Sweet pea flower (Lathyrus odoratus) are beloved for their delicate beauty, sweet fragrance, and wide range of vibrant colors. These charming climbing annuals have graced English cottage gardens for centuries, symbolizing blissful pleasure and romantic nostalgia.
Known for their fluttery petals and intoxicating scent, sweet peas are a favorite among gardeners who appreciate both aesthetic appeal and aromatic delight. Whether grown on trellises, fences, or in containers, they add vertical interest and old-fashioned charm to any garden space.
What makes sweet peas even more popular is how rewarding they are to grow—from the moment their seeds germinate to the time they burst into fragrant bloom. Gardeners of all skill levels enjoy nurturing them, as they offer both visual satisfaction and the joy of fresh-cut bouquets.
In this guide, you’ll learn everything you need to know about:
- Planting sweet peas the right way
- Growing them into strong, flourishing vines
- Caring for their specific needs
- Maintaining healthy plants throughout the season
Sweet Pea Flower Overview
- Name: Sweet Pea
- Family: Fabaceae (Legume family)
- Mature Size: 3–6 feet tall, 1–2 feet wide (climbing varieties; bush types are smaller)
- Plant Type: Annual (some species are perennial, but Lathyrus odoratus is annual)
- Botanical Name: Lathyrus odoratus
- Sun Exposure: Full sun (at least 6 hours daily)
- Soil Type: Well-drained, rich in organic matter; neutral to slightly alkaline pH
- Bloom Time: Late spring to early summer (longer in cool climates)
- Flower Color: Pink, purple, white, red, blue, and bicolors
- Hardiness Zones: USDA zones 2–11 (grown as an annual)
- Native Area: Eastern Mediterranean (Italy, Sicily, Cyprus)
- Toxicity: Toxic to pets and humans if seeds or large quantities of plant material are ingested
Topics Related To Plants:
How to Plant Sweet Pea Flowers
Planting sweet peas at the right time and in the right conditions sets the foundation for a healthy, vibrant display of blooms. These cool-season flowering plants thrive when sown early, allowing them to establish strong roots before the heat of summer.
When to Plant Sweet Peas
Sweet peas prefer cooler weather, making early spring or late winter the best time to plant sweet peas. In mild climates, you can sow seeds in the fall for earlier spring blooms. In colder areas, wait until the soil is workable but still cool—typically a few weeks before the last expected frost.
Choosing the Right Location
Select a sunny location with well-drained soil. Sweet peas need at least 6 hours of direct sunlight daily to thrive and produce abundant blooms. Avoid overly wet areas, as soggy roots can lead to rot.
Preparing the Soil
Sweet peas grow best in soil that is:
- Rich in organic matter (compost or aged manure works well)
- Slightly alkaline to neutral pH (6.5–7.5)
- Well-aerated with good drainage
Adding a balanced organic fertilizer at planting time supports early growth, but avoid high-nitrogen feeds, as they encourage leafiness over blooms.
Sweet Pea Seed Germination Tips
To improve sweet pea seed germination, soak seeds for 6–12 hours before planting. This softens their hard outer shell and helps them sprout faster. Some gardeners gently nick the seed coat with a nail file, but soaking is often sufficient.
How to Sow Seeds
- Plant seeds about 1 inch deep and 2–3 inches apart
- If growing in rows, leave about 12 inches between rows
- Cover lightly with soil and water gently but thoroughly
Direct Sowing vs Starting Indoors
Direct sowing is ideal in climates with a long cool season. In short-season or colder regions, start seeds indoors in biodegradable pots 4–6 weeks before transplanting. This avoids disturbing their roots when moving them outdoors.
Labeling & Varieties
Sweet pea varieties can vary in height, bloom size, and fragrance. Use seed packets to guide planting and care instructions, and label different varieties clearly in your garden so you can track performance and color mix.
Tips for Growing Sweet Peas Successfully
Sweet peas are elegant fragrant climbing flowers that reward gardeners with vibrant color and irresistible scent. While they’re relatively easy to grow, giving them the right structure, space, and conditions will help you get the most out of your plants.
Support Structures: Trellises and More
Sweet peas, especially tall and vining types, need something to climb. Use a garden trellis, netting, bamboo canes, or a decorative obelisk to give the vines support. Install your support early—preferably at planting time—so the seedlings can latch on as they grow. Without support, they’ll flop and tangle, which reduces airflow and bloom quality.
Companion Plants and Spacing
Sweet peas grow well alongside other cool-season flowers like snapdragons, pansies, calendula, and violas. Avoid overcrowding—allow about 6 inches between plants to ensure proper airflow and reduce the risk of mildew. When planted with lower-growing companions, sweet peas will shine as vertical accents in the garden.
Ideal Climate and Temperature
Sweet peas prefer cool, mild climates. They thrive in temperatures between 50–70°F (10–21°C). Hot, dry weather can stress the plants and shorten the blooming season. In warmer regions, plant early and provide afternoon shade if possible.
Growth Stages to Expect
- Seedling stage: Emerges 7–14 days after sowing
- Vining stage: Vines begin to elongate, seeking support
- Bud formation: As days lengthen and plants mature, buds begin to appear
- Blooming: Fragrant flowers open, attracting pollinators and pleasing your senses
Regular feeding, watering, and deadheading during this phase can extend blooming time and overall plant vigor.
Annual vs Perennial Sweet Peas
Most sweet peas grown in gardens are annuals (Lathyrus odoratus), which means they complete their life cycle in one season and are prized for their scent. Perennial sweet peas (Lathyrus latifolius) return year after year but typically lack fragrance. While both produce attractive blooms, annual varieties are preferred for cut flowers and strong perfume.
Topics Related To Planting flowers:
Caring for Your Sweet Pea Plants
Once your sweet peas are up and growing, a little attention goes a long way in keeping them healthy and flower-filled. Proper watering, feeding, and maintenance are essential to extend their blooming period and keep pests and diseases at bay.
Watering Schedule and Moisture Needs
Sweet peas prefer consistently moist but not soggy soil. Aim to water deeply about 1–2 times per week, depending on your climate and rainfall. During hot or dry periods, increase the frequency slightly. Mulching around the base helps retain moisture and keep roots cool.
Avoid overhead watering, especially in humid climates, as it can contribute to fungal problems.
Fertilizing Sweet Peas
Use a balanced organic fertilizer (such as 5-5-5) once seedlings are a few inches tall. Apply every 3–4 weeks throughout the growing season. Avoid high-nitrogen fertilizers, which promote lush foliage but reduce flowering.
Adding compost at planting time can also provide a slow-release nutrient boost throughout the season.
Deadheading for Continuous Blooms
Deadheading sweet peas—removing spent flowers regularly—encourages the plant to keep producing new blooms. If you allow pods to form, the plant will shift energy toward seed production and flowering will slow or stop. Harvest flowers frequently for bouquets to promote longer bloom time.
Pro tip: Pick flowers in the morning when they’re most hydrated for the longest vase life.
Common Pests and Diseases
Like most garden flowers, sweet peas can be affected by a few unwelcome visitors. The most common pests of sweet peas include:
- Aphids – tiny sap-sucking insects that cluster on stems and buds
- Thrips – small insects that damage flower petals
- Slugs and snails – especially a threat to young seedlings
They’re also susceptible to diseases like:
- Powdery mildew – white, dusty fungus on leaves
- Fusarium wilt – soil-borne disease causing yellowing and wilting
Organic Pest Control Methods
Combat pests and diseases with eco-friendly solutions:
- Use insecticidal soap or neem oil for aphids and thrips
- Introduce beneficial insects like ladybugs
- Handpick slugs and snails, or use copper tape around pots
- Improve air circulation to reduce fungal infections
- Water at the base of the plant, not overhead
Healthy, well-spaced plants with proper care are naturally more resistant to problems.
Topics Related To Planting flowers:
How to Maintain a Healthy Sweet Pea Plant
Once your sweet peas are in full bloom, regular care and observation can help you maintain a healthy plant through the entire season. With a few strategic practices, you’ll enjoy longer-lasting flowers and even collect seeds for next year’s garden.
Watch for Overwatering and Nutrient Deficiencies
Signs of overwatering include yellowing leaves, drooping stems despite wet soil, and root rot. On the other hand, nutrient deficiencies may show up as pale leaves, weak growth, or reduced flowering.
To avoid these issues:
- Water only when the top inch of soil is dry
- Stick to a balanced feeding schedule
- Check soil drainage—sweet peas dislike waterlogged conditions
Seasonal Care Tips
Sweet peas are sensitive to both frost and extreme heat:
- In cold climates, protect early seedlings with cloches or row covers
- In hot climates, mulch well and provide partial afternoon shade to extend the blooming season
- Keep an eye on weather changes and adjust watering accordingly
Pruning and Controlling Vines
As sweet peas grow, they may become unruly. Light pruning and training vines regularly will encourage bushier growth and better airflow, which helps prevent mildew.
- Pinch out the tips of young plants to promote side shoots
- Gently tie vines to trellises as they grow
- Remove any weak, tangled, or non-flowering stems
Collecting Seeds from Heirloom Sweet Peas
If you're growing heirloom sweet peas, you can easily collect seeds for next season:
- Allow a few seed pods to fully mature and dry on the plant
- Once they turn brown and start to rattle, harvest them
- Store seeds in a cool, dry place, labeled with the variety (a great time to reuse your seed packet envelopes!)
Note: Only save seeds from open-pollinated or heirloom varieties, as hybrids may not grow true to type.
End-of-Season Cleanup and Composting
When blooming has finished and plants begin to fade:
- Cut plants at the base rather than pulling them to avoid disturbing roots of nearby plants
- Remove any diseased foliage and compost the healthy parts
- Clean trellises and garden supports to prevent future pest buildup
Proper cleanup reduces the risk of overwintering diseases and sets the stage for next year’s success.