The University of Georgia college of Agricultural & Environmental Sciences
Cooperative Extension Service

Topics for Consideration before Purchasing a Greenhouse for Growing Tobacco Transplants

William Givan and J. Michael Moore, The University of Georgia

When Considering a Greenhouse
Selecting a Greenhouse
Comparison with Conventional Plant Bed
Conclusions

The cost of plants represents less than 4% of the costs of growing tobacco. But healthy, disease-free plants are essential for a successful crop.

Growers have traditionally grown transplants in beds, and it is a common practice to purchase plants from commercial growers.

In recent years, the production of plants in greenhouses on farms has been introduced. Currently an estimated 15-20% of the plants used in Georgia are produced in greenhouses. Some neighboring states report higher percentages.

When Considering a Greenhouse

The primary advantages of using greenhouse-grown plants are:

• Lower labor costs at transplanting;
• More uniform Plant Size;
• Faster growth after transplanting; and
• Uniform plant growth resulting in savings on sucker and insect control.

Disadvantages associated with the systems are:

• Increased levels of management required, and
• The greenhouse represents a substantial initial investment.

Selecting a Greenhouse

The most common type greenhouse in use is a direct seeded float system. This system uses trays with potting soil in which the plants are grown. These trays are placed in a waterbed over a plastic cover on the ground which allows the transplants to receive water and nutrients through the waterbed. However, other type systems are available, such as one with an overhead water system.

Cell numbers per tray vary from 200 to 392. But it should be noted that trays with a larger number of cells have a much higher density of plants, making practices for controlling diseases and insects more precise. Although more plants can be produced in smaller size cell trays, the percent usability of plants often declines with smaller cells.

Note: Cost data for this article were obtained from "The Cost of Greenhouse Transplant Production," by Tara Lychak and Blake Brown, North Carolina State University, released September 20, 1993.

Two applications of fungicides and one application of insecticide are included in this cost estimate, but this can vary from farm to farm. Annual replacement of trays was calculated at 5% to account for those trays that become cracked and damaged and are not usable the following year. Also, the black plastic water liner (included in the investment cost) has also been placed in operating costs as it must be replaced annually.

It is important that extreme temperature fluctuations which can cause damage to the plants be avoided. For this reason, a generator is included in the investment to function as a backup in the event of power loss. Annual repairs of the greenhouse and equipment are included in annual costs, and are estimated to be 2% of each of the investment and equipment.

Total annual cash operating costs for this greenhouse (30' x 245') are estimated to be $5868.68.

Labor Costs

Daily managerial duties are essential for a successful greenhouse operation. General management can require 1-1/2 hours daily for the approximately 65 days the transplants are in the greenhouse. This involves checking all details and making sure conditions are adequate for healthy plants. Seeding labor time is approximately 100 hours to seed the 2516 trays of 288 cells each. For this budget, an 80% yield was used, which would provide 579,686 plants. Based on 6,000 plants per acre, this would provide plants for 96.6 acres of tobacco. But some farmers are achieving higher yields of plants (85-90%), which provides even more usable plants. Table 3 below shows how plant numbers and cost of plants will vary as the efficiency changes.

Looking at specific jobs, clipping a greenhouse of this size takes about 1 1/2 hours, and on the average, will probably be done five times. Clipping helps increase uniformity, improve quality and reduce premature flowering. But caution should be taken to bag the clippings and to sanitize the mower to prevent the introduction and spread of tobacco mosaic virus.

A major advantage of a greenhouse production system is that plant pulling time is greatly reduced. The plants can be taken to the field still in the trays, then pulled, and transferred to the field. This is in contrast to an estimated 16 man hours required to pull the same quantity of transplants from a bed. Also, less labor is required for transplanting greenhouse grown plants. A carousel transplanter can be used which requires only one person per row, compared to two people per row with a traditional transplanter. A 4-row carousel transplanter costs about $12,000, approximately twice that of a conventional transplanter. Operating cost estimates indicate total operating costs per acre will be less for the carousel transplanter because less labor is required.

Ownership Costs

Ownership costs consist of depreciation, taxes and insurance. Depreciation is the prorating of the original cost of an asset over its use life, but is often overlooked, as it is a non-cash cost.

Items in the greenhouse package plus those purchased separately for construction are depreciated over a 15-year life. The structure will last longer, but it will likely become obsolete before it wears out. The plastic cover is expected to last for three years, so it is placed in a separate depreciation category.

And while the water bed liner is a part of the initial investment, its annual replacement in included in operating inputs. Equipment associated with the greenhouse is depreciated over a 10-year period.

Taxes and insurance are estimated by multiplying the current tax rate per $100 of investment. The total ownership cost of the structure and equipment is estimated to be $3470.32.

Comparison with Conventional Plantbed Production

A traditional plantbed budget (Table 4) is included for a cost comparison. The major differences are:

• Ownership and capital costs are higher for the greenhouse due to the higher cost of investment.
• Labor costs are higher for the plantbed.
• Overall, total production costs at 80 percent stand are $2645.85 higher for the greenhouse -- a difference of $27.00 per acre more than a plantbed.
• This cost difference can be reduced to $14.00 per acre by the use of a carousel planter.
• If a 90% stand of plants can be obtained, costs of the two systems are near equal.

Conclusions

Use of greenhouses to grow tobacco plants is on the rise and results in a significant labor saving. The elimination of many of the problems associated with obtaining and managing labor at transplanting time appears to be causing many growers to adopt greenhouse transplant production. This information is intended to assist growers evaluate greenhouse plant production by using the budgets and considering the merits of the system. But all factors need to be considered: (1) Investment outlays, (2) Operating costs, (3) Labor savings, and the input most difficult to measure... (4) Management.

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

Issued in furtherance of Cooperative Extension work, Acts of May 18 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