- var_dump: documentation ( source)
- date_create_from_format: documentation ( source)
<?php
$start = '2014-01-01 00:00:00';
$date_res = date_create_from_format('Y-m-d H:i:s', $start);
$date_end = $date_res->add(new DateInterval('PT' . 10 . 'M'));
var_dump($date_end->format("Y-m-d H:i:s")); echo "<br>";