How to grow Lathyrus (Sweet Pea) Seeds
Sweet peas are colourful, fragrant climbing flowers that grow best in a sunny location with well-draining, fertile soil.
Sowing Sweet Pea Seeds
If planting indoors, start seeds 6–8 weeks before the last frost date. Sow the seeds about 2.5 cm deep in seed trays or small pots, and keep the soil consistently moist.
Germination & Spacing
Place the trays in a cool spot with temperatures around 10–15°C until they germinate, which usually takes about 10–15 days. If sowing directly outdoors, sow seeds about 2.5 cm deep and space them 5–7 cm apart.
Location & Soil
Start by choosing a sunny location with well-draining, fertile soil. Sweet peas thrive in full sunlight but can tolerate some light shade. Before planting, improve the soil by adding compost to ensure good drainage and fertility.
Direct Sowing Outdoors
If you prefer to sow the seeds directly outdoors, wait until all risk of frost has passed and the soil has warmed up to about 10°C. Prepare your garden bed by loosening the soil and ensuring good drainage. For a vertical display, plant them near a trellis or fence so they can climb as they grow.
Support & Watering
Sweet peas are climbing plants and will need support as they grow. Provide a trellis, mesh netting, or other vertical structure for the vines to attach to. Water consistently, especially during dry periods, but avoid overwatering or letting the soil become waterlogged, as this can lead to root rot.
Feeding & Flowering
Fertilize lightly with a balanced fertilizer once the plants begin to grow, but avoid high-nitrogen fertilizers, which can result in lush foliage at the expense of flowers. As the plants mature, remove spent flowers regularly to encourage more blooms.
Sweet peas are known for their rich, sweet fragrance, and deadheading will help maintain a tidy appearance and promote continuous blooming throughout the season.
Height & Cut Flowers
Sweet peas generally grow to a height of around 1–2 meters, depending on the variety. They will begin flowering in early summer and continue through late summer or early fall. The colourful, fragrant blossoms are perfect for cutting and adding to bouquets.