Shorten Post Titles

On our website, PantrySpa.com, if post titles are too long, I want to make them short by cutting them off after a certain number of characters and instead end with "…" so that long post titles won’t break the image grid on the home page / category etc. by running over to three lines. How can I do this?

If it is helpful, I have granted support access through the wpmu plugin.

Thanks for your help!