While some gardeners recommend this, we don’t, and we’ll tell you why. Epsom salt is not something that your plant can use, so it’s not going to absorb it on purpose, and that same salt can end up in the groundwater when it drains. Worse, Epsom salt can actually promote blossom-end rot, and you definitely don’t want that! Stick to your favorite fertilizers during the growing season and leave that Epsom salt in the container where it belongs.