Written by Sarah Jay Last updated: May 4, 2026 | 4 min read

If you want to grow summer bulbs, May is the deadline for planting them. These flower in early and late summer, and some bloom through to the fall season as well. Depending on the region you live in, these may be annual and should be removed after the foliage dies back. In more tropical regions, some can be left over the winter season to emerge again in spring. 

Make a note of whether or not you will need to remove the bulbs before frost arrives to ensure you don’t have to buy more bulbs next season. If you do have to remove them, develop a plan for storing them in the cold season. Most do well in a cardboard box filled with dry sand or peat. Some can be wrapped in newspaper and stored in a paper bag. 

The key to storage is good air flow and the right temperatures. Too warm, and the bulbs sprout, but too cold, and they could freeze. Humidity levels that are too high could promote rot, so the right range of moisture in the air is important as well. But before we get there, let’s discuss a few you can plant right now. Some are technically tubers, corms, or crowns, but are treated in the same way as true bulbs.

Millennium Gold Calla Lily Bulbs

Millennium Gold Calla Lily Bulbs

Belle of Barmera Dahlias

Abyssinian Gladiolus Bulbs

Abyssinian Gladiolus Bulbs

Millennium Gold Calla Lily

It has yellow blooms on upright stems with lightly speckled foliage.

Nothing says it’s summer like bright yellow calla lilies. Millennium Gold has three to four-inch wide blooms that emerge on upright stems amidst lightly speckled broad leaves. These are perfect for shady areas of the garden, and grow well in the ground or in containers. 

For those with no outdoor space, these are great for growing indoors as well, as temperature and humidity ranges are perfect for calla lilies. That means anyone can grow these summer bulbs. May happens to be the perfect time to get them in the garden bed or in your preferred planter.

Belle of Barmera Dahlia

A dinner-plate dahlia with pink, peach, and tangerine blooms up to 10 inches across.

The stunning pink, peach, tangerine, and canary blooms of ‘Belle of Barmera’ reach up to ten inches across at full bloom. Just like other dahlias, these are summer bulbs. May is the end of the planting season here in zone 8, but it could be the beginning for growers in zones 4 through 6. 

These dahlias are perfect cut flowers, lasting up to five days in a vase. It’s a real stunner in the garden, and looks great when planted among more minute or understated monochrome blooms. Or plant an entire garden of dinnerplate dahlias and let them pop off. 

Abyssinian Gladiolus

Fragrant white blooms have maroon centers that flower in late summer.

This 1993 award-winning flower blooms in late summer, so you can plant it with other summer bulbs. May is a great time to get these started. They’ll take off at the end of the summer season and carry the garden through to the fall season. 

The blooms of Abyssinian gladiolus (also called sword lilies) have white petals with maroon to deep red-purple middles. If you appreciate fragrant blooms, this is a great choice, as the scent is likened to gardenias. 

Orange Ton Asiatic Lily

Tall stems are topped with bright orange blooms up to eight inches across.

Bright pops of orange are exactly what you should expect when you grow ‘Orange Ton’ lily. It comes in classic form, with tall stems covered in whorled, alternate, lance-shaped leaves. The blooms open at the height of the summer, and look best when planted on their own as a statement piece or among more muted tones.

The blooms reach up to eight inches across. These are the perfect summer bulbs. May is a great time to plant yours in the ground or in your preferred planter. Keep them indoors, or let them perennialize in the garden bed. This is one of the few on this list that will require little maintenance once planted, even in colder areas. 

Central Park Oriental Poppy

Large, crinkled blooms open in late spring and continue through summer.

The lovely, crinkled blooms of ‘Central Park’ poppies are among the more delicate summer bulbs. May is actually the start of their blooming season, as they open in late spring and remain through summer, and sometimes into the fall. These blooms are big, reaching up to six inches across. 

Once these are established, they require little to no maintenance. They’re excellent cut flowers, with thin, wiry stems that stay upright. They’re deer-resistant and drought-tolerant as well, making them a great addition for bordered areas where wild animals visit. 

Something Shocking Siberian Iris

A Siberian iris suited to moist soil near ponds and streams.

This iris really does offer something shocking in its bright coloration and interesting form. Among the others on this list, this one is best for areas where the soil is sometimes wet. Plant yours along pondsides and streams, or in areas where it’s sometimes boggy. 

‘Something Shocking’ was hybridized in 2013 by Robert Hollingworth, a famous Iris breeder from Michigan. You’ll see some variation in the blooms, with some maintaining a dark purple, almost eggplant color, while others have a bright violet blue.  

Creme de la Creme Hardy Tall Phlox

A long-blooming phlox with lime-edged cream petals and a light fragrance.

Tall phlox is a pollinator magnet. The wide, semi-tubular blooms of Phlox paniculata are nectar reservoirs for hungry butterflies, bees, moths, and hummingbirds. ‘Creme de la Creme’ is a unique variety, with lime green-edged cream-colored petals with blushed centers. The density of the blooms is unmatched. 

This phlox blooms from summer through fall, and will perennialize across its hardiness range. You can expect it to return in spring and bloom again for multiple summers. The blooms are scented, making them great for arrangements as well.