The 7Es Scientific Inquiry Through Plant Assay Guide Manual was developed to address the development of science inquiry skills, localization and contextualization among junior high school students. These are some of the requirements of the K-12 science curriculum in the Philippines. However, the developed laboratory manual was not yet implemented and evaluated among the junior high school students. This study was conducted to describe the implementation and evaluation of the developed laboratory manual. In this descriptive research, the respondents were twenty-eight (28) Grade 9 STE students from a public school in a congressional district of the Philippines, school year 2019-2020. During the implementation, five (5) out of eleven (11) procedures in the manual were tried out through a seminar-workshop. The modified evaluation form for Learning Resource Materials (print) from the Department of Education, Philippines and the researcher-made pretest and post-test were used during the evaluation. The results showed that during the implementation, the students actively participated in the seminar-workshop by performing the activities with dedication and enthusiasm. They clarified procedures for them to do the activities correctly. Using the laboratory manual, the knowledge (z=4.35, p=0.00) and skills (z=3.35, p=0.00) of the students on the five biology laboratory procedures implemented significantly increased. The students rated the manual excellent (M=94.4%, SD=2.93). They gained new knowledge and skills on plant identification and collection, extraction of plant compounds, phytochemical screening, cytotoxicity, and allelopathic activity screening of plant extracts. They were able to create topics using plants for their SIPs. They learned that conducting SIPs needs not to be expensive; one can use common materials and can do improvisations. This study offers a manual that could guide students in the conduct of SIPs.