创建描述字段 - 在MySQL数据库中读取和写入它

I'm creating an application with AngularJS and PHP. In that application is a description field, which does not have a character limit. Ultimately I'm trying to save the description field with mysqli, but am having difficulty choosing a datatype.

Because there is no character limit VARCHAR doesn't work. I made the field a BLOB. I don't know how to pass the long text to mysqli if it is a BLOB, nor do I know how to read it and write it into a JSON object, or how to read it in AngularJS so that the text can be loaded back into the textarea after saving.