August is the usual recommended time. You need shoots with no flowers, so you may have to debud them. Strip off the bottom leaves to cut down transpiration loss until they have roots. There seems to be two schools of thought about what to do next. Some people root them in water and some in a fairly dry gritty compost as the are semi succulent. If you use the compost method you can leave them for a few hours for the cut stem to heal over before inserting them in the pot. (I'm assuming you mean pelargoniums and not the outdoor herbaceous ones - if you mean those then you can just split the clumps.) If you overwinter the mother plants indoors you could try taking new shoots in the spring and treating them the same way, but I have never tried this. If you try in the colder weather you may have mildew problems because of the higher humidity.

The advantage with water is that you can root them any time of year (like now). They take about 2 weeks to grow roots, 3-4 to get enough roots to pot up carefully. I keep them in a sunny windowsill till spring.

As per Steragrams instructions I've done both... Overwintered the whole plants in my conservatory and took some cuttings too. I just take cutting, about 2 - 3 leaves from a tip, dip them in rooting powder, although I'm not sure that's necessary. Just pop them into a gritty compost and water very very sparingly.

Remember that Geraniums are basically succulents - hence they root well in water/gritty compost method and they freeze during frost. Ice crystals form inside the plant, they droop and blacken and there is no saving them.

Either wait till spring and get lots of cuttings from an over wintered plant or take some cuttings now - or do both and have lots of little Geraniums.

thank you very much, very informative