Spiraea arguta, S. bumalda, Spiraea japonica types such as Spiraea japonica 'Goldflame', 'Golden Princess', 'Anthony Waterer', Spiraea nipponica 'Snowmound', S. thunbergii, Spiraea vanhoutei, and also Spiraea veitchii.
Here a Spiraea Snowmound - just finished flowering (Late June). Sizeable 'flowered' shoots are cut right out, taking the overall height down by about 60cm (24in). It will regain this height again during the next few months, with plenty of flowering growth ready for next year. Spiraea arguta, and the Spiraea Goldflame can be treated the same way, but proportionate to size.
(If desired, they can be cut right back to within a few cm of the ground! It is good practice to also cut back a proportion of the main stems - Prune back to ground level, or just a few centimetres above. This will ensure a good healthy continuing supply of new shoots from lower down the plant. These new shoots will flower in subsequent years. Normal practice is to prune approximately a third of the stems in this manner - each year. It follows that at the end of year three, there will be no 'old' stems left, after this type of pruning Spiraeas.
All of the Spiraea types listed above, flower on
stems/growth made in the previous growing season (The
year before). If you prune them in the spring ie
before flowering - then you will be cutting off all of
the flowering stems and flower buds for the current
year, and will end up with no flowers!