Plant growth is based on a lot of factors that aren’t necessarily correlated to being inside or outside. Plants have a few specific requirements to grow. They need water, nutrients, light, and carbon dioxide. Water can be supplied by a human to a plant regardless of whether it is kept inside or outside but being outside since water isn’t a resource that is difficult to come by. The same goes for nutrients. Plants get their nutrients though the soil they are planted in, so if a farmer prepares by planting with enough fertilizer, then the plant should be fine whether it is inside or outside. A problem arises when you consider how large the plant will grow. The larger the plant, the more room it will need to grow, and the more soil/fertilizer it will require. Unless you are willing to set aside a large area of your home, then larger plants would be better suited to grow outside. Since plants need sunlight to grow it would seem best to keep them outside, but if you are willing to purchase specialized light bulbs that mimic the sun then you could grow the plant indoors. Also, you could keep the plant by a window, but be warned: the sun may not enter through the window throughout the entire day. Lastly, plants need carbon dioxide, a gas from the air, in order to grow. While carbon dioxide is present everywhere, it is actually more concentrated inside homes than it is outside. This is because humans produce carbon dioxide by breathing so a lot of it gets trapped indoors. In conclusion, with enough time and energy spent into the set-up you could grow plants faster indoors than outdoors. Take a look at greenhouses, they are specially created indoor environments meant to grow plants faster. This question is really interesting because even though it is possible to grow plants more quickly inside, it requires a lot of preparation in advance in order to achieve the desired outcome.