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Bulbs are a gardener’s shortcut to instant color. If you want a summer garden bursting with lilies, irises, gladiolus, and more, May is the ideal planting window.
Written by Sarah Jay
Last updated: May 4, 2026 | 4 min read
Planting summer bulbs in May gives you a head start on a garden that will flourish from early to late summer, and in some regions even carry over into fall. Depending on your climate, you may need to remove the bulbs after the foliage dies back, or you can leave them in place over the winter in warmer areas.
Before you dig, decide whether the bulbs will need to be removed before frost. If so, plan for proper storage: a cardboard box filled with dry sand or peat works well, or you can wrap them in newspaper and keep them in a paper bag. The key is good airflow, the right temperature (neither too warm nor too cold), and moderate humidity to prevent rot.
Below are seven summer bulbs that are perfect for planting in May. Some are technically tubers, corms, or crowns, but they’re handled the same way as true bulbs.
With bright yellow, cup‑shaped blooms on upright stems, the Millennium Gold Calla Lily (Zantedeschia ‘Millennium Gold’) brings a cheerful summer vibe. The flowers measure 3–4 inches across and sit atop lightly speckled, broad leaves. They thrive in full sun to partial shade and reach 18–24 inches tall. Hardy in zones 7–10, they’re suitable for both garden beds and containers, and can even be grown indoors with the right temperature and humidity.
The Belle of Barmera Dahlia (Dahlia ‘Belle of Barmera’) showcases a dinner‑plate of pink, peach, tangerine, and canary blooms up to 10 inches across. Requiring full sun, it grows 4–5 feet tall and is hardy in zones 8–11. Although May marks the end of the planting season in zone 8, it can still be planted in zones 4–6. This dahlia is an excellent cut flower, lasting up to five days in a vase, and adds a dramatic focal point when planted among more subdued blossoms.
Known for its fragrant white petals with maroon to deep red‑purple centers, the Abyssinian Gladiolus (Gladiolus callianthus murielae) blooms late in summer and can carry the garden into fall. It grows 2–3 feet tall, prefers full sun, and is hardy in zones 7–10. The scent, often likened to gardenias, makes it a standout choice for those who appreciate aromatic flowers.
The Orange Ton Asiatic Lily (Lilium ‘Orange Ton’) offers bold, bright orange blooms up to eight inches across on tall stems that reach 36–40 inches. It thrives in full sun to partial shade and is hardy in zones 3–8. Once planted, this lily requires minimal maintenance and can be left in the ground to become a perennial staple in cooler climates.
Central Park Oriental Poppy (Papaver orientale ‘Central Park’) delivers large, crinkled blooms that open in late spring and continue through summer, sometimes into fall. With flowers up to six inches across, it reaches 30 inches tall and is hardy in zones 3–7. This poppy needs little upkeep once established, is deer‑resistant, and drought‑tolerant, making it ideal for borders that attract wildlife.
The Something Shocking Siberian Iris (Iris ‘Something Shocking’) is designed for moist soils near ponds and streams. Hybridized in 2013 by renowned iris breeder Robert Hollingworth, it offers vibrant hues ranging from dark purple to bright violet‑blue. Growing 32 inches tall, it prefers full sun to partial shade and is hardy in zones 3–8.
Creme de la Creme Hardy Tall Phlox (Phlox paniculata ‘Creme de la Creme’) is a pollinator magnet, with lime‑edged cream petals and a subtle fragrance. Growing 2–3 feet tall, it thrives in full sun to partial shade and is hardy across zones 3–9. This phlox blooms from summer through fall, returning each spring for multiple seasons, and its dense, scented blooms make it a favorite for both gardens and arrangements.
