Unlike piano players, dulcimer players need to learn how to tune their own instruments. Tuning requirements for hammered dulcimers can vary immensely. Factors that influence an instrument's tuning stability include the integrity of its construction, temperature fluctuations, and, to a lesser degree, changes in humidity. A well-built, stable instrument will hold its tune for weeks, sometimes longer, when kept in a fairly constant environment such as a home. If you take this instrument from a warm house to a cold car and back again, it will probably need some tuning once it warms up in the new atmosphere.
Tuning is not a difficult process. With practice and the help of a chromatic electronic tuner and clip-on tuner pickup, it may take up to 15 minutes for a complete top-to-bottom retuning.