The park is open daily between 8am and 7.30pm. Keukenhof works with time slots of half an hour as arrival time.
So you can choose from time slots like: 8.00 – 8.30 am, 8.30 – 9.00 am. The last time slot is 6 pm – 6.30 pm (Please note that the park closes at 7.30 pm. This means you can stay in the park for a maximum of an hour and a half).