The space per cannabis plant depends on how big you want your plants to be and how much yield you want to get. Generally, you can use the rule of thumb of 1 plant per sq ft, but you can also adjust this according to your preferences. For example, if you want your plants to grow bigger with more buds, you can give them more space, such as 2 or 3 sq ft per plant. If you want smaller plants with less maintenance, you can give them less space, such as 0.5 or 0.75 sq ft per plant.