When should I plant gladiolus bulbs outdoors?

Question:

When should I plant gladiolus bulbs outdoors?

Answer:

Gladiolus bulbs (corms) should be planted after the danger of frost is past.  In Iowa, it’s generally safe to begin planting gladioli in early to mid-May.  Make successive plantings every 2 weeks for continuous bloom from mid-summer to early fall.  Gladiolus corms bloom approximately 8 to 10 weeks after planting.  The final planting should be made in early July. 

When purchasing gladioli, select corms that are 1½ to 2 inches in diameter.  Smaller corms will not bloom as well.  Plant the corms 4 to 6 inches deep.  Gladioli perform best in well-drained soils in full sun.  Planting sites should receive at least 6 hours of direct sun per day.