replace

index.php:

$smarty = new Smarty;
$smarty->assign('articleTitle', "Child's Stool Great for Use in Garden.");
$smarty->display('index.tpl');

index.tpl:

{$articleTitle}
{$articleTitle|replace:"Garden":"Vineyard"}
{$articleTitle|replace:" ":"   "}

OUTPUT:

Child's Stool Great for Use in Garden.
Child's Stool Great for Use in Vineyard.
Child's   Stool   Great   for   Use   in   Garden.