Cannabis clones are small and sensitive plants.
Taking extra care for your clones is crucial, as the plant's "childhood" strongly affects both the size and quality of the marijuana harvest.
The conditions that you have to ensure for succesful cloning are quite different from those that will make your mature plants thrive.
Since the amount of light that clones require is significantly smaller from what you will need at the later stage, many growers choose to keep clones under separate lighting.
For small spaces, fluorescent tube light bulbs or low power CFLs might be useful.
Most professional growers, however, will opt for the Metal Halide (MH) lamps, as they guarantee the best results.
The only drawback, especially for home growers is that they only come in 150W+ sizes.