My lawn sprinkler is automatic. Is it allowed on Yom Tov or chol hamoed? I have a service that takes care of it. Second, I have a lawn service that comes whenever they want to. They do several houses on my block. Do I have to stop them from coming on Yom Tov or chol hamoed?

Shalom, Thank you for your question. An automatic sprinkler system that is set before Shabbat or the festival is permitted to turn on and water the lawn both on Shabat, Yom Tov and Chol HaMoed. As to the non Jewish lawn service that take care of the lawn on Shabat and Yom Tov. In general it is forbidden to employ a non Jew to do forbidden labor for us on Shabat (except in certain cases for the needs of a community or mitzvah, or for the sick or frail). Even when the employment is not for a specific time, but the non Jew decides to do the work on Shabat or Yom Tov because that is more convenient for them, it is still forbidden if done in the Jews house (as opposed to work done by the non Jew in their own house or shop). This is because there is reason to suspect that people will think that the Jew told the non Jew to carry out the work on Shabat (which is certainly totally forbidden). (See Shmirat Shabbat KeHilchatah 20, 31-32). This means that one is not allowed to have non Jewish lawn workers service their garden on Shabat or Yom Tov. One is obligated to protest their working on those days – so you should organize to change the days from Shabbat and Yom Tov to other days. If they non the less turn up you should request they stop working. As to Chol HaMoed – it is also forbidden to allow the lawn service to work in Chol HaMoed (see Zikron Shlomo, page 102 in the name of Rav Moshe Feinstein zt”l). However, work that needs to be done to ensure that the garden does not die, such as watering, is permitted to be done on Chol HaMoed, even by a Jew, and also by a non Jew lawn service.