Plants are often selected as companions for other flowers in order to make a dramatic statement, add color and interest or hide the foliage for a flower that has a single blooming period. For irises, the choice of companion plants can be for any of these reasons. Bearded, Japanese, reticulata, xiphium, Siberian or Juno--a wide variety of irises exists to fit most gardens' needs and preferences, with bloom times throughout the year. The iris unguicularis blooms throughout the winter. Know what type of iris is in your yard before selecting companion plants.
Test the soil in the garden at least a month before planting the irises. Irises thrive in soil with a neutral pH. Mix sulfur or organic mulches in the soil with a high alkaline pH. Mix hydrated lime to raise the pH of acidic soils.
Plant companion flowers that bloom in the early spring to hide the foliage of later blooming irises. These include most spring bulbs, such as hyacinths, amaryllis or tulips.
Select companion flowers that bloom in the mid to late spring. Allium (ornamental onion), lavender, balloon flowers, daisies and Peruvian lily grow well with irises.
Plant summer blooming flowers along with irises. These include anomatheca (lapeirousia laxa) achillea (yarrow), hosta, day lilies, periwinkle (vinca minor), echinanea, marigolds and alyssum.
Select fall blooming flowers to dress up beds with spent irises. These flowers include belladonna, canna, sea lavender, lirope and fall crocus.