The first three gardens open daily from 9am to 6pm. Admission is free on weekdays and you have to pay RM1 on weekend and public holidays.
Rimba Ilmu, a botanical garden, is situated in Universiti Malaya Kuala Lumpur, opens from 9am to 12pm; 2pm to 4.30pm on weekdays. Admission for adult is RM4 and children RM2. They also open on First Saturday from 9am to 12pm and offer guided tour to the garden. Closed on other weekends. Plants are labeled accordingly so that you know what are the species.
More information about Rimba Ilmu can be found here: Rimba Ilmu Botanic Garden or UMique Rimba Ilmu. Please refer to the map before going. My son and I were lost during the trip and we had to make two trips around the university area before we found two students sitting by a bus-stop and asked them for direction. By the time we reached Rimba Ilmu, it has been closed for lunch. My son and I went straight home as he is not the type to wait for two hours ^__^