If your garden feels like it is missing a spark, the solution might already be waiting in a simple paper bag. This window of opportunity lasts from early summer straight through the first hints of fall. Whether you are a seasoned gardener or just starting out, understanding which bulbs to tuck into the soil this month makes all the difference.
Why May Is the Make-or-Break Month for Summer Bulbs
May acts as a critical bridge between the cool spring weather and the heat of summer. For many summer-blooming species, this is the final call. If you wait until June, you risk missing their peak flowering window or stunting their root development before the temperatures soar.
These plants flower in early and late summer, with some blooming through to the fall season as well. Depending on the region you live in, they may behave as annuals 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 you will need to remove the bulbs before frost arrives to ensure you do not 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 prematurely. Too cold, and they could freeze. Humidity levels that are too high could promote rot, so a cool, dry, dark space is ideal for overwintering your investment.
7 Stunning Summer Bulbs to Plant This May
Some of the plants on this list are technically tubers, corms, or crowns, but they are treated in the same way as true bulbs. Here are seven gorgeous options that will reward you with months of color.
1. Millennium Gold Calla Lily
Nothing says summer like bright yellow calla lilies. The Millennium Gold variety offers three to four-inch wide blooms that emerge on upright stems amidst lightly speckled broad leaves. Its botanical name is Zantedeschia ‘Millennium Gold’.
These are perfect for shady areas of the garden, and they grow well in the ground or in containers. For those with no outdoor space, these are great for growing indoors as well, as standard household temperature and humidity ranges are perfect for calla lilies. That means anyone can grow these summer bulbs to plant. May happens to be the perfect time to get them in the garden bed or in your preferred planter. They reach about 18 to 24 inches tall and thrive in full sun to partial shade, making them incredibly versatile for hardiness zones 7 through 10.
2. Abyssinian Gladiolus
Fragrant white blooms with maroon centers make this 1993 award-winning flower a standout in any late-summer garden. The Abyssinian Gladiolus, or Gladiolus callianthus murielae, blooms in late summer, so you can plant it alongside other summer bulbs for a staggered display.
May is a great time to get these started. They will take off at the end of the summer season and carry the garden through to the fall. The blooms have white petals with maroon to deep red-purple middles. If you appreciate fragrant blooms, this is a great choice, as the scent is often compared to gardenias. Plant them in full sun for the best results, and expect them to reach 2 to 3 feet in height. They are hardy in zones 7 through 10.
3. Orange Ton Asiatic Lily
Bright pops of orange are exactly what you should expect when you grow Orange Ton lily. It comes in a classic lily form, with tall stems covered in whorled, alternate, lance-shaped leaves. The blooms open at the height of 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, creating an undeniable focal point. 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. It is hardy in zones 3 through 8 and reaches 36 to 40 inches tall. Give it full sun to partial shade for the best flowering performance.
4. Central Park Oriental Poppy
The lovely, crinkled blooms of Central Park poppies are among the more delicate summer bulbs you can plant. Their botanical name is Papaver orientale ‘Central Park’. May is actually the start of their blooming season, as they open in late spring and remain through summer.
You may also enjoy reading: 9 Flower Seeds to Plant in May for Summer Blooms.
These blooms are big, reaching up to six inches across, with thin, wiry stems that make them excellent as cut flowers. Once these plants are established, they require little to no maintenance. They are deer-resistant and drought-tolerant, making them a fantastic choice for low-maintenance landscapes. They reach about 30 inches tall and are hardy in zones 3 through 7. Plant them in full sun to partial shade for the best results.
5. Something Shocking Siberian Iris
This iris really does offer something shocking in its bright coloration and interesting form. Among the other bulbs on this list, it stands out for its specific soil preferences. Plant yours along pondsides and streams, or in areas where it is sometimes boggy. It is the perfect solution for that tricky spot in your yard where water tends to collect.
Something Shocking was hybridized in 2013 by Robert Hollingworth. You will see blooms that show variation, with some maintaining dark purple hues that catch the light beautifully. It reaches 32 inches tall and is hardy in zones 3 through 8. It thrives in full sun to partial shade.
6. Belle of Barmera Dahlia
If you want a showstopping display that lasts from midsummer until the first frost, dahlias are the undeniable champions. The Belle of Barmera variety produces masses of pink and yellow blooms that can reach up to 6 inches across. The more you cut them, the more they bloom, making them a gift that keeps on giving.
Although technically a tuber, it is treated exactly like a true bulb for planting purposes. Plant the tubers in May after the last frost has passed. They need warm soil to sprout. They reach about 3 to 4 feet tall and thrive in full sun. In zones 8 through 11, they can be left in the ground. In colder zones, dig them up in the fall and store them in a cool, dry place.
7. Tropicanna Canna Lily
For a bold, tropical statement, nothing beats the vibrant foliage and flowers of the Canna Lily. The Tropicanna variety is grown as much for its stunning striped foliage, which features shades of green, yellow, pink, and red, as for its bright orange flowers. The leaves alone are enough to make it the centerpiece of your garden.
Plant the rhizomes in May in rich, well-draining soil. They are heavy feeders and love consistent moisture. They bring a slice of the tropics to any garden bed or large container. They reach 4 to 5 feet tall and are hardy in zones 7 through 10. Give them full sun for the most vibrant foliage and the largest blooms.
Getting these seven varieties into the soil this May will set the stage for a spectacular summer display. Whether you have a sprawling garden, a small urban patio, or just a sunny windowsill, there is a bulb on this list that will thrive. Just remember to check your hardiness zone and have a plan for overwintering if needed. Happy planting.
