As the spring equinox approaches, the horticultural world is shifting its focus toward the future. March represents a critical window for garden enthusiasts, serving as the bridge between the fading beauty of winter and the anticipated vibrancy of the summer landscape. While autumn is traditionally the season for planting spring-flowering staples like tulips and daffodils, experts note that the current weeks are the prime time for establishing summer-flowering bulbs, tubers, and corms.
Navigating the “Spring Bulb” Paradox
For those who missed the autumn planting window, the gardening season is far from lost. Professional growers distinguish between two categories of bulbs available in March. While spring-flowering varieties are best planted in the fall, “in the green” specimens—plants lifted while actively growing—are currently available at garden centers. These allow gardeners to establish snowdrops and bluebells immediately.
However, the primary focus this month is on summer-flowering varieties such as dahlias, gladioli, and lilies. These heat-loving plants require a spring start to ensure a prolific display from July through the first frosts of autumn.
Strategies for Outdoor Establishment
Several hardy and semi-hardy species can be integrated directly into the landscape as soil temperatures rise.
- Dahlias: These versatile tubers should be planted 10–15 cm deep in nutrient-rich, well-drained soil. Because they are susceptible to late frosts, gardeners in cooler climates are advised to wait until late April or keep protective horticultural fleece on standby.
- Gladioli: To bypass a singular, short-lived bloom, experts recommend “succession planting.” By burying corms 10 cm deep every two weeks from March through May, gardeners can ensure a continuous harvest of architectural flower spikes for indoor arrangements.
- Crocosmia and Eucomis: For those seeking exotic flair, the Pineapple Lily (Eucomis) and the bee-friendly Crocosmia ‘Lucifer’ offer striking textures. These should be planted in sun-drenched, sheltered spots to mimic their native climates.
Maximizing the Season with Indoor Starting
In regions where the ground remains cold or damp, starting tender bulbs indoors can provide a significant head start. Tuberous begonias, which thrive in shaded areas where other bulbs falter, should be started in shallow trays with the hollow side facing upward. Similarly, Canna rhizomes benefit from a 24-hour soak in warm water before being potted and kept at temperatures above 18°C. This controlled environment fosters strong root systems, leading to earlier flowering once moved outdoors in late May.
Maintenance and Pest Mitigation
The success of a summer garden depends largely on soil preparation and vigilance. Heavy clay soils should be amended with grit and organic compost to prevent bulb rot. A general rule for planting depth is to bury the bulb at two to three times its own diameter.
As growth emerges, the primary threat transitions from weather to pests. Slugs and snails frequently target tender new shoots; gardeners are encouraged to use biological controls like nematodes or copper barriers to protect their investment. Furthermore, as foliage develops, switching to a high-potassium liquid fertilizer, such as tomato feed, will prioritize flower production over excess leaf growth.
By taking advantage of the March planting window, gardeners transform the dormant earth into a resilient, high-performance landscape. Whether opting for the dark foliage of ‘Bishop of Llandaff’ dahlias or the ruffled petals of ‘Non Stop’ begonias, the work begun this month sets the stage for a spectacular seasonal display.