Summer Flowering Bulbs to Grow

Flower Bulbs to Keep Color in the Garden All Summer

Growing Dahlias
Dahlias add late season color to the garden. Photo: © Marie Iannotti

We often think of planting bulbs for spring color, but there are many summer flowering bulbs, corms, rhizomes and tubers that add color and a touch of the tropics to the peak season garden. In warmer climates, many of these flowering bulbs can be left in the ground all year and some will even naturalize. Gardeners in cooler climates can still enjoy summer blooming bulbs, either by growing them as annuals or by digging them in the fall, storing them for the winter and replanting when the weather warms in the spring.

Here are some summer blooming bulbs, corms, rhizomes and tubers worth adding to your garden:

  • Agapanthus orientalis (Lily of the Nile) Bright blue or white flowers bloom in mid-summer along tall stalks that can reach 4-5 feet. Where hardy, to Zone 9, Agapanthus can remain evergreen throughout the winter. In colder zones, the bulbs will need to be dug and stored. Agapanthus is very drought resistant and prefers full sun to partial shade.
  • Begonia tuberhybrida (Tuberous Begonias) The saturated intensity of color offered by tuberous begonias will quickly light up a shady corner. The foliage looks almost succulent. The long blooming flowers make tuberous begonias a great choice for containers. Hardy only to Zone 9, the tubers will need to be dug and stored for the winter elsewhere.
  • Caladium (Caladium horulanum) Caladiums are grown for their large, colorful leaves. Splashed or swirled with greens, whites, reds and pink, caladiums add a touch of the tropics to a shade garden. Most gardeners grow them as annuals. They are hardy to Zone 10 and can be dug and stored or even brought inside as a house plant.
  • Canna (Canna) Cannas have really come into their own recently, with the introduction of so many exotic and colorful varieties. Tall and showy, there’s no mistaking their tropical appeal. Cooler than Zone 8, cannas will need to be dug and stored. Warmer than Zone 8, you may even be able to naturalize your cannas.
  • Convallaria majalis (Lily-of-the-Valley) You almost have to look for lily-of-the-valley to actually see the flowers, but the intense scent will guide you where to look. These dainty plants are hardy down to Zone 4 and will naturalize and form a carpet in colder zones, especially in slightly acid soil.
  • Dahlia (Dahlia) This is a huge family of very diverse flowers, popular for competitions. The smaller varieties are often grown as annual bedding plants, but dahlias are hardy to Zone 9 and the tubers can be dug and stored elsewhere.
  • Gladiolus (Gladiolus) It would be hard to find more popular cut flower. The trumpet shaped flowers on long stalks are a sure sign it’s summer. The tall types are only hardy to Zone 9, but there are smaller varieties, G. colvillei, that are hardier and the corms don’t require digging and storage.
  • Iris (Iris) There’s an iris to please every gardener. The tall bearded iris are traditional favorites. There are also the delicate Siberian iris, the dainty iris cristata and the water loving flag iris. Most are pretty much self-sufficient and hardy to Zone 5. Some varieties are even hardier.
  • Lilium (Lily) Lilium is a large and diverse group of trumpet shaped flowers. You can find almost every color and heights from about 2 feet to over 6. Most are hardy to down to Zone 4 and will require little care, once established.
  • Zantedeschia (Calla Lily) Another tropical looking summer bloomer that is hardy to Zone 8. The cup shaped summer blooming flowers are typically white, but also come in yellow, pink and red. They are generally grown as annuals in cooler climates.