Sweet peas are an old-fashioned favorite, with colorful, lacy blooms and bright green vines that never lose their appeal. Sweet peas are a cool weather plant, and will fill an empty space in the garden after the spring bulbs have faded and before the summer flowers take their place. Bringing them in for use in floral arrangements will cause them to produce even more blooms.
Work some balanced granular fertilizer into the soil when you plant the sweet peas, applying it according to the directions. Don't apply fertilizer after this time, because doing so can encourage bushy green growth at the expense of sweet pea blooms.
Spread a layer of organic mulch around the base of the plants after they're 4 to 6 inches tall. The mulch will keep the ground cool and moist.
Install a sturdy trellis for the sweet peas, or plant them next to a wall or fence, because at maturity, the sweet pea vines will be 5 to 10 feet long. .It's best to install the trellis when the sweet pea plants are small, because installing them later can injure the roots. Attach the sweet pea vines to the support with string or stretch ties.
Keep the soil consistently moist, but don't overwater, as too much moisture will cause the sweet pea plants to mold. To avoid fungus, always water the plants in the morning so the moisture will evaporate by evening.
Deadhead sweet peas daily by pinching off or cutting the spent flowers. This will encourage the vines to continue blooming profusely. You can also cut the sweet peas for use in long-lasting indoor arrangements.
Cut the sweet pea vines to ground level when they're done blooming for the season. Leave the roots in the ground so the nitrogen in the plant's root system will help to nourish existing plants.