My Deutzia shrubs have not bloomed well the last two years -does it need feeding, pruning or what.
Perhaps you are having a problem with pruning. Because Deutzia flowers on the previous year's growth, right after flowering the spent flowers should be pruned back to strong buds. In addition, the oldest shoots (perhaps as many as a third of the stems) should be cut back to near ground level to encourage new growth. If you are concerned about fertilizing the plants, a top dressing of compost ought to do the trick.