Can You Grow Northern Lights Outdoors? While Northern Lights is a good choice for indoor cultivators, it can be grown outdoors as well. It grows best in sunny climates in areas with long, warm summers. The ideal temperature for growth is about 70-85° F. Keep in mind, outdoor growing will take significantly longer periods of time than indoor. Is Northern Lights a good strain? Northern Lights is an excellent indica strain with THC content peaking at about 18%. How to best optimize light for growing Northern Lights plants? Basically, you need to shower your Northern Lights with light. During vegetation, NLs require extensive hours of light. While you are safe to go with at least 18 hours of light a day, in an ideal setting, you can opt for a full cycle of light or keep the lights on 24 hours non stop.