How to Plant Sweet Peas from Seeds

Sweet peas are a delightful addition to any garden, known for their vibrant colors and sweet fragrance. Planting them from seeds is a rewarding process that allows gardeners to enjoy their beauty throughout the growing season. With a few simple steps and proper care, you can cultivate these charming flowers and transform your space into a colorful haven. This guide will walk you through the basics of how to plant sweet peas from seeds, ensuring a successful and flourishing bloom.

Why Grow Sweet Peas from Seeds?

Growing sweet peas from seeds offers numerous benefits, making it an excellent choice for gardeners of all skill levels. Starting from seeds allows you to choose from a wide variety of colors and varieties, giving you the freedom to create a truly personalized garden. Additionally, seeds are cost-effective and provide the rewarding experience of nurturing plants from their earliest stages of life. Sweet peas also tend to establish stronger root systems when grown from seeds, resulting in healthier plants and more robust blooms. By growing them from seeds, you can also ensure the plants are cultivated without chemicals, making them an eco-friendly addition to your garden.

Types of Sweet Peas

Sweet peas come in a variety of types, each offering unique characteristics that cater to different preferences and garden styles. Here are some notable types:

• Spencer Sweet Peas: Renowned for their large, wavy petals and delightful fragrance, Spencer sweet peas are a popular choice for gardeners seeking show-stopping blooms. Their sturdy long stems make them excellent for cut flower arrangements.
• Grandiflora Sweet Peas: These heirloom varieties are loved for their delicate appearance and intense fragrance. While their blooms are smaller than Spencer varieties, they exude classic charm and are well-suited for smaller garden spaces.
• Dwarf Sweet Peas: Perfect for container gardens and small spaces, dwarf sweet peas grow to a shorter height without compromising on beauty or fragrance. They are ideal for adding color to patios or window boxes.
• Multiflora Sweet Peas: Known for their abundant clusters of flowers, multiflora sweet peas provide a profusion of blooms throughout the growing season. They are an excellent choice for creating vibrant displays in the garden.
• Striped or Flaked Sweet Peas: These varieties stand out for their unique, colorful patterns on the petals, adding an artistic splash of color to any garden.

When choosing a type, consider the climate, available space, and your desired aesthetic to find the perfect sweet pea variety for your garden. Each type offers its own enchanting blend of beauty and fragrance.

10 Methods How to Plant Sweet Peas from Seeds

1. Choose the Right Variety of Sweet Peas for Your Garden

Before planting sweet peas (Lathyrus odoratus), it’s important to select a variety that suits your growing conditions and aesthetic preferences. Sweet peas come in many cultivars, offering different heights, colors, and fragrance levels. Tall climbing varieties such as ‘Old Spice’ or ‘Spencer Mix’ are ideal for fences and trellises, while dwarf types like ‘Cupid’ are suited for containers or borders. Consider your local climate and whether you prefer an heirloom, modern hybrid, or scented strain. Choosing the right type lays the groundwork for a successful and visually pleasing display of flowers later on.

2. Soak or Nick Seeds to Improve Germination

Sweet pea seeds have a hard, protective outer coating that can delay germination. To speed up the process, soak the seeds in lukewarm water for 8 to 12 hours prior to planting. Alternatively, nick the outer coating lightly with a nail file or small knife, being careful not to damage the inner seed. This scarification helps moisture penetrate the seed coat more effectively. Both methods can help sweet peas sprout more uniformly, especially in cooler soils. Taking time to prepare the seeds properly improves success rates and gets your plants off to a strong start.

3. Start Indoors or Direct Sow Based on Your Climate

Depending on your growing zone, you can start sweet peas indoors or sow them directly into the garden. In regions with long winters or unpredictable spring weather, start seeds indoors 6 to 8 weeks before the last expected frost date. Use biodegradable pots, as sweet peas dislike root disturbance. In milder climates, direct sow the seeds outdoors in early spring or even in late fall in some warmer regions, as sweet peas thrive in cool weather. Adjusting your sowing strategy to your local conditions ensures healthier seedlings and an earlier bloom.

4. Use Deep Containers or Trenches to Support Strong Root Growth

Sweet peas develop deep root systems, so it’s best to plant them in containers that are at least 3 to 4 inches deep, such as root trainers or tall seedling pots. For direct sowing, dig shallow trenches or individual holes about 1 inch deep and space the seeds 2 to 3 inches apart. Cover them with soil and gently firm it down. Deep planting encourages stronger, straighter roots and results in sturdier plants. Giving the roots room to grow from the beginning contributes to greater resilience and more prolific flowering.

5. Provide Full Sun and Well-Draining, Rich Soil

Sweet peas flourish in full sunlight—at least 6 hours of direct sun daily—and in fertile, well-draining soil. Before planting, enrich the soil with well-rotted compost or aged manure to support lush growth and abundant blooms. Avoid overly rich nitrogen fertilizers, which may lead to excessive foliage and fewer flowers. Sweet peas also prefer slightly alkaline soil, so consider adding garden lime if your soil is too acidic. Preparing the soil properly sets the foundation for vigorous, healthy plants that reward you with weeks of colorful blossoms.

6. Water Consistently During Germination and Early Growth

After planting your seeds, water the soil gently but thoroughly to help initiate the germination process. Keep the soil consistently moist but not soggy. During early growth, regular watering is essential, especially in dry or windy conditions that can quickly dry out the soil surface. Use a watering can with a fine rose attachment or a gentle spray setting on your hose to avoid dislodging the seeds. As the seedlings emerge, continue watering to maintain even moisture, which supports steady root development and robust growth from the start.

7. Provide Support Early for Climbing Varieties

If you are planting tall sweet pea varieties, installing supports early is crucial to avoid disturbing the roots later. Use trellises, garden netting, bamboo stakes, or wire fences to give your sweet peas something to climb as they grow. The tendrils will naturally cling and climb upward, but you may need to gently guide or tie the stems early on using soft plant ties or twine. Proper support not only keeps the plants upright and tidy but also improves air circulation and enhances flowering by exposing the blooms to more light.

8. Thin and Transplant with Care if Necessary

Once your seedlings have grown to a few inches tall and developed at least two sets of true leaves, it’s time to thin them. Thin direct-sown plants so that they are spaced 6 to 8 inches apart. This reduces overcrowding and allows for better airflow and light penetration. If you started your seeds in trays or containers, transplant them carefully into their final position, being mindful of their delicate roots. Use a trowel to dig a hole slightly larger than the root ball, and plant at the same depth they were growing in the pot.

9. Pinch Back Tips to Encourage Bushier Plants

When seedlings reach about 6 inches tall, pinch or snip off the top inch of the central stem just above a pair of leaves. This encourages the plant to branch out, producing more lateral stems and, eventually, more flower-producing sites. Pinching results in a bushier, fuller plant and a longer flowering period. While optional, this technique is especially useful for tall varieties and for gardeners aiming for a more dramatic and floriferous display. It’s a simple trick that significantly boosts bloom production throughout the season.

10. Maintain Flowering with Regular Deadheading and Feeding

As your sweet peas begin to flower, regular care will extend the blooming season and keep your plants healthy. Remove spent flowers (deadheading) frequently to prevent the plant from setting seed, which can slow or stop flower production. If you’re growing them for cut flowers, harvesting blooms regularly serves the same purpose. Additionally, feed your sweet peas every few weeks with a balanced, low-nitrogen liquid fertilizer or a bloom booster to encourage continuous flowering. With proper ongoing care, your sweet peas can bloom abundantly from late spring well into summer.

Conclusion

Planting sweet peas from seed is a gratifying process that leads to an enchanting garden display of color, fragrance, and classic charm. From selecting the ideal variety and preparing the seeds through soaking or nicking, to sowing them in rich, well-drained soil and providing climbing support, each step contributes to a successful and beautiful bloom. By maintaining consistent moisture, thinning seedlings, and pinching for bushiness, gardeners can enjoy a profusion of blossoms throughout the season. Thanks for reading, and we hope this has given you some inspiration on how to plant sweet peas from seeds!