Yellow Geranium Cuttings.
Yellow geranium cuttings I think your best bet is to sacrifice one of the cuttings and see what is happening at the end that is in the soil.If it looks squishy and there is signs of mould then remove all the yellow ones.With cuttings it is generally a race between root and rot.
However it may just be that they are a bit hungry. Cutting composts are always low on food so that potential roots do not get scorched by the added fertilizers. That is why John Innes have the full range from seed to No 3. Each one has more fertilizer.If it is yellowing due to hunger I would not be inclined to feed before mid March or April.You could perhaps give them a very light foliar feed then. In any case if they have rooted by then then you will be thinking of potting them up then.