Where to measure Soil Moisture relative to plant

Hello all,

I am with the AlphaGarden team out of UC Berkeley that is working to make a fully autonomous garden and we were hoping to receive some guidance on where an optimal place is to measure soil moisture level relative to a specific plant.

We want to measure the soil moisture level for every plant. We water the plants in our garden at the same z level (300 mm) every day (our dirt level is -120 mm), and we have a sequence of (x,y) coordinates corresponding to each plant. We noticed the water nozzle is fairly accurate and waters a finite region around each plant. Thus, if we measure too far from said (x,y), our soil moisture level will not be accurate as the dirt is nearly dry. However, we also do not want to harm the plant by taking a measurement that is too close.

Has anyone experimented with this before and discovered an optimal system that measures accurate soil moisture levels without harming the plants? Maybe a simple offset of the x coordinate? Also, how long should we wait before taking a measurement after watering? All suggestions are appreciated!


Hey @markt,

It is kinda different for different plants once they have matured. But for seedlings I would say a 2-3cm radius (x or y offset). Small pot plants size, which are say max 15cm high at a 5cm radius. After that most deep root plants you could do 5-10cm radius depending on the foliage. Oh and obviously measure moisture more in summer less in the other seasons. So in summer measure 6 to 12 hours after watering and make the the hours after watering longer in winter etc.

Hope that helps,