizing with liquid 20-10-20 for about one-half day at the time of the nursery visit. We measured the soluble salt reading for the solution coming out the end of the hose and, using Table 2, found that the level of nitrogen was about 25 ppm versus the 150 ppm thought to be applied. The injector was working properly but the stock solution was too dilute. Requiring the fertigator to measure soluble salts prior to applying "fertilizer" and, recording the data, would avoid such a problem. This also provides documentation of variations that might occur in the fertilizer concentration. Implementation of a quality control program requires up-front management time but generally is inexpensive, can save entire crops and, ensures better and more consistent quality plants. Other benefits include fewer burned plants from too much fertilizer, decreased scrappage due to chlorotic or low vigor plants, faster (or at least more controlled growth rates), and, perhaps most important, satisfied customers.

The University of Georgia and Ft. Valley State College, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.

An Equal Opportunity Employer/Affirmative Action Organization Committed to a Diverse Work Force

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.

Gale A. Buchanan, Dean and Director