Place directly in a well-lit window or near near bright natural light source. Be sure to turn the plant’s pot once in a while as to ensure that each side of the plant gets access to sunlight. This can also ensure that your cactus continues to grow vertically.
During the hotter seasons such as spring and summer, water cacti about every 3 to 4 weeks. During cold seasons, water once a month, or when the top inch of the soil is completely dry. Remember that cacti are drought-resistant plants, and survive by storing water and nutrients in their bodies. During the cold seasons such as fall and winter, cacti are dormant, and require little to no water.
During a cacti’s growing period, which usually happens during the spring and summer, you can feed cacti fertilizer about once every three weeks for extra nutrients.