I learned that Sn is one of the heavy metal, but so far I haven't see any literature specifically mentioned the impact of Sn toxicity on plant. Most studies report on Al, Cu, and more. If there's literature, please let me know.
Ashraf, M. A. (2013). Evaluation of natural phytoremediation process occurring at ex-tin mining catchment.
Ang, L. H., Tang, L. K., Ho, W. M., Hui, T. F., & Theseira, G. W. (2010). Phytoremediation of Cd and Pb by Four Tropical Timber Species Grown on an Ex-tin Mine in Peninsular Malaysia. studies, 2, 4.
Ashraf, M. A., Maah, M. J., & Yusoff, I. (2011). Heavy metals accumulation in plants growing in ex tin mining catchment. International Journal of Environmental Science & Technology, 8(2), 401-416.
From my understanding based on experience with alluvial tin mining in Australia, the target resource is tin oxide and that this is very geochemically stable. This form would not be expected to generate high bioavailable concentrations. If tin is co-hosted with other metal minerals they are more likely to cause the problems. There is very little in the literature (which in itself suggests there isn't much of a problem. I did come across a paper form Poland that looked at bioavailability http://www.e3s-conferences.org/articles/e3sconf/pdf/2013/01/e3sconf_ichm13_08005.pdf
Are you looking at mine rehabilitation? if so I would think Tin is not your worst issue.