PHP If/else statement with formatted date to determine the part of the day

I am trying to make a simple if/else statement in PHP. Someting simple like this:

<?php 
$time = 13;
if ($time < 12) {
  echo "Morning";
} else {
  echo "Afternoon or evening";
}
?>

The problem is the value i receive from the database is an unformatted time format (like: 2014-09-08 06:00:00). I can format this date using:

$time->format('H');

To strip the date from the day, month and year. But you can not use this as a variable. This is what i am trying to do:

<?php $deliverytime = new DateTime('2014-09-08 06:00:00');
$deliverytime->format('H');
if ($deliverytime < 12) {
  echo "Morning";
} else {
  echo "Afternoon or evening";
}
?>

I now this is not working because i am trying to use a formatted date as a variable which does not work. Is there another way to determine the part off the day using a formatted date?

Regards, Matthijs