Plants are an essential part of your dragonfly pond. Submerged plants that grow entirely under water are important for developing larvae. Floating plants with leaves that rest on the water's surface are important perches for adults. Emergent plants, which take root at the bottom of the pond but have stems that poke up out of the water, are important perches for larvae to climb up when they are ready to emerge as adults. Then you have your marginal or shoreline plants. These are typically sedges, cattails, pickeral weeds, etc. which provide perches for emerging adults, and also places for adults to lay their eggs.
The pond vegetation should cover about 50-70% of the pond's surface with 5% emergent, 10-25% floating and 25-50% submerged. Plants can remain in their pots if they are in a clay soil. Place them in the desired location and add gravel to the tops of the soil to help keep them in place. The perimeter of the pond should be surrounded with marginal plants, but keep a couple of pathways open so you can enjoy the pond up-close.
It's always best to use plants that are native to your area. Your local nursery is your best source of information on this subject. For submerged plants, ask about anacharis (Egeria densa), fanwort (Cabomba canadensis), hornwort (Ceratophyllum demersum) and wild celery (Vallisneria sp.). For emergent plants, consider corkscrew rush (Juncus effusus), dwarf horsetail (Equisetum scirpoides), dwarf papyrus (Cyperus isocladus), blue flag iris (Iris versicolor) and parrot's feather (Myriophyllum aquatic).
Here are some pond plants on Amazon (these affiliate links pay us a small commission and helps us bring this free resource to the dragonfly-loving community):