Taking the advice of Śrī Caitanya Mahāprabhu and our spiritual master, Bhaktisiddhānta Sarasvatī Gosvāmī Mahārāja, one can go to any part of the world and instruct people to become devotees of the Lord by following the regulative principles, worshiping the tulasī plant and continuously chanting the Hare Kṛṣṇa mahā-mantra.
(Sri Caitanya Caritamrta------2:24:261-----purport).

In the Skanda Purāṇa there is a statement praising the tulasī tree as follows: "Let me offer my respectful obeisances unto the tulasī tree, which can immediately vanquish volumes of sinful activities. Simply by seeing or touching this tree one can become relieved from all distresses and diseases. Simply by offering obeisances to and pouring water on the tulasī tree, one can become freed from the fear of being sent to the court of Yamarāja (the King of death, who punishes the sinful). If someone sows a tulasī tree somewhere, certainly he becomes devoted to Lord Kṛṣṇa. And when the tulasī leaves are offered in devotion at the lotus feet of Kṛṣṇa, there is the full development of love of Godhead."
In India all Hindus, even those not belonging to the Vaiṣṇava group, take special care of the tulasī tree. Even in great cities where it is very difficult to keep a tulasī tree, people are to be found very carefully keeping this plant. They water it and offer obeisances to it, because worship of the tulasī tree is very important in devotional service.
In the Skanda Purāṇa there is another statement about tulasī, as follows: "Tulasī is auspicious in all respects. Simply by seeing, simply by touching, simply by remembering, simply by praying to, simply by bowing before, simply by hearing about or simply by sowing this tree, there is always auspiciousness. Anyone who comes in touch with the tulasī tree in the above-mentioned ways lives eternally in the Vaikuṇṭha world."
(Nectar of devotion).

Prabhupāda: Better than Viṣṇu worship is to worship Vaiṣṇava. Tadīyānām ārādhanam. Tadīyā means His servant, or one who is, or what is in relationship with Him. Just like we areworshiping this plant, Tulasī. We are not worshiping all plants, but because this Tulasī has very intimate connection with Kṛṣṇa and Viṣṇu, therefore we are worshiping. Tadīyānām ārādhanam.
(Room Conversation by Srila Prabhupada).

Siddha-svarūpānanda: Tulasī grows profusely in Hawaii.
Prabhupāda: That's a good sign.
Siddha-svarūpānanda: Yes. Many people, hundreds of people, are worshiping tulasī. Even people we don't know, they, somehow or other, they have gotten tulasī, and they are worshiping.
Prabhupāda: Very good. They will become devotee. Without any fail, they will become devotees. If they chant Hare Kṛṣṇa and worship tulasī leaf, they'll be liberated without any fail, and they will become devotee.
(Morning walk conversation).

Prabhupāda: When Pārvatī inquired from Lord Śiva what is the best form of worship, he advised, viṣṇor ārādhanaṁ param: "Oh, to worship Lord Viṣṇu is the best form of..." Then he said, tasmāt parataraṁ devi tadīyānāṁ samarcanam: "And greater than viṣṇor ārādhana, Viṣṇu worship, is to worship tadīyānām, anything in connection with Viṣṇu." Anything.... That is Vaiṣṇava. Just like we are worshiping tulasī, tulasī plant. Why tulasī plant? It is a plant only, not even human being. Tadīyānām. Because tulasī is liked by Kṛṣṇa. Similarly, anything in connection with Viṣṇu, to worship, that is better than Viṣṇu worship.
(Morning walk conversation).

I am very glad to know that you are seriously taking to Srimati Tulasi Devi worship. Tulasi Devi is a pure devotee of Krishna and she should be treated with the same respect given to all Krishna's pure devotees. Simply by worshiping her faithfully, a devotee can get himself free of from all material miseries. In the Nectar of Devotion I have given two verses from the Skanda Purana, one of which is: "Tulasi is auspicious in all respects. Simply by seeing, simply by touching, simply by remembering, simply by praying to, simply by bowing before, simply by hearing about, or simply by sowing the tree, there is always auspiciousness. Anyone who comes in touch with the Tulasi tree in the above mentioned ways lives eternally in the Vaikuntha world." So from this verse we can understand how pure is the service which Tulasi offers to Sri Krishna. So we should always endeavor after becoming servant of Tulasi Devi. I do not know who has taught you that part of a Tulasi plant may be cut off and then replanted? From the Tulasi plant you can cut off only leaves for offering them to Krishna, never for cutting and planting. That is an offense. The manjaris (seeds) can be offered in water and it makes the water fragrant and tasteful. And the manjaris can be planted for growing new Tulasi plants. Yes, the prayer you have enclosed is bona fide. Tulasi Devi never goes back to Godhead, she is always with Godhead. She is a pure devotee and thus she has appeared on this planet to render service to Krishna by being offered in all temples throughout the world by being offered up to the lotus feet of Krishna.
(Letter to Radhavallabha by Srila Prabhupada).