Flowers that bloom in late spring are a particular joy to have in the garden, signifying the end of spring and the beginning of summer. Though many flowers produce their blooms in early spring and finish flowering by mid spring, there are a number of late spring blooming flowers that will continue flowering until well into the summer season.
Clustered bellflower (Campanula glomerata) is a lively perennial that can be grown with ease in USDA Hardiness Zones 4a to 9a. The bushy plant boasts rich green foliage and clusters of jagged purplish blue flowers, which appear in late spring and continue on until mid summer.
Grow clustered bellflower in full sunlight or partial sun, in well-drained alkaline or neutral soil. Keep the soil consistently moist. Clustered bellflower is invasive in some areas, so check a local invasive plant list before you plant it.
Wild petunia (Ruellia brittoniana), also called Mexican bluebell, is a low growing, flowering perennial native to North America that begins to produce its bluish-lilac colored flowers in late spring. The spreading plant has a naturalized appearance and works well as a ground cover plant.
Grow wild petunia in partial sunlight in USDA Zones 8a to 11a. The plant loves moist soil, and will even tolerate mild flooding. Soil should be acidic or neutral.
A member of the Iris family, Gladiolus (Gladiolus spp.) is a tender perennial that boasts stiff, tall stalks topped with floppy blooms in a variety of colors. Cultivars and hybrids of the Grandiflorus group produce their striking blooms in late spring, often continuing on all the way into fall. Gladiolus grow best in full sunlight in USDA Zones 7 to 10. The plant prefers soil that is fertile and well drained. Water Gladiolus on a regular basis: more in the summer, less in colder months.