Tomato Harvest Forecast requires a minimum of 40 stems measured twice per week for cultivations of 1 hectare or more. For smaller cultivations (under 8,000 m2), 20 stems measured twice per week is the minimum.
Key rules:
Spread measurement plants across the full greenhouse. Do not cluster in one section.
Use the same plants each week. Switching plants between sessions introduces noise.
Measure different individual plants rather than multiple stems on the same plant. Four stems from four different plants provide more information than four stems from one plant.
Measure twice per week. Once per week is the minimum Source can work with, but accuracy drops.
For a detailed guide on selecting representative stems, replacing measurement plants, and recognizing signs of non-representative measurements, see How to conduct plant measurements for Source Cultivate.
If your forecast is consistently too high or too low and your strategy settings are correct, measurement representativity is the most common remaining cause. Start a chat conversation within Workspace and ask for your AISS if you suspect your measurement plants are not representative.