One of the easiest methods is to measure the increasing height per day. For comparing different spicies you standart the measuring with the maximal height of the species.
Shrubs and subshrubs like salvia are sensitive to root restriction. Details for growth analysis can be like in a specific report hortsci.ashspublications.org/content/32/7/1186.full.pdf
Measuring plant height of different wild species every day after emergence will be helpful. Moreover, try to measure relative growth rate of all species to have better idea regarding their growth.