UNIVERSITY OF KENTUCKY --- COLLEGE OF AGRICULTURE --- DEPARTMENT OF HORTICULTURE

Tobacco Greenhouses

Crops for the Summer, Fall and Winter

Many tobacco farmers in Kentucky have interest in the use of their tobacco greenhouse during the summer, fall or winter. It is correct to assume that because the greenhouse was a large investment, it would be wise to make use of this facility through many months of the year.

A greenhouse can be used to grow many different crops. Typical Kentucky commercial greenhouses may grow 500 or more different kinds of plants in a single year. The challenge for tobacco farmers is to find both a market and plant production cycle that can be integrated with the planned tobacco production schedule.

The Greenhouse Situation

The greenhouse industry in Kentucky and the rest of the U.S. is quite large and over the last 30 years, greenhouse technology, crops, and markets have changed dramatically. The typical greenhouse has 3 primary crops: bedding plants in the late winter and spring, garden mums in the summer, and poinsettias in the fall. Spring bedding plants give greenhouse businesses their major cash flow. Profits are good and the market continues to expand at nearly 10 percent each year. The market for garden mums and poinsettias is smaller and highly competitive so most greenhouses break even on these crops. These crops allow greenhouse operators to pay their full-time employees for the calendar year.

In general, only a few greenhouses in the Midwest have production peaks in winter. Natural light levels are quite low and heating costs are quite high. In most cases, poor plant growth (because of low light) and high heating costs prevent economical greenhouse crop production in the middle of winter. The spring greenhouse with high light levels and moderate temperatures offer the best greenhouse conditions and that is why the bedding plant industry has such good economic performance.

Possible Ornamental Crops

Any plant can be grown in a greenhouse. Many simple and complicated techniques have been developed over the last 100 years for plant production in a greenhouse. The questions, though, are "Is there a market to sell a specific plant?" and "Can I grow a specific plant economically?" These questions have to be answered on a plant by plant basis, grower by grower basis and market by market basis. Although there is a large greenhouse industry in the U.S., the businesses are based primarily on marketing rather than production.

	Bedding plants: Bedding plants are the best greenhouse crop in the U.S. The highest profits and most industry growth is related to the hundreds of different kinds of plants grown for landscape, porch and patio use. If a farmer has tobacco in his or her spring greenhouse, then bedding plants are not a choice.
	Garden mums: Garden mums have become the primary summer crop for commercial greenhouse operators. In the last 20 years, mum production has increased from 50,000 plants to nearly two million plants in Kentucky. The market seems saturated for high priced mums but low priced mums, with a minimal profit margin, continue to increase. Garden mums are quite easy for a farmer to grow but the market is questionable. These plants would not use a tobacco greenhouse, these plants should be grown outdoors with a trickle irrigation system.
	Poinsettias: Poinsettias can be grown in a tobacco greenhouse during late summer and fall. These plants are the #1 potted flowering plant in the U.S. so the market is relatively large. Greenhouse operators have become quite efficient in poinsettia production so while the market is large, profits remain small. Poinsettias are moderately easy to grow, but might compete with tobacco harvest, housing, and stripping for farm labor.
	Landscape shrubs in containers: The market for landscape shrubs and perennials continues to expand each year. The production of these plants fits the production schedule of tobacco transplants quite well, if a grower has an appropriate watering system. A farmer can purchase high quality liners (cuttings or plugs) for these plants in late May, early June or in July (depending on the plant) and transplant them into 1 gallon nursery containers. The plants are grown all summer with fertigation from drip systems or subirrigation from the Bottom-Up^TM system or the Controlled Water Table system developed at the University of Kentucky. When the temperatures are cold enough, generally mid November, the plants are moved into the empty tobacco greenhouse (approximately 3 plants per square foot of greenhouse space) to be protected from cold temperatures during the winter. The greenhouse temperature should be maintained at 30⁰ to 35⁰ F. during the winter. In late February or early March when tobacco will be sown, these plants can moved outside and protected, when necessary with tobacco canvas or polyethylene in the structures that will be used for outdoor tobacco float beds in a few weeks. These plants can be sold to garden centers in mid to late March, at prices of $2.00 to $5.00 per plant, for the usual spring planting season.
	Cut flowers: The market for cut flowers is very large in the U.S. Almost all cut flowers are imported from South America but there is a niche for uncommon cut flowers grown in Kentucky. A tobacco farmer would need to learn a great deal about the cut flower market and cut flower production before starting such an enterprise.

Possible Greenhouse Vegetable and Fruit Crops

Greenhouse tomatoes: Many tobacco farmers think of greenhouse tomatoes first when they consider other crops to grow in their transplant greenhouse. Most don't realize that greenhouse tomato production has been insignificant in the U.S. for nearly 20 years. The greenhouse tomato or hydroponic tomato market is increasing dramatically now. The U.S. consumer will now pay an increased priced for a red, ripe tomato so investors are building greenhouse tomato businesses in a number of U.S. locations. It would be possible for small greenhouse tomato operations in Kentucky, on tobacco farms, to sell greenhouse tomatoes in this expanding market. Greenhouse tomatoes are the most complicated greenhouse crop to grow. They require the most management, most labor and most light of any crop. So a tobacco farmer must be committed to this crop, over all other farm activities, in order to be successful. Two years of work at UK with tomatoes in a fall greenhouse demonstrate that yields are decreased in the fall due to low light. Most farmers who have tried fall greenhouse tomatoes have felt that the effort was not worth the returns. On the other hand, spring greenhouse tomatoes should have high yields, 20 pounds per plant, that easily justify the effort. The best suggestion for a tobacco farmer who wishes to grow greenhouse tomatoes would be to use the greenhouse for tomatoes in the spring and grow tobacco transplants, a late crop, on outdoor beds.
Greenhouse cucumbers and peppers: These crops require the same conditions as greenhouse tomatoes but have a much smaller market.
Strawberry: The market for strawberries is very strong in the fall and winter because production can be limited in Florida and California. Although strawberry production systems have been designed for greenhouses, these systems are expensive and the low light levels in fall and winter greatly reduce yields. Additionally, little knowledge exists regarding the best cultivars, the best size plant to grow, the best source of plants, and how to manage potential insect problems.
Raspberries: Certain raspberry cultivars are suitable for greenhouse production. These varieties produce flowers and fruit on the first year's wood and are called "primo-cane" varieties. Plants are grown in 2-3 gallon containers and irrigated with trickle irrigation. Additionally, plants need to be supported so workers can move through the rows. Plants are stored dormant for 6-8 weeks in winter to get sufficient chilling, then can be brought to moderate (60 degrees) temperatures in the greenhouse. New canes will develop and produce flowers and fruit. This may be repeated 3-5 times during the summer and fall, depending on greenhouse temperatures. Workers in Canada and New York, who developed this procedure, feel raspberries offer better opportunities than strawberries.
Lettuce: Leaf and bibb lettuces are well adapted to the float system and tobacco greenhouses. There are 20 or more specialty lettuces that have an increasing market in supermarkets and restaurants. Although the market is increasing, it is still not large. Lettuce can be grown in outdoor beds during late summer and fall, then moved into cool tobacco greenhouses. The plants can be grown in 'float' trays in the same way tobacco transplants are grown. The biggest problem for lettuce is insect control. There are few insecticides cleared for this crop in the greenhouse. The use of insect screens would be very important to commercial production.
Culinary herbs: Herbs are a specialized crop for a tobacco greenhouse. The market is relatively small but good profits can be earned by those farmers who aggressively attack this enterprise. Most herbs cannot be grown easily with the float system, overhead watering will be required. Insect control will be a major problem and the use of insect screens would be important.
Greens: Greens, such as mustard, kale, collards, etc., can be grown successfully just like lettuce in a tobacco greenhouse. These plants prefer cool conditions and can be grown at temperatures just above freezing. Yields will be good during the fall but yields will drop during the low light and cool temperatures of winter. Insect control may be a major problem.

Other Considerations

The decision to build a greenhouse for tobacco transplants should not be influenced by the possibility of using that greenhouse for other crops.
If you plan to grow small amounts of tobacco transplants only for your farm, consider building simple small greenhouses (like walk-in outdoor beds) rather than a large greenhouse. If you plan to build large commercial greenhouses, focus your enterprise on the production of large numbers of tobacco transplants and plugs that can be sold to others. Spread the cost of a large greenhouse over many tobacco crops, rather than assuming that you will find other crops to help pay for the greenhouse.
If other crops are very important to your plans for a greenhouse, consider a typical commercial greenhouse rather than a greenhouse built primarily for tobacco transplants. Side curtains require a great deal of management for ventilation and can be heat wasteful during the winter heating season. Fan ventilation will work much better for most other crops and cropping systems.
Development continues for capillary mat subirrigation systems for plant irrigation in tobacco greenhouses and outdoor beds. This system developed by Jack Buxton and Bob Anderson in the Horticulture Department at the University of Kentucky will allow the production of many different crops on benches or on the float beds you currently have on your farm. Ask your county extension agent for more information.
The development of produce marketing co-ops and farmer's markets across the state offer significant opportunities to sell fresh produce from your farm. Regular communication with the people involved will help you decide what crops, especially lettuce and greens, that you could grow in the fall and early winter to sell through these markets.

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