Understanding how glutamatergic input translates into dendritic calcium activity is essential for deciphering synaptic integration in cortical circuits. In this project, we used two-photon dual-color imaging to record from L2/3 pyramidal neurons in the mouse primary somatosensory cortex (S1). The initial aim was to investigate the temporal relationship between glutamate inputs, measured with iGluSnFR3, and calcium dynamics, reported by red-shifted genetically encoded calcium indicators (GECIs), in L1 dendrites. As a first step, we tested whether co-expression of iGluSnFR3 with a jRGECO1a could be achieved in the same neurons at a sparse enough density to permit imaging of single dendrites that could be traced back to their dual-expressing soma. This prerequisite was fulfilled, but in these conditions, dendritic jRGECO1a signals were weak or absent during whisker stimulation and following glutamate events, suggesting a reduced indicator performance due to co-expression limitation rather than a lack of physiological activity. Consequently, we performed a systematic characterization of four red GECIs (jRGECO1a, jRCaMP1a, RCaMP3, OCaMP) expressed individually in L2/3 pyramidal neurons. RCaMP3 exhibited the highest somatic sensitivity and dynamic range, OCaMP provided strong dendritic signals and superior photostability, jRGECO1a performed intermediately, and jRCaMP1a showed limited functional sensitivity. These results establish a quantitative basis for selecting calcium indicators in dual-color experiments. Taken together, our findings identify RCaMP3 as the most balanced candidate for future co-expression with glutamate sensors, enabling refined exploration of the spatiotemporal coupling between glutamatergic inputs and dendritic calcium responses in vivo.