Sweet Peas

How to Grow Sweet Peas from Seed:

Sweet peas (Lathyrus odoratus) are beloved for their ruffled petals, heavy fragrance with many colours.
A classic cottage garden flower, they're easy to grow with a little know-how and perfect for cut flower arrangements and containers.

Link to - Sweet Peas Infographic to download.
Grow Sweet Peas Calendar - Infographic

How to Grow Sweet Peas from Seed:

Choosing the Right Variety:

1. Select from heirloom, Spencer, or dwarf types depending on your space.
2. climbing varieties need support; bush types are ideal for containers.

Soaking Sweet Pea Seeds:

To soak or not to soak: I usually don't and it works just fine.

1. Sweet pea seeds have a hard coat. Some suggest to soak the seeds in warm water for 8-12 hours before planting to improve germination. No difference for me.
2. Avoid nicking the seed with a knife, which can introduce disease. I don't nick any seeds of any kind.

When to Plant Sweet Peas In Canada:

1. Start indoors 6-8 weeks before the last frost or sow directly once the soil is workable.
   I have done both, but I would rather direct sow for convenience, save space indoors and on "hardening off" plants outdoors. I works well for me in zone6.
2. Pinch sweet peas when they are around 6" tall and plant about 6" apart.
   I also remove sweet pea tendrils if sown indoors, before the sweet peas get all tangled with each other.

Soil Preparation for Sweet Peas:

Sweet peas prefer rich, well-drained soil with a pH between 6.0 and 7.5.
Work in compost or well-rotted manure before planting.

Sun & Support for Sweet Pea Vines:

Plant in full sun (at least 6 hours daily). If your summers are hot - sweet peas appreciate some shade in the afternoon.
Sow seeds 1 inch deep, thin to - 2-3 inches apart.
Use a trellis, netting or obelisk for climbing types to prevent mildew and encourage airflow. I use the same metal fencing as for climbing beans since I'm growing sweet peas just as a cut flower.

Watering sweet peas:

Keep soil consistently moist, especially during flowering.
Avoid overhead watering to reduce fungal diseases.
Mulch helps retain moisture.

Pinching & Pruning :

Pinch back seedlings when 4-6 inches tall to encourage bushier growth.
Deadhead spent blooms regularly to prolong flowering.
Sweet peas benefit from fertilizers that are high in phosphorus and potassium but low in nitrogen.
Too much nitrogen encourages leafy growth at the expense of blooms.

Ideal Fertilizer Type for Sweet Peas:

Balanced or bloom-boosting fertilizers with an N-P-K ratio such as:

1. 5-10-10
2. 10-20-20
3. 0-20-20 (especially if soil is already rich in nitrogen)

Recommended Fertilizer Options:

1. • Bone Meal - High in phosphorus; promotes strong root and flower development.
2. • Liquid Bloom Fertilize - Like Miracle-Gro Bloom Booster (15-30-15), diluted and applied every 2-3 weeks.
3. • Compost and worm casting Tea - Gentle, organic, and boosts soil health without excessive nitrogen.
4. • Seaweed or Kelp Extract - Adds micronutrients and potassium to support flowering and stress resistance.

When to Fertilize Sweet Peas:

1. • At planting: Mix compost and/or bone meal into the soil.
2. • Once established: Start fertilizing every 2-3 weeks after the first true leaves appear.
3. • During bloom season: Continue with a low-nitrogen bloom fertilizer to keep flowers coming.

Common Pests & Diseases on sweet peas:

1. • Aphids: Rinse with water or use insecticidal soap.
2. • Powdery Mildew: Improve airflow and avoid wetting leaves.
3. • Root Rot:Ensure good drainage; avoid waterlogged soil.
4. • Pea Thrips: Cause distorted blooms; use sticky traps.

To Attract Pollinators & Beneficial Insects:

1. • Nasturtiums - Attract aphids (trap crop), pollinators and hoverflies.
2. • Calendula - Draws ladybugs and lacewings that eat aphids.
3. • Sweet Alyssum - Low-growing, helps suppress weeds, and attracts pollinators.

Harvesting sweet peas for Vase Life:

Cut blooms early in the morning when flowers just open. Use clean, sharp scissors and immediately place in water.
Vase life is 4-6 days; re-cut stems daily.
For optimal vase life, sweet pea stems should be cut when 1-2 blooms are open, with some unopened blooms remaining at the tip. Indoors - my sweet peas only lasts about 4 days.

How to Grow Sweet Peas in Containers:

Choose the Right Container for Sweet Peas:

1. • Size: Minimum 12 inches deep and wide; larger is better for root development and moisture retention.
2. • Material: Terracotta, plastic, or wood - ensure good drainage (add extra holes if needed).
3. • Drainage Layer (optional): Use broken pottery or gravel at the bottom to prevent water-logging.

Potting Mix for Sweet Peas:

Use a high-quality potting mix with:

Good drainage
Added compost or worm castings
Mix in some bone meal or slow-release fertilizer for phosphorus.
Or mix your own potting soil at homes-n-gardens.com

Planting & Soaking Seeds:

1. Soak seeds in warm water for 8-12 hours before planting to soften the hard coat. It works without soaking the seeds.
2. Plant 1 inch deep, 2-3 inches apart.
3. If using starts, transplant carefully to avoid disturbing roots.

Light Requirements for Sweet Peas:

Place in full sun (6+ hours/day) with some shade.
Avoid hot reflective surfaces—sweet peas prefer cooler roots.

Support for Sweet Pea Vines:

Use a small trellis, bamboo canes, or obelisk in the container.
Dwarf/bush varieties need minimal support, but climbing types must be tied gently as they grow.

Watering Sweet Peas:

Keep soil evenly moist, especially during flowering.
Containers dry out quickly—check daily in warm weather.
Avoid overhead watering to prevent mildew.

Feeding Sweet Peas in Containers:

Use a liquid bloom fertilizer (ie. 5-10-10 or 10-20-20) every 2-3 weeks.
Avoid high-nitrogen fertilizers which lead to leaf growth, not flowers.

Deadheading & Care for Sweet Peas:

Pinch tips when 4-6 inches tall to encourage bushiness.
Deadhead regularly to keep blooms coming.
Cut flowers often to extend bloom time.

Pest & Disease Watch:

Watch for aphids, powdery mildew and slugs.
Ensure airflow around the plant to reduce fungal issues.

Best Varieties of Sweet Peas for Containers:

1. • 'Cupid' - A dwarf variety with fragrant pink-and-white flowers.
2. • 'Little Sweetheart' - Bushy, colorful and container-friendly.
3. • 'Bijou Mix' - Compact and blooms well in pots.
4. • Dwarf heirloom types - Often more fragrant and suited for containers.

All about Seeds and Seedlings
Printable Seedpackets and Seedpacket Dividers
Chart for Seed Germination with light and without
All about Flowers