Sweet Pea Seeds: How to Sow, Grow, and Harvest Them
If you love cut flowers as much as I do, sweet peas are a must-grow. I’m sharing how to harvest sweet pea seeds and how to sow and grow them so your garden is filled with beautiful, sweet-smelling blooms by late winter and early spring.
On my blog WM Design House, I may sometimes use affiliate links, which means a small commission is earned if you purchase via the link. The price will be the same whether you use the affiliate link or go directly to the vendor’s website using a non-affiliate link. Read my full disclosure policy here.
On my blog WM Design House, I may sometimes use affiliate links, which means a small commission is earned if you purchase via the link. The price will be the same whether you use the affiliate link or go directly to the vendor’s website using a non-affiliate link. Read my full disclosure policy here.
Sweet Pea Seeds: How to Sow, Grow, and Harvest Them
The soft colors, delicate petals, and unforgettable fragrance of sweet peas make them a favorite in summer gardens and cut flower arrangements. If you’ve ever wondered how to grow sweet peas from seed or save seeds from your own plants, you’re in the right place.
I’m sharing everything you need to know about sweet pea seeds. From when to plant them and how to sow them successfully, to harvesting your cut flowers and saving seeds for next year. Sweet peas are easier to grow than you might think!
What Are Sweet Peas
Sweet peas (Lathyrus odoratus) are fast growing, cool season annuals known for their climbing habit and sweet fragrance. Most varieties grow as vines and need support, making them perfect for trellises, arches, fences, and garden obelisks.
Sweet peas bloom in shades of pink, purple, white, blue, and cream, and the more you cut them, the more they flower. That makes them an excellent choice for a cut flower garden, and a favorite in many gardens, including mine.
When to Plant Sweet Pea Seeds
Timing is one of the most important factors when growing sweet peas successfully. Sweet peas prefer cool temperatures and will struggle once warm weather arrives.
In cool or moderate climates, sweet pea seeds can be planted outdoors in late winter or very early spring, as soon as the soil can be worked. Sweet peas tolerate light frost and actually benefit from cooler growing conditions.
In mild or warm climates, sweet peas are best planted in the fall. Fall planting allows the plants to establish strong root systems over winter, which leads to healthier plants and earlier blooms in spring.
If you want to get a head start, sweet peas can also be started indoors 6 to 8 weeks before your last frost date and transplanted outside once conditions are suitable.
Sweet peas are a cool season flower, and planting time varies greatly depending on climate. Here is a quick planting guide to help you determine the best time to start or sow sweet pea seeds in your area.
|
Climate Type
|
USDA Zones (Approximate)
|
Indoor Start Time
|
Direct Start Time |
|---|---|---|---|
|
Cold Climate |
Zones 3-6 |
Start indoors 6-8 weeks before the last expected frost. Use deep pots and keep seedlings in a cool, bright location. |
Direct sow outdoors as soon as the soil can be worked in late winter or very early spring, even if light frost is still possible. |
|
Mild Climate |
Zones 7-8 |
Indoor starting is optional. If starting indoors, sow seeds 6–8 weeks before the last frost and transplant once soil is workable. |
Direct sow outdoors in fall, about 6–10 weeks before the first expected frost, allowing roots to establish over winter. |
|
Warm Climate |
Zones 9-10 |
Indoor starting is generally not recommended, as sweet peas prefer cooler outdoor conditions. |
Direct sow outdoors in late fall or early winter when temperatures cool. Fall planting produces the strongest plants and earliest spring blooms. |
Tip from wendy’s Garden:
If you are unsure of your hardiness zone, you can check the USDA map to find out.
Preparing Sweet Pea Seeds for Planting
Sweet pea seeds have a hard outer coating that can slow down germination. Taking a few extra minutes to prepare the seeds before planting often leads to faster and more reliable sprouting.
One helpful technique is scarification, which simply means lightly scratching or nicking the seed coat. You can do this with sandpaper, a nail file, or the tip of a knife. The goal is to help water penetrate the seed coat, not damage the seed.
After scarifying, soak the seeds in room temperature water for 12 to 24 hours. When the seeds are ready to plant, they should appear slightly swollen. If some seeds don’t swell, scarify them again and re soak.
How to Choose the Right Location for Your Sweet Peas
Choosing the right location to plant sweet peas is essential for healthy growth and a vibrant display of flowers. Sweet peas thrive in a spot with plenty of sunlight, ideally, at least six to eight hours of full sun each day.
Sweet peas are heavy feeders, so enriching the soil with compost before planting will give them a strong start.
While they can tolerate light afternoon shade, especially in hotter climates, they perform best with ample morning sunlight.
Sweet peas also prefer well-drained, fertile soil rich in organic matter.
Tip from wendy’s garden:
Adding perlite to your soil improves drainage. Perlite also retains some moisture, providing a balance that helps keep the soil hydrated without becoming waterlogged. This is especially useful for plants that prefer well-drained but consistently moist soil, like Sweet Peas.
How to Sow Sweet Pea Seeds
Sweet peas can be sown directly in the garden or started indoors, depending on your climate and planting schedule. I’ll share steps and helpful tips for each method so you can decide which one is best for you.
How to Start Sweet Pea Seeds Indoors
Starting sweet peas indoors is a great option to give your plants a head start. Especially if your garden soil stays cold or wet in early spring.
Because sweet peas develop long roots, use deep containers, root trainers, or peat pots.
If you’re ever unsure whether your seedlings need water, the finger test is an easy way to check. Simply press your index finger into the soil near the base of the plant, about an inch or so down.
If the soil feels dry and your finger comes back clean, it’s time to water.
Tip from wendy’s Garden:
Avoid using heat mats. Sweet peas germinate best in cooler temperatures.
How to Direct Sow Sweet Pea Seeds Outdoors
Direct sowing Sweet Pea seeds works well in areas with cool springs or mild winters. Don’t forget! You’ll want to be sure to plant your seeds after the last spring frost.
Tip from wendy’s Garden:
The best way to water young plants is to gently water them at the base using a watering can with a fine spout or a spray nozzle set to a light mist. This prevents disturbing the delicate roots and avoids splashing soil onto the leaves, which can lead to fungal diseases. Keep the soil moist but not soggy, ensuring it does not dry out completely.
Once your Sweet Pea seedlings emerge, thin them to about 6 inches apart to allow room for strong growth.
How to Prepare Your Soil for Planting
Before direct sowing your seeds or transplanting seedlings, preparing well-drained soil is a crucial step. Sweet Peas are very particular and do not like their roots soaked.
Mix in Compost: The ideal soil for sweet peas is loamy, which means it has a balanced mix of sand, silt, and clay. This provides good drainage while retaining enough moisture for the roots. To enrich the soil, incorporate organic matter like compost, well-rotted manure, or leaf mold to improve its texture and nutrient content in your garden beds.
Till and Level the Soil: Tilling and leveling the soil creates a loose, even bed that helps to create well-drained soil and root penetration, providing an ideal environment for sweet peas to thrive.
Test Soil PH: The best soil pH for sweet peas is between 6.5 and 7.5, which is neutral to slightly alkaline. This pH range allows sweet peas to absorb nutrients effectively, promoting healthy growth and abundant flowering.
If your soil is too acidic (below 6.5), you can raise the pH by adding garden lime.
For soils that are too alkaline (above 7.5), incorporating organic matter like compost or peat moss can help to balance the pH.
Tip from wendy’s Garden:
Checking your soil from time to time helps keep the pH just right for growing sweet peas. If you’re not sure what your soil pH is, you can pick up an easy test kit at your local garden center, order one online, or even get help through your local extension office.
Sweet Pea Germination and Early Care
Sweet pea seeds typically germinate within 7 to 21 days, depending on soil temperature and moisture levels. Ideal germination temperatures are between 55 and 65 degrees.
Once your seedlings emerge keep your soil evenly moist, provide plenty of bright light to prevent leggy growth.
After your seedlings are in the garden, it’s a good idea to watch for pests like slugs and snails. They’re especially drawn to young plants, so a little early protection goes a long way.
Helpful Tips for Growing and Caring for Sweet Peas
Growing sweet peas is relatively easy. Follow a few helpful growing and caring guidelines, and you will have fragrant, sweet peas for a couple of weeks to months in your garden. They provide lovely cut flowers.
Supporting Sweet Pea Plants
Sweet peas are climbers and need support early in the growing process. Installing a support structure like a trellis, netting, or obelisk at planting time prevents damage to roots later and encourages healthy growth and an abundance of blooms.
Providing support early helps plants grow upright and also helps keep flowers clean and easy to harvest.
Tip from wendy’s Garden:
As your sweet peas grow, gently guide your tendrils onto your support to encourage proper growth. If needed, you can tie tendrils loosely with garden twice for additional support.
Controlling Pests and Diseases
It’s important to check your sweet pea plants for early signs of pests like aphids, slugs, snails, and spider mites. Early detection makes it easier to manage pests before they cause significant damage.
Use neem oil or insecticidal soap to control common pests like aphids, spider mites, and diseases like powdery mildew. Apply these organic treatments directly to the affected areas, following the product instructions for safe use.
Tip from wendy’s Garden:
Natural predators are a gardener’s best friend! Encourage beneficial insects like ladybugs, lacewings, and predatory beetles that feed on aphids and other pests. Planting companion flowers such as marigolds, alyssum, or dill is an easy (and affordable!) way to attract these natural predators and help keep your sweet peas safe.
Pinching Seedlings
When seedlings reach about 4 to 6 inches tall, pinch off the growing tips.
Pinching encourages branching and results in fuller plants with more flowers later in the growing season.
Fertilizing
The best fertilizer for sweet peas is a balanced, all-purpose fertilizer with an equal ratio of nitrogen, phosphorus, and potassium (such as a 10-10-10 or 20-20-20 formula).
Alternatively, a fertilizer formulated for flowering plants, which is slightly higher in phosphorus to encourage blooms, can also be effective. Seaweed emulsion is also a favorite for feeding sweet peas.
You can also use homemade fertilizers like crushed eggshells or spent coffee grounds.
Avoid high-nitrogen fertilizers, as these can promote excessive leaf growth at the expense of flowers. Instead, opt for a slow-release granular fertilizer at planting time, followed by a diluted liquid fertilizer every 4-6 weeks during the growing season to support continuous blooming.
Additionally, incorporating compost or aged manure into the soil before planting can provide a steady source of nutrients and improve soil health.
Watering
The best way to water sweet peas is to provide deep, consistent watering at the base of the plant, ensuring the soil stays evenly moist but not waterlogged.
Water in the morning to allow excess moisture to evaporate throughout the day, reducing the risk of fungal diseases.
Use a soaker hose or drip irrigation system to deliver water directly to the root zone, avoiding wetting the leaves, which helps prevent mildew and other leaf diseases.
Increase the watering frequency during hot or dry weather to maintain consistent moisture levels. However, always allow the top inch of soil to dry slightly between waterings to prevent root rot.
Pruning
Regular pruning is beneficial for sweet peas to encourage continuous blooming and healthy growth.
Tip from wendy’s Garden:
If your pruning shears start crushing stems instead of cutting cleanly, it’s probably time to sharpen them. A quick touch-up with a sharpening stone or file can make a big difference and takes just a few minutes.
Deadheading, or removing spent flowers, is essential to prevent the plant from setting seeds, which would otherwise signal the plant to stop producing new flowers.
Common Sweet Pea Growing Problems
If your sweet peas aren’t thriving, one of these common issues may be the cause:
Poor Germination: Soil too warm, seeds not scarified, or inconsistent moisture
Lots of Leaves but Few Flowers: Too much nitrogen fertilizer
Short Blooming Season: Warm weather arriving too early
How and When to Harvest Sweet Pea Flowers
Harvest sweet peas regularly to encourage more blooms. The best time to cut flowers is early in the morning when the stems are hydrated.
To cut your flowers, identify a healthy stem, cut just above a leaf node or a pair of leaves, and place them in water immediately. Frequent harvesting encourages new growth, additional flower production, and keeps your sweet pea plants blooming longer.
Sweet Pea Harvesting Tips
Here are some more helpful tips and things to look for to know when your beautiful sweet peas are ready to be harvested. Your sweet peas are ready to be picked when:
They are in full bloom: The flowers are fully open, displaying their vibrant colors and characteristic shape, but not starting to wilt or fade. Harvesting at this stage ensures the flowers are at their most fragrant and visually appealing.
They have firm petals: The petals should feel firm and not show any signs of browning or curling at the edges. This indicates that the flowers are fresh and in peak condition for harvesting.
They have a strong stem: The stems should be sturdy and firm, not floppy or weak. Strong stems will hold up better in arrangements and last longer once cut.
There are no visible seed pods: If you want to prolong blooming, harvest the flowers before seed pods form. Once the plant produces seeds, it reduces flowering and focuses on seed development.
Sweet Pea Vase Life
Sweet pea arrangements generally do not have the longest vase life, typically lasting 4 to 7 days when cut.
To help keep your sweet peas fresh as long as possible, harvest the flowers early in the morning when they are most hydrated. To further maximize their vase life, cut the stems at an angle and place them in water immediately, and refresh the water daily.
How and When to Harvest Sweet Pea Seeds
Collecting seeds from mature sweet pea pods allows you to preserve your favorite varieties and continue their legacy in your garden.
With a little attention to timing and the proper seed harvesting techniques, you can enjoy the charming beauty of these delicate flowers from season to season.
Here’s a simple guide to harvesting sweet pea seeds.
When to Harvest Sweet Pea Seeds
Sweet pea seeds are small, round, and have a hard seed coat, typically dark brown or black. They’re easy to collect and store, making them ideal for gardeners who want to grow flowers from seed.
As the summer heat sets in, your plants will dry up and turn brown, making this the ideal time to harvest your seeds.
Sweet pea seeds are harvested from mature seed pods once they turn a papery brown color.
The timing for harvesting sweet pea seeds depends on your growing zone. I usually harvest my seeds in Southern California (Zone 10b) in late July or early August.
However, in most other parts of the country, sweet pea seeds are typically ready for harvest closer to early September, at the end of the growing season.
How to Know When Your Seeds are Ready to be Harvested
Here are some more helpful signs to look for to know when your pods are ready, and your seeds are ready to be harvested.
When they turn brown: The most important indicator is the color and texture of the pods: they should turn from green to light brown, resembling the appearance of a paper bag.
If they feel brittle: The pods will also feel dry and brittle to the touch, and you may hear a slight rustling sound when they are shaken, signaling that the seeds inside have matured and loosened.
When they have split: At this stage, the pods may start to split slightly along their seams, another sign that the seeds are fully developed and ready to be collected.
The Best Time of Day to Harvest Sweet Pea Seeds
The best time to harvest sweet pea seeds is in the early morning, ideally on a dry day when any dew has evaporated.
Morning harvesting ensures that the seeds are cool and not exposed to the intense heat of the day, which can affect their viability. A dry day prevents moisture from seeping into the seed pods, reducing the risk of mold or rot during storage.
Tip from wendy’s garden:
Collect your seeds on a flat tray lined with a paper towel to avoid the seeds from sliding around
How to Collect Sweet Pea Seeds
Tools Needed
Techniques for Collecting seeds
A simple technique for saving the pea-like seeds from your garden is gently squeezing the dried sweet pea seed pods along their seams.
Hold the pod over a clean tray or bowl, then use your fingers to carefully apply pressure along the seam until the pod splits open. Once open, use your thumb to brush the seeds out into the tray or bowl gently.
Use caution. This method helps prevent seeds from scattering and makes collecting them all in one place easy.
Afterward, spread the seeds in a single layer on the tray and leave them in a cool, dark place for a few days to ensure they are completely dry before storing them.
Tip from wendy’s garden:
When clipping the pods, hold a large baggie underneath to collect them. Then, shake the bag well, and many seeds will fall out of the pods.
How to Store Sweet Pea Seeds
To properly store sweet pea seeds, place them in a paper bag or envelope, allowing air circulation and preventing moisture buildup that could lead to mold or rot.
Ensure the paper bag or envelope is labeled with the seed variety and the collection date to keep track of freshness.
Store the seeds in a cool, dry place, such as a cupboard, pantry, or drawer, away from direct sunlight and humidity. A temperature of around 40-50°F (4-10°C) is ideal for seed storage.
Tips for saving sweet pea seeds
To further protect the seeds, consider placing the paper bags inside an airtight container, such as a glass jar with a lid or a plastic container with a tight seal.
This added layer helps protect against any potential pests or unexpected humidity changes. Check on the seeds occasionally to ensure they remain dry and will be ready to sow when the planting season arrives.
Tip from wendy’s garden:
Be sure to write on the envelope the name of the seeds and the date.
Common FAQ’s About Sweet Peas
Q: How long do sweet peas take to germinate?
A: Sweet pea seeds usually take about 10 to 14 days to germinate, depending on soil temperature and conditions.
Q: How tall do sweet peas grow?
A: Climbing varieties of sweet peas can grow up to 6 to 8 feet tall or more, while bush varieties are more compact, growing about 1 to 3 feet tall.
Q: How can I encourage more blooms on my sweet peas?
A: To encourage more blooms, deadhead spent flowers regularly, provide consistent watering and fertilization, and ensure they receive plenty of sunlight.
Other Gardening Posts from WM Design House
If you love this post about sweet pea seeds, you might also enjoy some of my other favorite gardening posts:
39 of the Best Perennials
Make Your Own Plant Fertilizer
Are Zinnias Perennials
Wrapping Up
In summary, growing sweet peas can be a rewarding experience, offering a stunning display of colorful and fragrant blooms throughout the season. By understanding their planting needs, providing the right care, and managing pests effectively, you can enjoy these beautiful flowers in your garden year after year.
Whether growing annual or perennial varieties, following these simple tips will help you cultivate healthy, vibrant sweet peas that add charm and fragrance to any outdoor space.
Happy gardening!
More about me!
Hello, I’m Wendy – a dedicated homemaker with a deep passion for decorating, gardening, cooking, and crafting. I find joy in harmonizing beautiful elements to fashion a space that is both comfortable and inspiring. I will help you create a beautiful home, one project at a time.
love your Sweet Peas! and your gardening instructions are amazing!
Thank you, Patty. I love spending time in the garden It’s my happy place.