Blue Dutch iris is a long-stemmed, medium-sized perennial iris that blooms in the late spring or early summer. Their bright blue petals and golden yellow throats perched atop thin, graceful stems make them a favourite of florists and home gardeners alike. Dutch iris are particularly suited for growing in containers because, once planted, they require minimal care. They thrive in areas with subzero winters as long as they are protected, but don't fare as well in hot, tropical regions. Plant in the late fall after temperatures have cooled for best results.
Fill the container with a good-quality organic commercial potting mix. Water thoroughly and allow to drain. Check to make sure the container drains well, as iris are prone to rot in waterlogged soil. Place the container on its dripping pan.
Set the container in a location where it receives full sun. Avoid any location where the container could cause water damage if it overflows.
Dig one hole for each iris bulb. Dig the holes 2 inches deep and 3-4 inches apart. Dig five holes for an 8-inch pot, seven holes for a 10-inch pot and nine holes for a 12 to15-inch pot. Plant one bulb in each of the holes, taking care to set the bulb with the wide end down and the pointed end facing upward. Backfill with soil to cover the bulbs.
Water thoroughly, soaking the container. Allow to drain, and empty the dripping pan if full. Leaves will begin to sprout in the fall in warm regions, grow throughout the winter and bloom in the spring. In colder climates, foliage and flowers won't grow during the winter, but still develop in the spring. Water the plants throughout the blooming cycle. Cut the blooms at any time for flower arrangements.
Allow the foliage to stay in place after the flowering season is over. Do not remove the leaves, as the plant needs them to continue gathering sunlight and nutrients for the next year's growing season.
Remove the leaves when they yellow and die back to the base of the bulb. When the leaves have died back the plant will go dormant. Do not water the bulbs during this dormant season. The bulbs will rest for a few months and then begin a new growing cycle.
Tuck smaller bedding plants around the base of the bulbs when they begin to sprout. Iris have long, thin stems, and the shorter plants create a fuller look for the container and also provide a colour contrast. Apply a 2-inch layer of mulch over the bulbs if grown in areas where the temperature falls below -17.8 degrees C.