Alkali-activated binders are increasingly being used to produce the prefabricated building materials used in the natural environment. The purpose of this work was to determine the effect of the slag-alkali binder on the growth of two plants: rye and chives. Selected plants were subjected to biometric analysis and macroscopic evaluation. The pH of the soil, the content of sodium ions in the soil, and the plants were also determined. Based on the results of the tests, it was found that the slag binder activated with the NaOH solution does not negatively affect the development course of the plants. It was also examined whether the type of plants, due to the uptake of minerals, influences the change in the compression strength of the tested mortars.