Sweet Pea Growing Essentials

• Soil pH is best at neutral to alkaline.
• Amend the area with compost or well-aged manure in fall; this will condition the soil.
• Sow seeds in pots and place in a cold frame or greenhouse during October.
• Sow in containers indoors January to March for spring planting outdoors. Spring-sown plants will be 3 weeks later than autumn-sown plants.
• To provide good seed germination, nick the seed coat with a nail clipper or use sand paper to penetrate the seed coat, but don't overdo it. This is especially needed for mottled and black-seeded varieties. Soaking seeds overnight is not advised and may prevent germination. White, brown and wrinkle-seeded varieties should never be nicked.
• Sow five to seven seeds per five-inch container filled with a sterile potting mixture.
• To prevent rotting of soft-seeded varieties in containers, add extra peat and perlite or horticultural sand to sowing medium.
• When planting seeds, water immediately after sowing, and then refrain from watering until seedlings emerge. Do not over-water seedlings.
• Repot seedlings into 3-inch pots before the first leaves begin to open.
• Pinch out the growing tip once seedlings have grown two pairs of leaves. This will encourage side shoots and bushier plants.
• Prepare an outdoor garden area about 3 feet wide. Cultivate the soil until fine and crumbly to the feel. Early autumn is a good time to amend the soil with compost and or manure.
• In spring insert a row of 8-foot bamboo canes, 18 inches apart along the prepared garden area. Attach string or twine to bamboo about 3 inches apart for seedling tendrils to climb up.
• From mid-March to mid-April, plant seedlings along supports.
• Sweet pea seedlings can take a light frost.
• Proper placement of seedlings in the garden is essential. Bright light without too much hot direct sun is best. Don't plant in shade of overhanging tree branches. Do not place on a fence or wall with hot direct sun.
• Mulch plants after planting to conserve moisture. Drip irrigation works well.
• Sufficient light and rain must be available, but too much sun and heat can encourage mildew.
• Tendrils can only grow on string, twine, or netting that is not thicker than 1/4 inch in diameter.
• Sweet peas can be grown as trailing plants in large containers, making a waterfall of color.
• Protect large plantings from birds with highly reflective Mylar ribbon or netting. 
• To conserve soil moisture around plants, mulch with grass clippings. Spring plantings will need more water as days grow longer and warmer.
• Fertilize with manure tea or organic plant food monthly.
• Cut flowers every few days to promote continuous new blooms. Deadhead spent blossoms to extend the flowering time and to prevent plants from going to seed, if preferred.
• Replace damaged seedlings with young seed plants; they will soon catch up.
• Seeds are toxic if consumed.  Keep out of reach of children and pets.
• A good variety of sweet peas to grow is the Spencer series.

Seed Savers Exchange is an excellent source of seeds.