Jewish Law
Daily Halacha: Shabbat Guide: Washing Hands and Throwing Pits Outside
Understanding Shabbat halacha about washing hands near plants and discarding fruit pits, based on the rulings of Rabbi Ovadia Yosef

Is it allowed to wash hands in a sink that has a pipe connected to water the garden?
If you're eating outside in a garden, it's not allowed to wash your hands directly over plants or grass. This is because watering them on Shabbat is considered helping them grow, which is not permitted.
However, it is allowed to wash your hands in a sink that has a pipe leading to the garden. Since the water flows through the pipe and not directly onto the plants, this is considered an indirect action, and therefore it's permitted.
(Based on Chazon Ovadia)
Is it allowed to throw pits on the ground?
You are allowed to throw pits or seeds onto dry ground where there is no concern that something will grow from them. But if the soil is moist or soft, where growth is possible, then it is not allowed.
(Based on Shulchan Aruch)
Ach Tov VaChesed – Daily Halacha