Annual Sweet Peas, Lathyrus odoratus, thrive in cool, moist spring climates. The heat of summer is often too much for the plants, but as long as temperatures are 70 - 80°, the flowers do well and a bounty of colorful blooms is produced. The blooms come in all colors except yellow, and there are different varieties that offer early flowering and summer flowering with the latter being more resistant to the heat. Delicate tendrils grasp and climb supportive structures quickly covering the form. There is also a perennial Sweet Pea, Lathyrus latifolius, that is also a climber but it does not have the lovely fragrance, and the colors are limited to rosy-pink, white and red.
Sweet Peas are easily grown from flower seeds. Due to a thick seed coat, it’s generally recommended to nick the seed with a knife tip and soak the seeds overnight in water before sowing. The seeds require a consistent soil temperature of 55 - 65°F for germination. Typically Sweet Pea seeds are sown directly in the garden about the same time as the edible garden peas. Plant the seeds ½ to 1 inch deep and thin the seedlings according to the variety that is being grown. Pinch the growing tips on the young plants to encourage a bushier growth habit. Provide support in the form of a fence, trellis or posts with wire, and help the tendrils attach to the structure so that the plant can begin to climb. After the seedlings are climbing, a layer of mulch over the root area will help keep the roots cool and extend the flower season.
If your garden soil is slow to warm in the spring, Sweet Pea seeds can be started indoors. Once the seeds have sprouted, provide as much light as possible to prevent leggy growth. If possible, place the Sweet Pea seedlings in a cold frame or protected structure where they can grow until the soil temperature is warm enough for transplanting.
Provide full to partial sun for Sweet Peas. The plants prefer rich soil with added organic matter, and keep it evenly moist. Care for Sweet Peas includes regular deadheading of the spent blooms and seed pods to promote re-blooming. The vines will stop blooming if allowed to form seed pods. One often forgotten characteristic about Sweet Peas is that they are in the Legume family. They fix nitrogen from the air, so fertilizers that are high in nitrogen are not recommended as they will only promote vine growth and foliage, but a fertilizer that is high in phosphorus is recommended for flower growth. Aphids love Sweet Peas, so control is sometimes necessary. Slugs and snails also may enjoy eating the tender seedlings, so protection may be needed from these pests. Since powdery mildew is sometimes problematic, it’s best to provide good air circulation around the plants and water in the morning so that leaves can thoroughly dry throughout the day.
Sweet Peas are an old-fashioned favorite flower. They are grown not just for their charming beauty in the garden but also for their continued supply of cut flowers for arrangements. These sweet, colorful blossoms are loved by just about everyone.
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