As the ground thaws and the first signs of spring emerge, March serves as a critical pivot point for gardeners looking to secure a vibrant summer display. This month offers a unique dual opportunity: while it is the prime window for planting summer-flowering bulbs like dahlias and gladioli, it also provides a “second chance” for those who missed the autumn window for spring mainstays like snowdrops and bluebells.
Effective March gardening requires a strategic approach to both indoor cultivation and outdoor soil preparation. By starting tender species under glass and placing hardy varieties directly into the earth, enthusiasts can ensure a continuous succession of blooms from early summer through the first frosts of autumn.
The Summer Stars: Planting for Seasonal Impact
Unlike spring-blooming bulbs that require a winter chill, summer-flowering varieties thrive on warmth. Leading the charge are Dahlias, prized for their architectural presence. In milder coastal or southern regions, tubers can be transitioned into the ground by mid-March. However, experts recommend waiting until late April in cooler climates. To ensure success, plant tubers 10–15 cm deep in nutrient-rich, well-drained soil. Because dahlias can reach significant heights, it is advisable to place support stakes at the time of planting to avoid piercing the tubers later in the season.
For those seeking vertical interest, Gladioli are indispensable. To avoid a finished bloom cycle all at once, gardeners should practice “succession planting,” putting corms into the ground every two weeks from March through May. This technique guarantees a fresh supply of floral spikes for cutting throughout the summer.
Other notable additions for outdoor planting include:
- Crocosmia: Known for fiery hues, these should be planted in clumps to maximize visual impact.
- Eucomis (Pineapple Lily): An exotic, late-summer bloomer that excels in sunny, sheltered borders.
Maximizing the Season: Starting Indoors
To extend the flowering window, certain “hungry” bulbs benefit from an indoor head start. Cannas and Tuberous Begonias are particularly sensitive to frost and should be started in pots during March. Begonias should be placed hollow-side up in moist compost at temperatures between 18°C and 21°C. Likewise, Cannas—which bring a tropical flair to temperate gardens—should be soaked in warm water for 24 hours prior to potting to break their dormancy.
Once the threat of frost has passed in late May, these established plants can be “hardened off” by gradual exposure to outdoor temperatures before being permanently transplanted.
The “In the Green” Loophole
A common misconception is that missing the October planting window means a year without spring classics. However, March is the peak time to purchase bulbs “in the green.” This refers to plants like snowdrops and bluebells that are lifted and sold while actively growing rather than dormant. This method is often more successful for establishing snowdrop colonies, as the plants transplant more reliably when their root systems are active.
Professional Maintenance and Protection
Success in bulb gardening is often a matter of drainage and nutrition. Most bulbs are prone to rot in waterlogged conditions; if working with heavy clay, growers should incorporate horticultural grit or organic compost to improve soil structure.
Regarding nutrition, once foliage is established, a high-potassium liquid feed—similar to tomato fertilizer—should be applied fortnightly. This directs the plant’s energy toward flower production rather than excessive leaf growth.
Finally, gardeners must remain vigilant against late-season cold snaps. Keeping horticultural fleece nearby to cover emerging shoots during overnight frosts can mean the difference between a record-breaking bloom and a lost season. Monitoring for early-season pests, particularly slugs and vine weevils, will ensure that young, vulnerable growth survives to reach its full potential.