Research on chipless and passive architectures for environmental sensing is generating high interest because they do not require any semiconductor components or batteries to operate, thus resulting in an eco-friendlier footprint. This study demonstrates a printed microstrip line with multiple resonators using biodegradable materials to continuously monitor temperature and relative humidity (RH). Constructed with a paper substrate and printed zinc conductive lines, and encapsulated with beeswax to protect against the interference of humidity, the microstrip line integrates spiral-shaped resonators. One resonator operates at 1.2 GHz for temperature sensing, while another, coated with konjac glucomannan serves for relative humidity sensing at 2 GHz. The multi-resonating features allow for a simultaneous assessment of temperature and humidity. The microstrip line displays a linear sensitivity to temperature of −1.35 MHz °C−1 and a non-linear relative humidity sensitivity ranging between −0.8 and −8 MHz/%RH from 30% to 70% RH. Its degradation in a lab-made compost for 70 days shows the removal of the transducing layer in 7 days and degradation of the cellulosic substrate starting after 5 weeks. The developed environmental sensing devices are notably promising for future applications in smart packaging and the tracking of goods aiming at the minimization of electronic waste.