Not with CSS you can't. You need to use JS. A quick example copying the img to the background:
var $el = document.getElementById( 'rightflower' )
, $img = $el.getElementsByTagName( 'img' )[0]
, src = $img.src
$el.innerHTML = "";
$el.style.background = "url( " + src + " ) repeat-y;"
Or you can actually repeat the image, but how many times?
var $el = document.getElementById( 'rightflower' )
, str = ""
, imgHTML = $el.innerHTML
, i, i2;
for( i=0,i2=10; i<i2; i++ ){
str += imgHTML;
}
$el.innerHTML = str;