Basic Cypress Requirements
Cypress plants can thrive in a variety of soils--dry, sandy, loamy, boggy--but it is known for its ability to grow in wet, regularly flooded areas. In any case, a source of regular moisture is important. It can survive in nutrient-poor soil, and can also handle a wide pH range, from acidic to alkaline. However, for best results, acidic soil is preferred.
Cypress plants require a lot of sun. Full sun all day is best, though it can tolerate shade parts of the day.
Depending on the cypress plant's growth rate (some grow fast and others slow), and the purpose for which you are cultivating a cypress tree, be sure to give its roots adequate room to spread out unhampered by things buried underground, like utility lines for example.
Different Methods for Different Purposes
If you're growing these trees outside as part of informal landscaping, or to benefit riparian habitats and the local water table, most of what you really need to do is give the trees a lot of space and adequate sunlight. Most of the time the cypress will take care of itself.
If you're planting your trees for windrows or more formal landscaping, a little more pruning will be necessary to promote uniform growth.
As topiaries and indoor houseplants, the cypress takes pruning and shaping well. Set the trees in a sunny place, or move them around as needed to fulfill their sun requirements.
As bonsai, the cypress adapts well to the severe constraints put on its roots and size, tolerating well severe pruning and wiring to create the classic bonsai shapes. Bonsai do not need the kind of sun large trees require, but regular exposure and turning the plant every so often will ensure even growth and greenness.
In all cases, acidic soil is preferred, lest the trees become chlorotic and sickly. While soil can be acidified on a regular basis for plants in containers, larger trees in naturally alkaline soils will become difficult to maintain as the roots reach deeper into the ground. Thus, for large-scale ambitions, the best method would be to plant cypress in naturally acidic soils.