May Blooms: Best Flowers to Plant This Month
Introduction
May ushers in a riot of colour and fragrance as spring reaches its peak. The soil has warmed, frost risk has passed in most regions, and daylight hours are long—creating ideal conditions for planting a wide variety of flowers. Whether you’re filling borders, containers, or cutting beds, strategic planting in May ensures lush blooms throughout summer and into autumn. In this SEO-friendly guide, we’ll explore why May is prime planting time, share essential soil and site preparation tips, and highlight the top 10 flowers to plant this month. We’ll also cover care best practices, companion planting ideas, and troubleshooting tips to keep your garden looking its best. Let’s dive in!
Why May Is Ideal for Flower Planting
- Stable Soil Temperatures: With soil consistently above 10 °C (50 °F), seeds germinate quickly and young roots establish easily.
- Extended Growing Season: Planting in May maximizes bloom time, giving annuals and tender perennials a head start.
- Reduced Frost Risk: Late frosts are rare by mid-May, so you can confidently set out tender bedding plants.
- Pollinator Activity: Bees, butterflies, and other beneficial insects are active, enhancing pollination and overall garden health.
Preparing Your Flower Beds and Containers
Soil Preparation
- Test and Amend pH
- Ideal range for most ornamentals: 6.0–7.0.
- Add garden lime or wood ash to raise pH; sulfur or peat moss to lower it.
- Enrich with Organic Matter
- Incorporate 5–10 cm (2–4 in) of well-rotted compost or aged manure into the top 20 cm (8 in) of soil.
- This improves drainage, nutrient content, and moisture-holding capacity.
- Fertilizer Boost
- Apply a balanced slow-release granular fertilizer (e.g., 10-10-10 NPK) at the manufacturer’s rate.
- For acidic-loving flowers (azaleas, rhododendrons), choose an ericaceous feed.
Site Selection and Sunlight
- Full Sun Lovers (6+ hours): Petunias, marigolds, zinnias, dahlias.
- Partial Shade Picks (3–6 hours): Impatiens, begonias, fuchsias.
- Shade Tolerants (<3 hours): Hostas, astilbes, foxgloves.
Ensure beds and containers have good drainage—raise beds or add grit/perlite to heavy clay soils.
Top 10 Flowers to Plant in May
1. Petunias (Petunia spp.)
Why Plant Now?
Fast-growing annuals that flower prolifically from late spring until first frost.
Planting Tips:
- Set out 3–4 plants per 30 cm of border edge, or 1 plant per 20 cm in containers.
- Pinch back early growth to encourage bushiness.
- Deadhead spent blooms weekly to prolong flowering.
2. Marigolds (Tagetes spp.)
Why Plant Now?
Tolerant of heat and drought, they deter nematodes and pests among vegetables.
Planting Tips:
- Space 20–30 cm apart in full sun.
- Use French marigolds (T. patula) for compact beds and African marigolds (T. erecta) for bold borders.
- Feed once a month with a high-phosphorus bloom booster.
3. Zinnias (Zinnia elegans)
Why Plant Now?
Butterfly magnet with vibrant blooms ideal for cutting gardens.
Planting Tips:
- Direct-sow seeds or transplant seedlings after last frost.
- Space 20–25 cm apart; thin to the strongest seedlings.
- Stake tall varieties or grow in sheltered spots to prevent flopping.
4. Cosmos (Cosmos bipinnatus)
Why Plant Now?
Airy foliage and daisy-like flowers sway in the breeze, perfect for wildflower or cottage-style gardens.
Planting Tips:
- Sow seeds directly outdoors, covering lightly with 0.5 cm of soil.
- Thin to 30 cm spacing once true leaves appear.
- Provide support for taller cultivars (‘Purity’, ‘Sensation’).
5. Begonias (Begonia × semperflorens)
Why Plant Now?
Shade-tolerant flowers that bloom continuously and thrive in containers or shaded borders.
Planting Tips:
- Plant tuberous begonias in humus-rich, well-drained soil after danger of frost.
- Space 25–30 cm apart; avoid waterlogging.
- Remove faded blooms to encourage new buds.
6. Salvias (Salvia spp.)
Why Plant Now?
Long-blooming perennials in shades of blue, purple, red, and white; drought-tolerant once established.
Planting Tips:
- Plant in full sun with 30–45 cm spacing.
- Stake tall varieties and prune back by one-third after initial flush to encourage a second bloom.
7. Dahlias (Dahlia spp.)
Why Plant Now?
Show-stopping tuberous perennials with diverse flower forms, from pom-pons to dinner-plate giants.
Planting Tips:
- Plant tubers with “eyes” facing upward, 10–15 cm deep and 60 cm apart.
- Hill soil around stems as they grow to support roots and encourage side shoots.
- Pinch out the top growth at 30 cm to create a bushier plant.
8. Sweet Alyssum (Lobularia maritima)
Why Plant Now?
Low-growing annual with a honeyed fragrance; excellent for edging and groundcover.
Planting Tips:
- Sow seeds thinly or transplant seedlings 15–20 cm apart.
- Thrives in both sun and partial shade.
- Self-seeds readily—deadhead if you want to control spread.
9. Foxgloves (Digitalis purpurea)
Why Plant Now?
Biennials or short-lived perennials that lend vertical drama and attract bees.
Planting Tips:
- Sow seeds on the surface of a moist, fine-textured seed mix; don’t cover.
- Transplant or thin to 30–45 cm spacing.
- Provide light shade in hot afternoon sun to prevent scorch.
10. Cosmos Sensation Mix (Cosmos spp.)
Why Plant Now?
Mixed colours (pink, white, crimson) ideal for cutting and butterfly gardens.
Planting Tips:
- Direct sow after last frost; thin to 25–30 cm apart.
- Pinch back at 15 cm to promote branching.
- Fertilize sparingly—excess nitrogen yields foliage over flowers.
Companion Planting for Vibrant Blooms
- Color Contrasts: Pair purple salvias with yellow marigolds for a striking combo.
- Height Layering: Place tall foxgloves or dahlias at the back of borders, medium zinnias in the middle, and low alyssum at the front.
- Pest Management: Marigolds deter nematodes; cosmos attract predatory insects.
- Scent Allies: Interplant sweet alyssum near vegetables to boost pollination rates.
Ongoing Care and Maintenance
Watering
- Frequency: Water newly planted flowers daily for the first week, then every 2–3 days as they establish.
- Method: Deep, less-frequent watering encourages strong root development. Water at the base to avoid wetting foliage.
Feeding
- Liquid Feeds: Apply a balanced liquid fertilizer every 2–4 weeks during active growth.
- Slow-Release Granules: Top-dress containers and beds at the start of the season for steady nutrient release.
Deadheading and Pruning
- Deadheading: Remove spent blooms on petunias, zinnias, and salvias to prolong flowering.
- Pruning Hardbacks: Cut back perennials (e.g., salvia) by one-third mid-season to encourage a second flush.
Pest and Disease Patrol
- Aphids: Spray with insecticidal soap or blast off with a strong water jet.
- Powdery Mildew: Improve air circulation and apply organic fungicide if needed.
- Slugs/Snails: Use beer traps or copper barriers around young tubers and seedlings.
Troubleshooting Common Issues
| Problem | Symptom | Solution |
|---|---|---|
| Leggy Seedlings | Long stems, few leaves | Increase light indoors; pinch back to encourage bushiness |
| Poor Flowering | Lots of foliage, few blooms | Reduce nitrogen feed; add phosphorus-rich fertilizer |
| Yellowing Leaves | Possible nutrient deficiency | Test soil pH; amend with balanced organic feed |
| Wilting After Planting | Transplant shock or root damage | Water immediately after planting; shade for 1–2 days |
| Slug Damage on Leaves | Irregular holes, slime trails | Apply slug control measures; remove hiding spots |
Conclusion
Planting flowers in May unlocks the full potential of your garden, extending bloom times and creating a tapestry of colour and fragrance through summer. By choosing the top 10 blooms—ranging from sun-loving petunias and zinnias to shade-tolerant begonias and foxgloves—you’ll craft vibrant borders, containers, and cutting beds. Combine smart soil preparation, thoughtful companion planting, and diligent care (watering, feeding, deadheading) to keep your display healthy and flourishing. With a proactive approach to pest and disease management, your May plantings will repay you with weeks of stunning blooms and a garden alive with pollinators.
Top 10 Questions & Answers
- Can I plant these flowers directly from 6-pack trays?
Yes—harden off seedlings for 7–10 days and plant at the same depth they were in the tray. - How often should I deadhead petunias?
Weekly deadheading maintains continuous flowering; pinch back leggy stems as needed. - Do dahlias need staking?
Tall varieties (over 60 cm) benefit from staking at planting time to prevent wind damage. - Are zinnias drought-tolerant?
Moderately—water deeply during dry spells, but avoid overwatering which encourages fungal issues. - Can I grow sweet alyssum in containers?
Absolutely—mix with trailing petunias or lobelia for a fragrant, cascading display. - What fertilizer is best for annual flowers?
A balanced 10-10-10 slow-release granular or a liquid bloom booster every 2–4 weeks works well. - How do I prevent powdery mildew on salvias?
Ensure good air circulation, avoid overhead watering, and remove affected foliage promptly. - When should I trim back foxgloves?
Cut flower spikes after they finish blooming to encourage side shoots and possible rebloom. - Can I sow cosmos seeds indoors first?
Yes—sow 4–6 weeks before last frost; transplant after hardening off, but direct sowing is simplest. - How do I overwinter tuberous begonias?
Lift tubers after frost, dry them, and store in peat or vermiculite at 10–12 °C until replanting in spring.