Technical Abstract: Inclusion of Silicon (Si) in fertilizer solutions is not a typical management practice in floriculture crop production in the United States, in spite of the growing body of literature showing a clear, beneficial effect on plant growth for some species. We have evaluated Si uptake in 46 crops utilizing hydroponics with and without Si in the nutrient solution using inductively coupled plasma optical emission spectroscopy analysis. Roughly 50% of the species tested had Si concentrations higher than 0.1% dry weight in the leaf tissue. Fertigation is effective, but mixing can be expensive and require additional pH management. We have investigated applying a Si-containing industrial mineral byproduct, generally referred to as slag, as well as Si-containing plant materials like rice hulls and biofuel crop residue. Additionally, we have investigated commonly encountered materials and solutions for their “background” Si concentrations in order to minimize contamination. Using the Si-accumulating species zinnia and sunflower as model crops, comparable amounts of Si could be supplied to plants when Si-containing plant materials were incorporated into the substrate compared to unamended but fertigated control plants. Finally, several diverse systems have been utilized to investigate the function of Si in plants. For example, the role of Si in plant responses to Cu stress was investigated in the floriculture crop Zinnia elegans. Based on visible plant symptoms and dry weights in zinnia, Si was found to alleviate copper stress. Furthermore, zinnia showed a reduction in PAL (phenylalanine ammonia lyase, a stress-induced enzyme) activity, suggesting Cu stress decreases in tissue exposed to supplemental Si. Cu concentrations inside the leaf were significantly lower in Cu+Si treatments compared to Cu toxicity treatments alone. Additional functions for Si include minimizing or delaying powdery mildew in zinnia. Together, this information has served in identifying species of floriculture crops that may benefit from supplemental Si during production as well as sources of Si for economical application of Si to floricultural crops, which could result in higher quality plants with fewer and less expensive agrochemical inputs.