The vast majority of rock and water plants thrive best in sunny conditions, and it may be hard to find a suitable spot in a small garden.  If you can’t find a spot that is in the sun for at least half the day it might be better to choose a water feature that depends less on plants for it’s effect, and to grow your rock plants in otherways, such as between paving, in raised beds or in a gravel garden.  

Very small ponds are much more difficult to balance biologically than large ones, and green water can be a problem for much of the year without proper design.  If the garden is very tiny choose a bubble fountain, wall spout, container pond or small water feature instead.  

Rock gardens look best on natural slope or built to look like a natural outcrop of rock in a large lawn.  Combining the rock feature with the pond is a good idea because you can create the raised ground from the soil excavated for the pond and incorporate a water fall for aeration and effect.  

Rock plants offer huge scope because you can plant dozens in the space taken by just one medium sized shrub creating a miniature landscape. Be careful when choosing water plants.  Some irises and rushes have a compact habit while others can be rampant and take over the whole pond.  There are some lilies that like deep water and a large surface area and others will be happy in 9 inches of water in a small pond.