How do I make an item with the property of bone meal?

If you want this item to affect vanilla minecraft trees or seeds I think you will need to code that, if you want this item to affect your custom mod elements you just need to create a procedure inside each element(custom seed or sappling) for right clicking if player has this item in main hand do random chance to destroy the block and set the next stage of this block on the same x y z, do this procedure again for the next stage element and so on until the seed or tree is full grown 

If you want this item to affect vanilla minecraft trees or seeds I think you will need to code that

To extend, if you know how to code this will prove helpful;

   public static boolean applyBonemeal(ItemStack stack, World worldIn, BlockPos pos, net.minecraft.entity.player.PlayerEntity player) {
      BlockState blockstate = worldIn.getBlockState(pos);
      int hook = net.minecraftforge.event.ForgeEventFactory.onApplyBonemeal(player, worldIn, pos, blockstate, stack);
      if (hook != 0) return hook > 0;
      if (blockstate.getBlock() instanceof IGrowable) {
         IGrowable igrowable = (IGrowable)blockstate.getBlock();
         if (igrowable.canGrow(worldIn, pos, blockstate, worldIn.isRemote)) {
            if (worldIn instanceof ServerWorld) {
               if (igrowable.canUseBonemeal(worldIn, worldIn.rand, pos, blockstate)) {
                  igrowable.grow((ServerWorld)worldIn, worldIn.rand, pos, blockstate);
               }

               stack.shrink(1);
            }

            return true;
         }
      }

      return false;
   }

(taken from BoneMealItem)