Hemlocks appreciate sun, but they are also very tolerant of shade. They grow in moderately coarse sandy or gravelly soil as well as in clay or soil with silt. While well-drained soil is always desirable, Hemlocks are not fussy about that. They do insist on moist soil that is fairly acid (pH 4.6 to 6.5). Hemlocks also need protection from drying winds, especially in the Midwest.
Staking - Stake newly planted Hemlocks only if they are at risk of being blown over or uprooted before they get established. Where prevailing winds are a potential problem, stake newly planted trees for up to a year. Staked for longer periods, trees may not develop sufficient stabilizing roots on their own. Also the ties may damage them.
Drive 3 posts into the ground equidistant around the young tree out about 4 feet from the trunk. Loop soft cables of clothesline or commercial staking material around the main stem and fasten one at each stake. Allow flexibility in the lines so the stem can move a little in the wind. Check often to make sure the lines do not bind or injure the trunk in any way. After a year, or when the roots are securely anchored remove the staking.