Shotgun approaches or targeted SRM analyses have dominated proteome studies as tools to find changes in the proteome. These approaches, however, focus just on the proteins that are changing in abundance in order to find biological insights. They also require statistically significant changes in the total accumulated protein pool size in order to identify that ‘anything has occurred’. Analysing protein synthesis and degradation rates with progressive stable isotope labelling provides a new window on the control of protein abundance. With this approach we can determine the ‘relative age’ of the proteins that we see and define the energetic effort employed by the cell to build or maintain particular activities. We are using progressive ¹⁵N labelling of plant cells from nitrate and ammonia salts and modelling incorporation fits, to calculate the rate at which proteins which are often static in abundance in the proteome are turning over. We have developed pipelines to undertake these studies in plant cells, plant leaves and in whole plants through the use of hydroponics. Projects assessing the impact of leaf age, phosphate limitation and groundwater salinity on protein turnover changes in plants will be discussed. Through combining such labelling with separation of protein complex and subcomplexes by native electrophoresis, we can observe the in vivo turnover rate of assembly intermediates of protein complexes. Combined there approaches provide new avenues for peptide mass spectrometry to provide answers to a wide range of questions in plant biology, and allows researchers to assess the cost of environmental factors on protein turnover and plant growth efficiency.