In early spring, it is important to remove any winter mulch and old foliage from your potted iris plants in Minnesota to allow for new, fresh growth. Fertilize your plants at this time by scratching an all-purpose fertilizer into the top inch or two of soil. This is also the ideal time to mulch your garden plants. The purpose of mulching is not to protect them from the cold, but to protect them from the freeze-thaw cycle that can cause damage.
When selecting a mulch, it is important to choose one that won't compact and provides good insulation. Leaves are the most common type of mulch, but hay and street straw can also be used. To ensure your iris plants are healthy, it is important to provide good drainage to prevent their roots from getting wet. When planting irises, you don't need to amend the soil.
Simply dig a trench with a garden tractor, place the iris in the trench and cover with soil. Don Scoop of Irises at Winterberry Gardens recommends using pine bark mulch on iris beds, although not too thickly. Additionally, it is important to remove old, discolored flowers from shrub roses throughout summer to improve the shape of the plant and encourage more flowers to bloom.