Starting cacti indoors from seeds can effectively create a beautiful indoor succulent garden. While most cacti plants grow slowly, they will thrive and grow when you provide the proper environment for them. Give cacti plenty of light and minimal water to recreate a desert environment in your home. Instead of growing cactus from seedlings, try starting cactus seeds under growing lights instead. Within weeks, you may see tiny cactus seedlings emerging from the potting soil.
Fill the planting containers to the top with potting soil.
Place one cactus seed every 2 inches on the top of the potting soil and cover each seed with about 1/16 inch of soil. Spray the soil surface lightly with water from the spray bottle just to moisten the soil.
Set the planting containers in the baking pan and add approximately 1/2 inch of water to the bottom of the baking pan. Cover the baking pan with the lid.
Place the baking pan 12 inches beneath the grow lights. Keep the grow lights on between 12 and 18 hours each day.
Check the soil every day by lifting the lid of the baking pan. If you find condensation on the top of the lid, wipe it off. Refill the water level in the baking pan if it falls under 1/16 inch of water.
Remove the baking pan lid after the seeds germinate. Add gravel over the soil to keep the soil at the proper moisture level. Stretch a piece of muslin over the top of the pan and hold the muslin in place around the top edge of the pan with a length of twine. Keep the grow lights on for the same number of hours each day, and keep the water level over 1/16 inch in the pan.
Remove the muslin from the top of the baking dish for one to two hours each day when you see spines forming on the cacti. Stop watering the cacti seedlings from the bottom and begin watering the soil from the top without getting the seedlings wet in the watering process. Water the seedlings once or twice each week.