It is said that "actions speak louder than words." Although this may be true with human beings, when it comes to old fashioned sweet peas, "fragrance speaks louder than looks." The most fragrant varieties of sweet peas often produce small blooms in pastel colors. Larger bloomed varieties sport vivid hues of scarlet and deep maroon, but often lack the heady sweet fragrance associated with sweet peas. For gardeners, that often means sacrificing one for the other, but some varieties retain qualities of both.
Prepare a garden bed for sweet peas in a location that receives full sun. Till to a depth of 8 to 12 inches. Amend with a 2 to 3 inch layer of compost or well-rotted manure. Work into the existing soil.
Plant sweet peas in the spring once the soil has warmed to 55 to 65 degrees F.
Scarify sweet peas seeds by nicking the seed coat with a sharp knife or filing a break in the coat. Place in a cup of water and allow to soak overnight. Viable seeds absorb water and swell to double in size. Discard any seeds that float or fail to swell, as they will not germinate.
Sow seed to a depth of 1 inch spaced 2 inches apart in rows. Cover with soil and firm down with your hands to secure the seed and remove air pockets.
Water thoroughly and keep soil moist until seedlings emerge in 10 to 28 days, depending on the soil temperature and weather.
Pinch out center leaves on seedlings when they reach a height of 4 inches. Squeeze new leaves between your forefinger and thumb to remove them from the stem. This encourages new growth along the stem and creates dense foliage.
Provide a trellis for tall varieties as soon as young tendrils form. Sweet peas climb vigorously twining around trellises or over fences.
Fertilize once a month with water-soluble fertilizer. Follow the application rate for flowering plants.
Deadhead faded blooms by pinching or clipping them free of the vine to encourage prolonged blooming.