Get entries by date range from plugin
Ok, found an answer that made it a bit clearer:
How do I get elements using getCriteria from a specific date?

Basically you can do this:

$criteria = craft()-&gt;elements-&gt;getCriteria(ElementType::Entry);
$criteria-&gt;postDate = '&gt;'. date('Y-m-d', strtotime("-4 weeks"));
$result = $criteria-&gt;find();


To get Entries form a month back.