If you are someone who gets a sense of satisfaction from undertaking your own projects, then you can create your own fertilizer for plants such as bearded iris. Although iris plants don't need fertilizer to thrive, they will produce a better showing of flowers if you can give them the correct amount of fertilizer at the correct time. Irises need nitrogen, potassium and phosphorus to thrive. But too much nitrogen can cause plants to put out more vegetation than flowers.
Combine powdered fish fertilizer, seaweed, Epsom salts, molasses and water in a bucket. Fish fertilizer contains all nutrients that the flowers need. Seaweed provides extra potassium for flower blooms, and molasses provides sugar for food along with iron and minerals.
Stir with a stirring stick until well mixed.
Pour mixture into watering can.
Wait until evening to water irises. Nutrient mixes poured over plants in the heat of the day may burn plants.
Water irises until the ground is saturated. Two quarts of fertilizer will water a bed of irises that is 3 feet wide by 6 feet long.
Fertilize irises just before blooming and again midway through the blooming cycle. Discontinue after blooming.