hi bunny, by "clumping" it sounds like you are after the shrub geraniums or zonal pelargoniums, the weaving ones will often be called things like ivy geranium, climbing or trailing geraniums. hope that helps.

G. cinereum and G. sanguineum and their cultivars make small mounds and flower most of the summer. Trailing/climbers would be G wallichianum and it's cultivars and G. 'Rozanne'. Climbing isnt the right word but scrambling through a near by plant is right.

G. macrorrhizum is strongly clumping, I would say.

Gata, doesnt yours run around? even a wee bit?