Greenhouses
There are many factors to consider in determining the amount of greenhouse space you will need. Amount of investment capital, training, the type of business, environmental requirements, market, labour requirements and personal preferences must all be evaluated. You should also be aware of factors which are important in choosing a good building site, such as drainage, accessibility, available utilities and amount of sun exposure.
There are companies such as Crop King who sell greenhouse packages which contain everything needed for turnkey operation. Greenhouse tomatoes with indeterminate growth habits are best managed in houses with high roofs. The structural design of a greenhouse must provide protection from wind, rain, heat and cold. The structural supports must be of minimal size to permit maximum light transmission to the crop while still supporting the structure itself, heating and ventilation units and the weight of the crop which is trained to grow up a support system carried by the greenhouse frame.
There are a variety of types of greenhouse covers. Glass is still a common glazing material. Large panes reduce the shading of the crop from the support frame. While shading may seem minimal in traditional greenhouses, it is estimated that every 1% decrease in light will result in a 1% decrease in yield.
Despite the common use of glass as a covering for greenhouses in Northwest Europe, glass remains inflexible, heavy, and expensive. Consequently, the hectarage of glasshouses on a world basis has remained static, (approximately 30,000 ha.) during the last 25 years. In contrast, the quantity of plastic used for greenhouses is increasing rapidly. Since polyethylene sheet film was first developed in England in 1938, it has been used widely in greenhouses because it is easy to work with and inexpensive. Worldwide, there are nearly 300,000 ha. of plastic greenhouses for growing high value horticultural crops.
Several other plastics have also been used for greenhouse glazings. Polyvinylchloride (PVC) has a very high emissivity for long wave radiation (similar to glass), which creates slightly higher air temperatures in the greenhouse during the night. The Japanese consider this improvement in thermal environment a benefit that outweighs the price advantage offered by the less expensive polyethylene (PE). The disadvantage of PVC is its narrow width as compared to PE, which may be manufactured in widths of up to15 meters. The narrow PVC sheets can be heat-welded together to form a large sheet, but this adds to the cost of the glazing material.
The large sheets of PE can be applied as an air-inflated "blanket" over a greenhouse: two sheets of PE are separated by air pressure maintained by a small continuously running fan. This arrangement provides approximately 30-40% heat savings during winter. The double-layer, air-inflated roof has also proven valuable in regions with high winds or typhoons. It offers stability during these conditions, saving the greenhouse and the crop during times when structures covered only with one layer of plastic are often lost and the crops damaged or destroyed. PVC film is not suitable for air-inflated roofs because the air pressure stretches the film and reduces its structural strength. Because PVC film is not photodegradable, as is PE, environmental concerns about disposal may diminish the use of PVC in Japan in favor of PE, which is the predominant cover for greenhouses worldwide
New materials such as double-skinned panels made of polycarbonate and acrylic are becoming increasingly popular. Unfortunately, their technical merit is offset by high costs, making them affordable only in the industrial nations of the world rather than in developing agricultural communities.
The ideal greenhouse "selective film" should do the following:
Transmit the visible light portion of the solar radiation spectrum, the only portion utilized by plants for photosynthesis.
Absorb the small amount of ultraviolet radiation in the spectrum and cause some of it to fluoresce into visible light, useful to plants.
Reflect or absorb infrared radiation , which plants cannot use and which cause greenhouse interiors to overheat.
Minimize costs, and have at least a 10 to 20 year useable life.
Starting a Commercial Greenhouse Business
Introduction
Success in the greenhouse business requires a well-defined market, a good location, significant capital, a well-planned production system, people skills and experience in dealing with the "mechanical" necessities of the business.
Identify Your Market
When you first look at the greenhouse industry, you will see that it is quite large, very diverse and extremely competitive at all levels of production and marketing. One of the most asked questions is "What can I grow to make money on?".
It is critical to take the time to develop your business plan. The business plan summarises your business objectives and how you will attain them
Greenhouse vegetables are either tomatoes, cucumbers, sweet peppers and/or lettuce. The production is geared towards the packers/wholesale market for distribution through the chain stores and fruit/vegetable markets. Greenhouse flowers include cut flowers, potted plants and bedding plants. The production is either geared towards the wholesale market (chains, garden centres, florists) or in the case of bedding plants may be direct to the consumer in what is called a retail grower situation.
Location
There are many factors to consider when selecting a site for your greenhouse business. Just because you already have a piece of land does not necessarily mean it will be a good location!
Natural Gas - this is the most efficient of the fuel sources for heating your greenhouses. ie. the cost per BTU is less than oil or propane and since heating may represent from 15-35% of your total operating cost is significant. You will also find less equipment maintenance problems with natural gas. Natural gas should be available at your location and normally you would pay for the cost of making the connection from the outside wall of the boiler room to the boilers/heaters.
Water - a good supply of high quality water is critical to the success of the business. Have the water analyzed for a full range of criteria from a recognised laboratory. Basically the Total Salts, pH and bicarbonate levels along with some of the specific nutrient ions will guide us. New entrepreneurs in the greenhouse business should also be aware of the trend towards growing plants in an "enclosed" system where the irrigation water is captured and re-used.
Hydro - 3 phase power is much more efficient than single phase both in the initial purchase of equipment (motors) and their operation.
An on-site generator will also be an "essential" piece of capital equipment to handle power interruptions of your hydro supply.
Soil - the type and drainage characteristics may be particularly important if you plan on growing the crop directly in the ground. Cut flower crops such as chrysanthemums and snapdragons require lighter, well-drained soils especially for winter production.
Suppliers - to your greenhouse business are important and in particular their closeness/accessibility when equipment fails or supplies are needed in a hurry. It is difficult to have a successful greenhouse business in a "remote" area. As a production facility, the need for a constant supply of "inputs" is on-going.
Customers - and the importance of being close to them whether you are in the wholesale or retail part of the business is important. For retail growers where the crop is being sold directly to the public a major cost of doing business is actually getting the customer to your greenhouses. The old adage, the 3 major factors to consider when setting up a retail greenhouse are "Location, Location and Location".
Capital
The greenhouse business is very capital intensive with the basic structure erected ranging in price from £8 - £12 per sq. ft. depending on such major options as covering materials, ventillation systems, etc. Next we need to provide heating (both the source and distribution), irrigation (source and distribution),electric service (main connection and interior work),nutrient injection system for the irrigation water complete with pH and E.C. controllers, environmental computer to "run" the heating/cooling requirements with the option of adding humidity, CO2 and irrigation control. Now we need to build some type of support buildings for storage/shipping, staff room, office, etc. Add in some pesticide application equipment, concrete walkways, benching or a crop support system, high pressure lighting for the starting and/or finishing areas AND before long you have a total investment of £25 - £35 per sq. ft.
One of the realities of the greenhouse business is that the initial capital investment must make a return from operations because the re-sale value is only a fraction of the initial investment.
Production Systems/Economics
Vegetables
Greenhouse vegetables are usually grown in an artificial media such as rockwool or NFT(nutrient film technique) because there is better control of the total growing conditions compared to growing in the soil.
A one acre size facility may be the starting point needed in order to have any economies for the required equipment (boilers, fertilizer, generator, service/packing building, etc).
There has not been accurate cost of production studies done in the greenhouse vegetable business and we know there is a wide variation of income based on crop yields, market prices and timing of the production. An estimate for gross revenue is £12 per sq. ft. of greenhouse area for a wholesale grower. Heat cost will be close to £1 per sq. ft. for the whole year.
Tomatoes are normally planted at a population of 10,000 plants per acre. The main variety is Trust (an excellent red tomato) and a yield in the range of 35-45 lbs. per plant can be expected under excellent conditions. Average price has ranged in the £0.62 - £0.90 per pound.
Seedless Cucumbers are normally planted at a population of 5,800 plants per acre. There are a wide range of varieties, each with some special characteristics. The expected yield is in the range of 85-110 cucs per plant with an average price of £0.60 - £0.75 each.
Sweet Peppers are normally planted at a population of 10,000 plants per acre. There are a wide range of varieties in the different colours of red, green, yellow and orange. An expected yield is 18-20 lbs per plant with an average price of £1.80 - £1.90 per pound.
Note: The expected yields are from a well managed modern production system and can be drastically lower if any factors are limiting.
Flowers
Cut flowers-Some of the more common cut flowers such as roses and chrysanthemums are being cautiously planted now due to the ease of their importation from southern climates (equator countries). This import pressure has also served to lower average prices.
More difficult to import cut flowers such as gerbera, snapdragon, lily and lisianthus are being planted more often. The bulk of the cut flowers are sold through the traditional retail flower shops and as such have not enjoyed big increases in sales. The "Cash and Carry" type of marketing by the large chain stores and independent fruit/vegetable markets is moving an increasing volume of cut flowers.
Yields and therefore revenues will fluctuate greatly but expected gross returns per sq. ft. will be in the £8 - £12 range.
Potted flowers - can be classified as being on a weekly schedule such as chrysanthemums, violets, begonias, etc. or holidays such as poinsettia, Easter lily and hydrangea. For this type of crop, the cost of production can include the pot, media, plant material(cuttings, bulbs, etc.), growing time on the bench (usually calculated at £0.15 per sq. ft. per week) and shipping material (pot cover, box). Revenues are in the £12 per sq. ft. area but can be significantly higher depending on pot sizes and number of crops per year (ie. turns on the bench).
The major market for potted plants is the chain store who has taken over to a large extent from the traditional retail florist. Low mark ups, little/no service and strong competition are what has kept retail prices stagnant for potted crops.
Bedding Plants - The Spring production of bedding plants is quite often the starting point for people getting into the greenhouse business probably because of the strong demand for plant material and the relative ease of starting. Many will start with a small hoop-shaped quonset greenhouse, unit heater, ventilation fan and some snow fence benching.
Growers can purchase flats already filled with media, plugs (small, singulated plants) from specialist propagators or buy already transplanted flats for their greenhouse. In short, you can be in business very quickly.
The bedding plant season usually will yield 1.5 turns for the floor space and about 25% additional with overhead hanging baskets. Gross returns are in the £8 per sq. ft. area. Average wholesale price per flat is £8 with direct costs being around £5.
Bedding plants are either sold direct (by retail growers) or to the chain store/garden centres.