March Flower Planting Guide: What to Grow in the UK for Seasonal Blooms
As winter recedes and the UK’s gardens begin to stir, March offers a prime opportunity for sowing seeds and planting out young flowers that will emerge into a riot of colour in the coming weeks and months. By selecting hardy, cool-tolerant varieties—and giving half-hardy species a supportive start indoors—you can take advantage of improving daylight and milder temperatures. This guide explores what to grow in March for seasonal blooms, revealing which flowers thrive in early-spring conditions, plus actionable tips to ensure your garden flourishes throughout the warmer season.
Table of Contents
- Introduction: Why March Matters for UK Gardeners
- Soil, Light, and Temperature: Pre-Planting Prep
- Hardy Annuals to Plant in Early Spring
- Perennials and Biennials That Benefit From March Planting
- Bulbs and Tubers to Start in March
- Sowing Seeds: Indoors vs. Direct Outdoors
- Key Planting and Aftercare Strategies
- Conclusion
- Top 10 Questions and Answers
- Meta Description
1. Introduction: Why March Matters for UK Gardeners
In the UK, March typically heralds the transition from winter’s cold to spring’s mild growth spurt. Although fluctuating weather—occasional frosts or storms—remains possible, the steady increase in daylight triggers plants to awaken from dormancy. By sowing seeds and setting out transplants now, you allow flowers to develop robust root systems, ensuring they’re well-established by the time temperatures truly climb. Whether you’re a novice aiming for a simple splash of colour or an experienced gardener orchestrating a layered display, March provides an early window to create a lush, dynamic garden that bursts into life with the season.
2. Soil, Light, and Temperature: Pre-Planting Prep
Before purchasing seeds or bulbs, take a moment to evaluate the conditions of your garden:
- Soil Quality
- Drainage: Check for standing water after rain; incorporate grit or compost if necessary.
- Nutrient Levels: Boost depleted soils with well-rotted manure, compost, or balanced fertilisers.
- Sun Exposure
- Full Sun: Ideal for many blooming annuals and sun-loving perennials.
- Partial Shade: Accommodates a wide variety of woodland or shade-tolerant flowers.
- Full Shade: Focus on species specifically adapted to low-light conditions.
- Temperature Check
- Frost Risk: Keep cloches, horticultural fleece, or a cold frame handy to protect tender seedlings from unexpected chills.
- Microclimates: Walls, hedges, and raised beds can create pockets of warmth for earlier planting.
A bit of groundwork—testing soil pH, removing weeds, and outlining planting zones—ensures each seed or bulb has the best foundation for vigorous, healthy growth.
3. Hardy Annuals to Plant in Early Spring
3.1. Cornflowers (Centaurea cyanus)
- Appeal: Iconic blue blossoms that draw pollinators; perfect for cottage-garden themes.
- Method: Sow directly into prepared beds or start seedlings under cover in modules.
3.2. Calendula (Pot Marigold)
- Appeal: Bright orange and yellow daisy-like blooms; edible petals useful in salads.
- Method: Direct sow seeds or transplant young plants; thrives in sun and tolerates mild spring frosts.
3.3. Sweet Peas (Lathyrus odoratus)
- Appeal: Fragrant, colourful climbers that add vertical interest and cut-flower appeal.
- Method: Start seeds indoors in root trainers or pots; move outdoors once root systems establish.
3.4. Pansies and Violas
- Appeal: Known for their cold hardiness and cheerful early flowers.
- Method: Often available as young plugs; space them out in pots or beds, ensuring good air circulation.
3.5. Nigella (Love-in-a-Mist)
- Appeal: Lacy foliage and intriguing blooms in blues, pinks, or whites; self-seeds for naturalised drifts.
- Method: Scatter seeds lightly in sunny borders, rake gently, and keep the area moist until seedlings appear.
4. Perennials and Biennials That Benefit From March Planting
4.1. Lupins
- Trait: Tall, striking spires in diverse colours.
- Method: Plant young nursery plants or sow seeds indoors; ensure a sunny site with decent drainage.
4.2. Delphiniums
- Trait: Towering flower spikes that offer a dramatic focal point.
- Method: Sow seeds indoors or transplant established plugs; stake mature plants for support.
4.3. Foxgloves (Digitalis)
- Trait: Bell-shaped blooms that lure bees; usually biennial but can self-seed.
- Method: Scatter seeds in lightly shaded areas or transplant seedlings. Water consistently for best results.
4.4. Aquilegia (Columbine)
- Trait: Graceful, nodding flowers available in multiple hues; tolerant of partial shade.
- Method: Sow seeds or set small plants in fertile, well-drained soil. Deadhead to prevent excessive self-seeding.
5. Bulbs and Tubers to Start in March
5.1. Dahlia Tubers
- Timing: Start indoors if frosts still loom. Move outdoors once the threat passes.
- Planting: Position tubers horizontally in pots or directly in garden beds. Pinch back new growth for bushier plants.
5.2. Lily Bulbs
- Timing: Plant in March for early-to-mid summer blooms.
- Location: Sunny spot with well-draining soil to prevent bulb rot.
5.3. Begonia Tubers
- Timing: Begin indoors in trays or pots; transfer to outdoor containers later in spring.
- Condition: Prefer partial shade; keep soil moderately moist.
5.4. Gladiolus Corms
- Timing: Stagger planting from March through May for a succession of tall, showy blooms.
- Depth: Bury corms about 10 cm deep in full sun, spacing them to avoid fungal disease.
6. Sowing Seeds: Indoors vs. Direct Outdoors
Indoors/Under Cover
- Pros: Warmer temperatures speed germination; protection from unpredictable spring frosts.
- Cons: Limited space; seedlings need hardening off, which is an extra step.
Direct Sowing
- Pros: Less transplant shock; seeds adapt naturally to outdoor conditions.
- Cons: Germination may be slower in cooler soil; require careful monitoring for moisture and frost events.
Hybrid Approach: Many gardeners start half-hardy annuals and tender perennials inside while direct-sowing hardy varieties outdoors. This strategy ensures each plant thrives according to its cold tolerance.
7. Key Planting and Aftercare Strategies
- Soil Improvement
- Compost Addition: Enrich the planting site with organic matter to enhance nutrient availability.
- Grit or Sand: Enhances drainage for clay-heavy areas.
- Planting Depth
- Seeds: Follow packet guidelines; typically, smaller seeds need a light covering of soil, while larger ones can be planted more deeply.
- Bulbs and Tubers: Plant at a depth about two or three times their height.
- Watering Routine
- Initial: Thoroughly water seeds or transplants; lightly water regularly during cool, dry spells.
- Avoid Overwatering: Especially in heavy soils—soggy conditions lead to rot.
- Feeding
- Fertilizers: Balanced, slow-release products are usually sufficient for early spring. Step up feeding once plants show active growth.
- Mulch: Helps retain moisture, stabilise soil temperature, and suppress weeds.
- Pest and Disease Monitoring
- Slugs and Snails: Common in damp UK springs; deter with barriers or organic pellets.
- Aphids: Spot-treat early with insecticidal soap or companion planting (e.g., marigolds) to keep populations down.
- Hardening Off
- Process: Gradually expose indoor-grown seedlings to outdoors over 1–2 weeks. Helps them adjust to temperature swings and sunlight levels.
8. Conclusion
March can be a transformative month for UK gardens if you embrace the shifting weather and leverage it to establish hardy annuals, tender seedlings, and bulbs ready to burst into colour. By matching plant varieties to your soil type and light levels, sowing seeds thoughtfully—indoors or directly in beds—and maintaining attentive aftercare, you create an environment where each stem can flourish. As days grow longer and warmer, your efforts will culminate in a spring garden brimming with life, fragrance, and a kaleidoscope of blooming textures.
9. Top 10 Questions and Answers
- Q: Is March too early to plant in areas prone to frost?
A: Hardy annuals and bulbs often cope well. For half-hardy species, start them indoors or use cloches/fleece to protect young plants if temperatures dip. - Q: Can I plant summer bulbs like dahlias directly outside?
A: In milder regions, yes. Otherwise, start them indoors or in a greenhouse, transplanting once frosts have passed. - Q: How do I handle leggy seedlings grown indoors?
A: Provide stronger light, ensure temperatures aren’t too high, and avoid overwatering. Re-pot deeper if necessary. - Q: Should I fertilise newly planted seeds and bulbs immediately?
A: Light fertilisation can help, but many seed-starting mixes already contain nutrients. Begin regular feeding once seedlings establish. - Q: How much should I water newly sown seeds?
A: Keep the soil lightly moist but not waterlogged—excessive dampness can cause rot or fungal growth. - Q: Are there specific flowers I should avoid planting in exposed sites?
A: Delicate half-hardy annuals like cosmos or zinnias may struggle. Use windbreaks or plant hardy varieties more tolerant of strong winds. - Q: Can I reuse compost from last season for sowing seeds?
A: Refresh older compost with new organic matter or add a balanced fertiliser. Ensure it’s free from pests or diseases. - Q: Which flowers do best in partial shade this early in the year?
A: Foxgloves, aquilegias, and certain primulas thrive in dappled light or shady beds. - Q: What if I accidentally plant bulbs upside down?
A: Most bulbs will still find their way to the surface. However, it’s best to plant them at the correct orientation to avoid energy loss. - Q: How quickly will flowers bloom after a March planting?
A: Timing varies by species and weather. Hardy annuals may bloom in 2–3 months; bulbs generally flower in mid-to-late summer, depending on the variety.