ท่าน thàn is a very formal word to say “you.” It's commonly used when you're talking to someone you respect or who's of a higher status. For example, สวัสดีครับท่าน.
Tightness or heaviness in the chest can result from various mental and physical health conditions, including stress, muscle strain, and lung complications.
 The soil should be really warm, though, if the evenings are still cool, so make sure where you plan to plant gets at least 8 hours of direct sun a day.