The Compendium of Caraka 7.1.10

7.1.10

tatra yāni &kālajātānyupāgatasaṃpūrṇapramāṇa-rasavīrya-gandhāni kālātapāgnisalilapavanajantubhiranupahatagandha-varṇa-rasa-sparśa-prabhāvāṇi pratyagrāṇyudīcyāṃ diśi sthitāni; teṣāṃ śākhāpalāśamaciraprarūḍhaṃ varṣāvasantayorgrāhyaṃ, grīṣme mūlāni śiśire vā śīrṇaprarūḍhaparṇānāṃ, śaradi tvakkandakṣīrāṇi, hemante sārāṇi, yathartu puṣpaphalamiti; maṅgalācāraḥ kalyāṇavṛttaḥ śuciḥ śuklavāsāḥ saṃpūjya devatā aśvinau gobrāhmaṇāṃśca kṛtopavāsaḥ prāṅmukha udaṅmukho vā gṛhṇīyāt//

There, [those medicines] that are born in due season, have attained full measure, taste, potency, and smell, whose smell, color, taste, touch, and specific action have not been damaged by time, sunlight, fire, water, wind, or vermin, and which are fresh and situated in the northern direction: their branches and tender leaves should be gathered when newly sprouted in the rainy and spring seasons; roots in summer or winter when the leaves are fallen or just grown; bark, tubers, and latex in autumn; heartwood in dewy season; flowers and fruits according to the season. Observing auspicious conduct, of beneficial practice, clean, dressed in white, having worshipped the deities, the Aśvins, cows, and brāhmaṇas, having fasted, facing east or north, one should gather them.