Position: Full sun, just make sure the pot is not getting too hot during the summer months. A hardy species, but still some protection from extreme frost is a good practice for potted specimens with delicate root system.
Watering: Water abundantly and frequently during the whole year. It can withstand very soggy soil for prolonged period, similarly to Taxodium.
Feeding: It is a very vigourous species, so high nitrogen fertilisation should be limited to spring for mature specimen to avoid excessive growth and internode length.
Repotting: Repot in late winter to early spring, relatively frequently as roots are fast growing and can rapidly fill the pot and obstruct water drainage. Roots can be pruned quite aggressively despite it being a conifer.
Soil Ph: Very tolerant of highly acidic soils
Pruning: Prune frequently during the growing season. It can often bud back from old scars and in existing branches axils. Make sure you remove all unwanted shoots as soon as they appear to avoid scars and inverse taper.
Wiring: Wiring green twigs is almost impossible as they are extremely brittle. Wait for lignification to start to bend flexible branches with Aluminum wire, or use guy wires for older branches/trunk.
Pests and Disease: No particular disease are known to easily affect Dawn Redwood. Spider mite can be a problem in particularly dry environment. Fungal infection can sometimes create problems when humidity and temperature are persistently very high.