How to grow Lathyrus (Sweet Pea) Seeds
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, it’s a good idea to improve the soil by adding compost to ensure good drainage and fertility. If you’re 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. Place the trays in a cool spot with temperatures around 10-15°C until they germinate, which usually takes about 10-15 days.
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. Sow the seeds about 2.5 cm deep, and space them 5-7 cm apart. For a vertical display, plant them near a trellis or fence so they can climb as they grow.
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. Be sure to water consistently, especially during dry periods, but avoid overwatering or letting the soil become waterlogged, as this can lead to root rot.
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.
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 colorful, fragrant blossoms are perfect for cutting and adding to bouquets.