Black plastic mulch has long been a popular mulch in cooler climates where gardeners find it hard to keep soil warm enough for heat-loving plants such as tomatoes, peppers, and melons. While black plastic mulch can certainly get the job done when applied correctly, gardeners also have other options, such as clear plastic mulch and various colored mulches. Clear plastic mulch actually transmits more of the sun's heat to the soil below than black plastic, but also promotes weed growth. Hence, if the choice is between black and clear plastic mulch, and black plastic mulch provides enough heat retention to get the job done, then it is a better choice. However, if more heat is necessary and you are willing to deal with the accompanying weeds, you may want to opt for clear plastic mulch.
Other options include Infra-Red Transmitting (IRT) mulches, which have the heat power of clear mulches and the weed-fighting power of black mulches, but typically come at a higher price when they can be found. Variously colored mulches can promote more bountiful growth when coupled with the right plants in the right climates. For example, some studies have shown that in the northern United States, muskmelons, summer squashes, and cucumbers seem to prefer bark blue mulches while tomatoes, potatoes, and eggplants often prefer red mulches. If sorting through these options is more work than you are interested in doing, then don't worry: black plastic mulch is probably all you really need.