What does your garden need?
With the Growers Toolbox you see straight away, with no form and no waiting, how much water your crop needs, which growth stage you are in and which smart devices suit you.
No form. Instant answer.
In the past you got in touch and waited for a callback. Now you pick your type of crop and see in an instant how much water you need, which growth stage you are in and which smart devices fit. Simple for the allotment, advanced for the experts.
Calculate your water needs in 30 seconds
Allotment or rose nursery, greenhouse or open ground: tell us briefly what you grow and the toolbox instantly works out your water needs, your watering schedule, the reservoir and the recommended Zigbee set. Switch between simple and advanced with a single tap.
Water needs change with each growth stage
A young plant drinks the least, most when it flowers and sets fruit, and less again as it ripens. Click a stage and see what happens. Flip the switch to advanced for the BBCH codes, crop coefficients and growth models.
Sources and scientific basis
The advanced mode uses no rules of thumb but recognised, peer-reviewed methods. Below is the primary source for each calculation step. In science, only what is traceable counts, so every equation and table value can be looked up.
The water need follows the FAO standard: crop evapotranspiration ETc = ETo × Kc, with the reference evapotranspiration according to Penman-Monteith and, for the Netherlands, the Makkink standard of the KNMI. The soil water balance (TAW, RAW, watering interval) comes from the same FAO-56 guideline. Salinity follows the model of Maas and Hoffman, the temperature sum that of McMaster and Wilhelm. For growth under glass we refer to the work of Stanghellini.
- Allen, R.G., Pereira, L.S., Raes, D. & Smith, M. (1998). Crop evapotranspiration: guidelines for computing crop water requirements. FAO Irrigation and Drainage Paper 56. FAO, Rome. fao.org/4/x0490e. Source for ETo (Eq. 6), Kc correction (Eq. 62/65), TAW/RAW (Eq. 82/83) and Table 19/22.
- Penman, H.L. (1948). Natural evaporation from open water, bare soil and grass. Proceedings of the Royal Society A, 193, 120-145. doi:10.1098/rspa.1948.0037
- Monteith, J.L. (1965). Evaporation and environment. Symposia of the Society for Experimental Biology, 19, 205-234.
- Makkink, G.F. (1957). Testing the Penman formula by means of lysimeters. Journal of the Institution of Water Engineers, 11, 277-288.
- De Bruin, H.A.R. (1987). From Penman to Makkink. In: Hooghart, J.C. (ed.), Evaporation and Weather, CHO-TNO Proceedings 39, 5-31. Introduces the KNMI constant c = 0.65.
- Hooghart, J.C. & Lablans, W.N. (eds.) (1988). Van Penman naar Makkink; een nieuwe berekeningswijze voor de klimatologische verdampingsgetallen. CHO-TNO Rapporten en Nota’s 19 (also KNMI TR-111), The Hague.
- Maas, E.V. & Hoffman, G.J. (1977). Crop salt tolerance: current assessment. Journal of the Irrigation and Drainage Division (ASCE), 103(IR2), 115-134. doi:10.1061/JRCEA4.0001137
- McMaster, G.S. & Wilhelm, W.W. (1997). Growing degree-days: one equation, two interpretations. Agricultural and Forest Meteorology, 87(4), 291-300. doi:10.1016/S0168-1923(97)00027-0
- Meier, U. (ed.) (2001). Growth stages of mono- and dicotyledonous plants. BBCH Monograph, 2nd edition. Federal Biological Research Centre for Agriculture and Forestry (BBA), Germany. Open access (2018): doi:10.5073/20180906-074619
- Steduto, P., Hsiao, T.C., Raes, D. & Fereres, E. (2009). AquaCrop, the FAO crop model to simulate yield response to water: I. Concepts and underlying principles. Agronomy Journal, 101(3), 426-437. doi:10.2134/agronj2008.0139s
- Allen, R.G. & Pereira, L.S. (2009). Estimating crop coefficients from fraction of ground cover and height. Irrigation Science, 28(1), 17-34. doi:10.1007/s00271-009-0182-z
- Stanghellini, C. (1987). Transpiration of greenhouse crops: an aid to climate management. PhD thesis, Wageningen Agricultural University. doi:10.18174/202121
- Katsoulas, N. & Stanghellini, C. (2019). Modelling crop transpiration in greenhouses: different models for different applications. Agronomy, 9(7), 392. doi:10.3390/agronomy9070392
- Ayers, R.S. & Westcot, D.W. (1985). Water quality for agriculture. FAO Irrigation and Drainage Paper 29 Rev.1, Rome. Reproduces the salt tolerance table of Maas and Hoffman.
What is the Growers Toolbox?
A set of practical tools that answer growing questions instantly, starting with a water-needs calculator. No form to fill in, just an answer.
How does the water calculator work?
You enter a few details about your plot and it estimates your water needs in about 30 seconds, adjusted for the growth stage your crop is in.
Why does water need change with growth stage?
Plants use water differently as they develop, so the calculator factors in the stage to give a more realistic figure than a fixed amount.
Is the advice based on real science?
Yes. The calculations draw on recognised sources and a scientific basis, which are listed on the page.
Do I need an account to use the tools?
No. The tools give an instant answer with nothing to sign up for. For live data from your own site, see sensors.
Can FairGrow do this automatically?
Yes. With your own sensors, FairGrow tracks conditions live and keeps advising you as things change. See how it works.