Hydroponic Tomato Growth: Economics

Getting started with the economic budget analysis spreadsheets

The economic budget analysis spreadsheets are in Microsoft Excel format.  They make heavy use of macros, and as such, there is no guarantee that they will work in other applications, such as Open Office (although, they do appear to work fine.)  There are budgets for single-bay greenhouses (recommended for beginners), and multiple-bay greenhouses.  The spreadsheet allows users to modify values for various costs and returns so that they may see how a price change will affect their annual return on investment.  The return is updated immediately, so the user may see how the changes affect the end result.  One of the most valuable features of this budget analysis is that users will be able to see how changing some prices will have a dramatic effect on the return, while changing others might have very little effect on the profit margin.

Getting Started

The first thing to do is to download either the single-bay or multiple-bay budget analysis spreadsheet for your desired crop.  You may receive alettuce budget thumbnail warning that the file contains macros, and it will ask if you wish to enable or disable the macros.  In order to obtain the full functionality of the spreadsheet, you will need to have the macros enabled.  In some instances, a dialog box may appear, asking for a username and password.  If this happens, simple click ‘Ok’ until the spreadsheet loads.

Once the spreadsheet has loaded, you will see a number of colored cells (e.g. green for lettuce and red for tomato.)  These indicate values that the user may change.  At the top of the sheet is a yellow row which will always stay in place to show the return on investment.

The single-bay and multiple-bay versions of the spreadsheets are, for the most part, identical.  In fact, if 1 bay is used in the multiple-bay spreadsheet, the results will be the same as the single-bay version.  The significant difference between the two is that the multiple-bay version has the additional group where the user may enter the desired number of bays.  This will update the total area of the greenhouse.  Changing the number of bays will update some of the user-modifiable values, such as fuel usage and the greenhouse control equipment, to reflect the increased area.  It is important to note that this change simply provides a starting point for working with the new bay count.  Users are urged to make changes to the spreadsheet accordingly.  For example, a user may decide that they do not need a backup generator or environmental control computer for each bay.

Variable Cost Auto AdjustYou may notice a line such as the image to the left.  The variable cost auto-adjust (when on) will automatically adjust the necessary costs based on the number of turns (harvests) you enter for the year.  The default values were calculated using a default number of turns (e.g. 10 turns).  It will generate a ratio for any value above this default, and multiply the costs by the ratio.

Fuel ChoiceThere is the fuel selection options.  You may choose from Fuel Oil, Liquid Propane, or Natural Gas for this exercise.  Depending on which fuel you select here, all values in the sheet pertaining to fuel costs will be updated to reflect this choice.


Grow LightsThere is also the option to use grow lights.  If grow lights are desired, the user may select 1000W Metal Halide or Sodium lights.  Using grow lights will allow for a higher number of turns per year (for instance, lettuce can increase from 10 turns to 12 turns.)


The spreadsheet should be used to help gain an understanding of how budget analysis might work for a hydroponic operation.  This is just an example, and should not be used as an actual budget predicion.