Iris flowers grow from bulbs rather than seeds. They produce clumps of green, leaflike foliage with a tall centre stalk that supports the colourful flower blooms. Iris bulbs are hardy enough to plant outdoors, but you can also plant them in pots that are kept indoors. When iris bulbs are grown indoors, they experience a longer blooming season because you can regulate the temperature. In addition, indoor irises will not be eaten by pests such as deer, squirrels and gophers.
Fill your desired plant pot half-full with an all-purpose potting soil.
Place the iris bulbs in a single layer on top of the soil with the pointed end of the bulbs facing upward. Leave at least 1/2 inch of space between each bulb. You can plant as many bulbs as you like, with a maximum of 20 to 30 bulbs per 14- to 20-inch pot.
Cover the iris bulbs with a 1- to 2-inch layer of soil, or just until the tips of the bulbs are no longer visible.
Water the soil until it is completely saturated and water runs out of the bottom of the pot. Place a dish under the pot to catch the excess water runoff.
Set the plant pot in an indoor location that receives bright sunlight and maintains a constant temperature of around 16.7 degrees Celsius during the day and 11.7 degrees Celsius at night. Sprouts should appear within two weeks and flower blooms will appear within 12 weeks.
Water the iris as needed; the soil will be dry and dusty.
Apply a slow-release, granular fertiliser to the soil once the iris bulbs start to bloom. Use the amount specified on the fertiliser package.
Continue your watering schedule until the iris stops blooming. When the foliage turns brown and dies back, typically in mid- to late summer, water the plant once per week until the fall. Increase your watering schedule to keep the top 1 to 2 inches of soil moist until the iris bulb produces new green shoots.