According to GardenGuides.com, lavatera plants should be pruned in early spring. To best promote new growth and shape the plant, the previous year's growth must be pruned down to 10 inches from the plant's base in areas that survived the winter.
Dead branches must also be pruned as they are noticed, and frost-damaged branched should be cut back to normal growth. The annual plants should then be fertilized every two weeks during the summer growing season. To encourage lively growth, generous watering is necessary throughout the hot summer months when total rainfall amounts to less than 1 inch per week.