Whether you want to boil a zucchini to enjoy it with a bit of butter or seasoning or need a partially cooked squash to incorporate into a dish, the size of the squash proves important. The larger the zucchini happens to be, the longer you should boil it on the stove top to help it reach the correct degree of tenderness.
Fill a medium-size pot half full of lukewarm tap water and 1 tsp. of salt and place it on the stove top on "high" to bring to a boil. Rinse the zucchini well with clean water and scrub the skin with your fingers.
Carefully place the whole zucchini in the pot of boiling water.Turn the pot of water down to a medium-high setting. The water should still be boiling.
Set a timer for 5 to 15 minutes to allow the zucchini to boil, depending on the size of the zucchini and the degree of tenderness you desire. Test the zucchini with a fork before removing the pot from the heat and draining.
If you plan on stuffing the zucchini and cooking it in the oven after boiling, you'll want to boil only until it's barely tender.