Sweet Peas: How to Grow and Care for Sweet Peas

Sweet peas (Lathyrus odoratus) are beloved garden flowers cherished for their delicate appearance, climbing habit, and enchanting fragrance. Originating from the Mediterranean region, these flowering plants have captivated gardeners worldwide with their ability to add vertical elegance and vibrant color to any outdoor space. Whether you’re an experienced gardener or a beginner, this guide offers everything you need to know about planting, caring for, and enjoying sweet peas.

Table of Contents

Quick Information Table

Attribute	Details
Common Name	Sweet Pea
Botanical Name	Lathyrus odoratus
Family	Fabaceae
Plant Type	Annual (some perennial types)
Mature Size	6-10 feet (climbers); 1-3 feet (bush varieties)
Sun Exposure	Full sun
Soil Type	Rich, well-draining, loamy
Soil pH	Neutral to slightly alkaline (6.5–7.5)
Hardiness Zones	Zones 2-11 (as an annual)
Native Area	Mediterranean region
Toxicity	Toxic to pets and humans if ingested

Planting and Transplanting Sweet Peas

Sweet peas require careful planning for the best results. Here’s a step-by-step guide to get you started.

Choosing the Right Location

Sweet peas thrive in sunny locations with good air circulation. Aim for a spot that receives 6-8 hours of sunlight daily. Protection from strong winds is important, as their delicate stems can snap easily.

For climbing varieties, choose locations near a trellis, fence, arbor, or wall. Bush varieties do well in pots, borders, or garden beds.

Preparing the Soil

Amend the soil: Enrich the planting area with compost or well-rotted manure. Sweet peas are heavy feeders and appreciate fertile, organic matter.
Ensure drainage: Avoid planting in waterlogged soil, as sweet peas are prone to root rot. Incorporate sand or grit if the soil is heavy clay.
pH adjustment: Test the soil and maintain a pH between 6.5 and 7.5. If the pH is too low, add lime to raise it.

Planting Time

Spring planting: In temperate climates, sow seeds 4-6 weeks before the last frost date. Start seeds indoors if necessary.
Fall planting: In mild or Mediterranean climates, sow seeds in the fall to establish root systems for early spring blooms.

Transplanting Sweet Peas

When transplanting seedlings, timing is crucial. Move them to their permanent location when they have two sets of true leaves.

Dig holes spaced 6-8 inches apart for climbing varieties and 4-6 inches apart for bush types.
Handle the roots delicately, as they don’t tolerate disturbance well.

Sweet Peas Care

Watering

Sweet peas need consistent moisture, but soggy soil can lead to diseases. Water deeply about once or twice a week, depending on weather conditions.

Mulch: Apply organic mulch around the base of the plants to retain moisture and keep the roots cool.
Watering tips: Always water at the base of the plant to prevent fungal diseases on the leaves.

Fertilizing

Begin with a balanced fertilizer (e.g., 10-10-10) when seedlings are 4-6 inches tall.
Switch to a fertilizer high in phosphorus and potassium, such as bone meal or a bloom booster, when flower buds appear.

Supporting Climbers

Install trellises, poles, or netting before planting to avoid disturbing the roots later. Use soft garden ties to gently secure stems to the supports. Train them upward by regularly guiding their tendrils.

Types of Sweet Peas

Sweet peas come in a variety of forms, each offering unique beauty and characteristics.

Grandiflora

These heirloom varieties are prized for their intense fragrance and small, delicate blooms. While not as vigorous as hybrids, they are ideal for gardens focused on scent.

Spencer Hybrids

A favorite for flower shows, Spencer hybrids have large, ruffled flowers on long stems. These are perfect for cutting gardens and floral arrangements.

Dwarf or Bush Varieties

These compact plants don’t climb but instead grow into tidy mounds, making them ideal for containers or garden edges. Examples include the Cupid series.

Perennial Sweet Peas (Lathyrus latifolius)

Unlike annual sweet peas, perennial varieties lack fragrance but are hardy and long-blooming. They are excellent for low-maintenance gardens.

Pruning

Pruning is essential to maintain healthy growth and encourage abundant blooming.

Deadheading

Remove faded or wilted flowers promptly. This prevents the plant from diverting energy into seed production and encourages more flowers.

Pinching

Pinch off the top 1-2 inches of growth when the plant reaches 4-6 inches tall. This encourages branching and results in bushier growth.

Removing Weak Growth

Cut back spindly or damaged stems to focus the plant’s energy on healthy vines and flowers.

Propagating Sweet Peas

Sweet peas are most commonly propagated from seeds, but you can also propagate perennial varieties from cuttings.

Seed Propagation

Scarify the seeds: Use sandpaper to gently scratch the seed coat. This improves germination rates.
Soak seeds: Soak seeds in warm water overnight to soften the seed coat and hasten sprouting.
Plant: Sow seeds 1 inch deep and 2 inches apart in seed trays or directly in the garden.

Propagation by Cuttings (For Perennials)

Select healthy stems and cut 4-6 inch sections.
Dip the cut end into rooting hormone.
Place the cutting in a pot with moist, well-draining soil. Cover with a plastic bag to retain humidity until roots develop.

How to Grow Sweet Peas From Seeds

Starting sweet peas from seeds is a straightforward process that yields rewarding results.

Step-by-Step Instructions

Prepare Seed Trays: Fill with seed-starting mix, which is lightweight and nutrient-rich.
Plant Seeds: Sow seeds about 1 inch deep. Cover lightly with soil.
Maintain Temperature: Keep trays in a location with temperatures between 55°F and 65°F. Use a heating mat if necessary.
Provide Light: Place the trays in a sunny window or under grow lights for 12-16 hours daily.
Watering: Mist the soil lightly to keep it consistently moist but not waterlogged.

Once seedlings develop their second set of leaves, they are ready for transplanting.

Potting and Repotting Sweet Peas

Growing sweet peas in containers is a great option for those with limited garden space.

Potting

Choose a pot at least 12 inches deep with drainage holes.
Fill with a high-quality potting mix rich in organic matter. Add a slow-release fertilizer.
Support climbing varieties with a small trellis or stakes.

Repotting

Repot sweet peas when they outgrow their current container or when the soil quality declines. Gently lift the plant, shake off old soil, and replant in fresh mix.

Overwintering

Sweet peas are generally annuals but can be overwintered in mild climates or with special care.

Steps to Overwinter

Apply a layer of mulch around the base to protect roots from frost.
Use row covers or frost cloths during cold nights.
Water sparingly to prevent rot.

Common Problems With Sweet Peas

Yellowing Leaves

Caused by overwatering or nutrient deficiencies. Ensure well-draining soil and apply a balanced fertilizer.

Stunted Growth

Often the result of poor soil quality or lack of sunlight. Provide adequate nutrients and ensure at least 6 hours of sunlight daily.

Common Pests & Plant Diseases

Pests

Aphids: Control with insecticidal soap or neem oil.
Slugs and Snails: Use physical barriers like crushed eggshells or diatomaceous earth.

Diseases

Powdery Mildew: Improve airflow around plants and apply a fungicide.
Root Rot: Avoid waterlogging and ensure proper drainage.

How to Get Sweet Peas to Bloom

For abundant blooms, focus on the following:
1.

Regular Feeding: Use a bloom-specific fertilizer.
2. Adequate Sunlight: Ensure at least 6-8 hours of sunlight daily.
3. Deadheading: Remove spent blooms promptly.

FAQ

1. How long does it take for sweet peas to bloom?

Sweet peas typically bloom 12-14 weeks after sowing seeds. Early planting and consistent care ensure a faster bloom cycle.

2. Why are my sweet peas not fragrant?

Certain sweet pea varieties, such as modern hybrids, may lack a strong fragrance. Choose heirloom or Grandiflora varieties for the best scent.

3. Can sweet peas grow indoors?

Sweet peas can be grown indoors if they receive enough light, such as near a bright window or under grow lights. Ensure good air circulation to prevent mildew.

4. Are sweet peas safe for pets?

No, sweet peas are toxic to pets and humans if ingested. They contain compounds that can cause vomiting, lethargy, or more severe symptoms.

5. Do sweet peas grow back every year?

Most sweet peas are annuals and require replanting each year. However, perennial sweet pea varieties (Lathyrus latifolius) will return annually but lack fragrance.