The past participle is planned.
Planned is the past participle of plan.
The past participle of the word "pick" is "picked".
Planned is the past participle. (It is also the simple past tense form)
The past participle of the word "have" is "had."
The past form (and also the past participle) of plan is planned.
The word "it" does not have a past participle as it is a pronoun. It is only verbs that have a past participle.
The past participle of the verb to have is had.
The past participle of the word "do" is "done."
The past participle of the word "Find" is the word "Found."
The past participle of "plan" is "planned."
The past participle of the word graduate is graduated
The past participle of the word 'fall' is 'fallen'.