Vining Types

• Vining-type sweet peas have a climbing habit and need support. Their vines can reach 5 to 10 feet long. Among the taller varieties are "Old Spice Mix" and "Royal Family," which respond to training onto trellises and can be used to cover fences, according to the Oregon State University Extension. Sweet peas attach themselves by means of tendrils, but you can provide additional support to guide and separate the vines. With foliage and flowers, individual vines are only 3 to 4 inches wide. Vining sweet peas do not have a dense habit unless you plant a particularly thick stand of plants. Plant these sweet peas 2 to 4 inches apart, and thin them to 4 to 6 inches apart.
  
  

Bush Types

• Bush-type sweet peas vary in height from 3 to 36 inches tall, depending on the variety. Taller bush types may need support, but compact forms, sized under 24 inches, don't require support. Dwarf and short bush varieties have a more dense habit because they grow in a compact form with a spreading mound of foliage and flowers. The Oregon State University Extension suggests "Supersnoop" for a low-growing hedge. The depth of foliage depends on the conditions of the site and the number of plants in a space. Generally, leave 10 to 12 inches between individual dwarf or bush sweet peas. The Ed Hume Seeds website suggests an alternative: planting bush varieties by spacing seeds 2 inches apart in all directions to create a wide row, leaving 24 to 30 inches between rows.
  
  

Conditions

• Annual sweet peas are cool-season plants and need a soil temperatures of 55 to 65 degrees Fahrenheit, according to the Washington State University Extension, which suggests a good rule of thumb is to plant them at the same time as garden peas. Nick the seeds for better germination. Early flowering types need 10 hours of sunlight daily and bloom in winter or early spring, while spring and summer flowering types need 12 to 15 hours of sunlight, notes the extension.
  
  

Perennial Pea

• The perennial peas (Lathyrus latifolius) grow up to 8 feet tall as a supported vine or form an 18- to 30-inch-thick viney mat of foliage if left unsupported, according to the United States Department of Agriculture. Leave a spacing of 2 feet between plants. This pea flowers in mid-summer, producing purple, pink or white flowers. Perennial pea plants provide cover for wildlife and help in erosion control.