Leaves are not likely to catch fire inless there is a bit of broken glass or a bottle nearby! they act as magnifying glasses and can cause a fire via the sun

Are you near a road or track? if so keep the leaves and trimmings away from it, it only takes one carelessly discarded smouldering f*g to start off your pile, and even if it wasn't your fault the fine and the bombers will still charge!!

Tested my new outside boiler today with leaf litter and tree trimmings, it took longer than I thought but I got 150ltrs of hot water 70 deg in 3 hours from one of those cheap stove they sell in Sabecos and Garcias, it was worth the time and money converting it and I can now burn right through the summer and get free hot water, and still have a cool Casita
G.O.M.