One of the frequently asked questions is “how much does it cost to produce strawberry hydroponically in greenhouses”. Our costs estimate of a typical off-season production cycle (10 months of plant growing for 8 months of fruit harvest) suggests that operational costs for greenhouse strawberry production located in Midwest region are likely $3-$4 per sq ft of greenhouse (10 months) at 10 plants/m2 density (growing area). However, values can be very different for different climate conditions, growing systems, transplants, IPM, other materials and utility cost structures. Therefore, we list the key cost information below to assist in your own analyses for your specific scenarios.
Assumptions made in this analysis.
A hypothetical greenhouse with 10,000 sq foot of floor area was considered when area-based cost estimation was needed. 7,250 plants can be grown in this space using a standard fixed hanging gutter system (10 plants/m2 in growing area). Available water source is assumed as municipal water due to its semi-urban location.
Key information used for estimating costs.
Labor costs. Dutch-style greenhouse operations for tomato anecdotally require 3 workers per acre of greenhouse and an additional worker for packing. We consider that strawberry crop management is slightly less labor intensive than high-wire tomato crop management (2 workers per acre?). While harvesting strawberry may take longer labor hours than tomato, time consuming pruning, clipping, and leaning/lowering are either less or not needed for strawberry. However, this needs to be verified for commercial operations. Wages can be $12-$15 per hour plus 25% of fringe costs, for example.
Heating costs. Heating fuel costs are estimated using software developed by USDA (Virtual Grower). This software is based on greenhouse energy balance and can estimate reasonably accurate heating fuel use and costs for selected designs of greenhouse under selected conditions of inside/outside the greenhouse. When the greenhouse day/night temperatures were 65/50F in central Ohio and the natural gas price is $0.79 per therm (usage cost), the software will estimate 1,199 therms necessary to achieve the temperature set points of a 10,000 sq ft glass greenhouse with relatively good energy-saving properties. By considering an additional monthly service charge for natural gas of $120/month, the total heating costs estimated were $0.57 per sq ft over 10 months of production.
Electricity costs (not including lighting). This cost is for electric power usage for all equipment and machinery used in the greenhouse. A hydroponic greenhouse budget reported by OSU Extension estimates $4,000 of electricity costs per year for a 12,288 sqft greenhouse. Based on this number, the electricity cost over 10 months is estimated as $0.27 per sq ft. For strawberry, additional power may be required for postharvest refrigeration.
Supplemental lighting electricity costs. This cost varies depending on the type of lamps, lamp efficiency/efficacy and target light intensity. At a relatively good efficacy of 2.6 mmol/J and 100% utilization factor, lighting cost is approximately $0.01 per one mole of photosynthetically active radiation, when the electricity rate is $0.09/kWh. When supplemental lighting is operated to achieve a minimum DLI of 12 mol/m2/d in a greenhouse with 50% sunlight transmission, located in central Ohio, the lighting electricity costs over 10 months of production were estimated as $0.54 per sq ft.
Water/fertilization costs. A very rough estimate of water use based on greenhouses that we operated for research was ~220,000 gallon of water (for irrigation and others) for a 10,000 sq ft greenhouse over 10 months. Assuming half of the water use is for fertigation, amounts of fertilizer salts mixed to formulate the hydroponic solution was estimated and converted to a $0.168 per sq ft over 10 months. Water cost (municipal water) was estimated as $0.153 per gallon. Therefore, the total costs for water and fertilizers are $0.321 per sq ft over 10 months of production. When growers wish to use pre-mixed fertilizers instead of mixing their own, the fertilizer cost will be greater.
Substrate costs. This is one of large cost components of consumable materials used in strawberry production. The lowest costs can be achieved when growers mix their own substrates. The needed volume of substrates is 2 liter (half gallon) per plant, and it typically costs between $0.12 – $0.33 per liter ($0.24 – $0.66 per plant). Some growers attempt to re-use substrates, risking presence of previously acquired root-zone diseases and degraded physical and chemical properties of already-used substrates.
IPM costs. IPM can be very expensive depending on the types of control used relative to pests typically problematic in the greenhouse. Our rough estimate based on the usage in our research greenhouse is $0.20 – $0.50 per sq ft over 10 months for controlling thrips and spider mites.
Bees. One class-A hive per greenhouse will be replaced every 3 months during the flowering period. This assumption generated a $0.09 cost per sq ft over 10 months.
Transplants. The per-plant costs for transplants vary from $0.15 for bare root frigo plants to $0.50 for rooted runner tips (plugs). Trayplants are likely more expensive (e.g., ~$1.00 per plant in Europe).
Other consumable materials costs. The other material costs that should be included are those such as 1) plastics used as mulching, 2) fungicide (if needed), 3) disinfectant, and 4) packing materials. The packing materials can be an expensive cost component depending on the package size, type, and design.