First I want to start by saying that I'm living in a rental property so I'm trying to do this for as cheap as possible, i.e. free as opposed to buying any type of soil/dirt. The yard wasn't horrible by any means, but still would like to fix it up a bit as I don't know how long I will be here and I enjoy a nice yard. I have already done much more than what the average tenant would do.
There are a couple of holes in the ground on the side of the yard, no grass in these spots, essentially landscaped with mulch, or an area where there are a few flowers. I want to fill the holes in with a pile of leaves that aren't fully composted yet but are better than nothing. In addition, I have some ash from some yard waste that I've taken down. Much of the ash was weeds of some type, Tree of Heaven, some other tree that was cut down but not killed and had many little things growing out of the stump, other random weeds that I did not identify. I know ash can be used as a fertilizer as it contains some nutrients. If I mixed this ash in with the half composted leaves would it lead to the same weeds growing like crazy in the area or can I assume that the weeds are completely dead after they have been burnt? Is this a good idea to try and mix them to get something a little more solid to fill the holes in?