When to Plant: Sweet peas can withstand light frosts, therefore in cold winter regions, sow in seed starting pots in early spring approximately 6-7 weeks before the final day of frost. Then, plant out as soon as the soil can be handled.
Sweet pea seeds can be directly placed into the garden in the fall from September to November in mild winter settings where the ground does not freeze. This will allow the seeds to develop healthy root systems and bloom in the spring.
If you give your seeds a head start by sowing indoors in seed containers from late January through March and transplant into the garden as soon as the soil can be worked, you can still receive a decent harvest of sweet peas, even though they will bloom a bit later. Sweet peas can handle light frosts.
1. Before planting, you could decide to nick your sweet pea seeds. The seed’s outer layer can be broken off by giving it a quick cut with a nail clipper so it can quickly absorb water. This will result in a higher percentage of your seeds germinating and a few days earlier sprouting.
This is how: Between your thumb and forefinger, hold a seed. Clip your seed by holding the clippers at an angle with the other hand so that you can only utilize the tip of the blade. Not taking a chunk out of the seed is your goal; it is to slice through the brown top layer of the seed. Sometimes the nick you caused is barely visible, and other times a bit of the seed coat cracks off revealing the interior seed’s lighter color. Both are true.
2. Avoid using garden soil when planting sweet peas in containers. Use high-quality potting mix instead. Using garden soil can lead to issues like compaction and poor drainage, whereas potting mix recipes are designed to perform under the circumstances found in a small container. In garden centers, a variety of soil mix brands are easily accessible.
Before filling your container, always pre-moisten your potting mix. As you slowly pour water into a bucket or wheelbarrow and stir the dirt, the earth will become evenly moist. When it feels like a wrung-out sponge, you are finished.
A 3 to 4 inch container works well for starting sweet peas. To prevent spreading disease to your new soil mix, properly clean the pot before using it again. After adding the pre-moistened mixture to the pot, give it a quick tap on the work surface to settle the soil. When a pot is filled correctly, the soil surface will be about 1 inch below the container’s top.
3. The time has come to plant your seeds. It matters how deeply you plant them. Always adhere to the planting depth recommendations on your packet’s back. Make a hole that is 1 deep for sweet peas. For this, a pencil or your finger works great.
4. Insert the seed into the opening you created. In order to ensure that every pot eventually gets a plant, even if one seed does not germinate or dies, we advise sowing two seeds each pot.
If you decide to plant 2 seeds per pot, you will need to thin them after the first set of leaves appear to 1 seedling per pot. At the soil line, trim or pinch out any surplus seedlings. Pulling it out could damage the surviving seedling’s roots, so avoid doing so.
5. Cover your seed with soil mixture after sowing. To remember what you planted when and how much of it, we advise labeling your containers with the variety and the date.
6. Lightly mist the seeds you covered. Use a watering can or hose with a diffuser attachment to let the water fall gently like rain. This will stop the water from washing the dirt away or compacting the soil too much.
Create the ideal circumstances for germination as you wait for your seedlings to appear. The two most critical variables are water and temperature. Your soil should always be damp, but not drenched. The ideal soil temperature is between 55 and 70 °F. You can start your seeds outside if the weather permits. A greenhouse or your home must be used to start them otherwise. Provide protection from birds, snails, and slugs if beginning them outside.
You must give your seeds a decent source of light once they have sprouted. If you want to keep them inside, you can put them beside a window as long as the sun won’t make them too hot during the day. Sweet peas do not have an issue with cooler nighttime temperatures near a window. Another option is fluorescent lighting. However, for the intensity to be bright enough, plants should be placed between 6 and 12 inches from the lights.
7. If you started your seeds indoors, the seedlings must be hardened off before being transplanted into your garden. Hardening off is the process of gradually exposing your plants to the elements they will experience outside, with temperature and direct sunlight being the most important factors. If you don’t, your seedlings can have transplant shock once they are planted in the garden.
When your plants have around 3–4 pairs of leaves, you can begin the hardening off procedure. Place your plants outside where they will receive morning sun in full force and afternoon shade. If you don’t have access to such a place, you will need to relocate your plants every day so that they are in the morning sun and out of the afternoon sun. Move them to a location where they will receive direct sun all day after about 3–4 days. You can move them into your garden in a few more days.
8. You can pinch or chop off the top of your seedlings when they have 3–4 pairs of leaves, leaving 2-3 pairs of leaves. Your cut should be made just above two leaves. By encouraging lateral branching, pinching helps you grow plants that are fuller.
9. Since sweet peas require healthy, well-drained soil, add some aged manure or other finished compost into your garden bed before planting. Work the material into the soil and rake the bed to level it out.
To move your seedling, make a hole that is both deep and wide enough to accommodate the root ball.
10. Try to minimize root disturbance while transferring your sweet pea seedlings from their container. Try it. Put one hand over the top of the pot, the seedling in your fingers, and flip the pot over to catch the root ball. Using the other hand, gently touch the bottom of the container while squeezing the edges to release the soil and plant.
11. Insert your seedling into the resulting hole, then cover it with soil. It is crucial when transplanting sweet peas that the soil level remain the same as it was in the pot. The plants may become sickly, stunted, or even die if you bury too much of the stem.
12. Leave 5 to 6 feet between each transplant. Your mature sweet peas’ health depends on the proper spacing between plants. Additionally, it provides the roots of individual plants with enough room to forage for water and nutrients while also enhancing air circulation to help avoid disease.
13. Gently water in your seedlings as soon as you are done transplanting. In addition to giving the plant water, this settles the garden soil around the root ball to prevent huge air pockets from drying out the roots. Use a watering can or hose with a diffuser attachment to water your plants, which will make the water fall gently like rain instead of washing the dirt away or beating your tender seedlings.
Tall sweet peas require a sturdy support in order to ascend. Build one now so that it is there when your seedlings are prepared to begin climbing.
14. You must keep birds, snails, and slugs away from your sweet pea seedlings. In order to prevent these typical predators from discovering your sprouts and eating them before you even realize they are up, you should do this as soon as possible after sowing your seed.
Use netting for birds. We create our own support hoops out of polytube, which is a flexible, black plastic irrigation tube that is sold at most reputable garden centers. It should be cut into lengths that correspond to the width of your garden beds. To create arches over your sweet pea bed, bury the ends of the cut tubing in the ground. These arches should be covered with bird netting, which should be secured at all edges to prevent openings. Before your sweet peas grow large enough to attach themselves to the netting, remove it. We choose the product Sluggo for snails and slugs because it is safe for use on people, pets, and wildlife.
15. You might want to assist stray branches in locating their vertical support structure as your plants grow higher and begin to climb. Encourage them to cling to you gently. Branches of sweet peas quickly break.
16. We advise deadheading to prolong the blooming period of your sweet pea plants. This entails removing wasted flowers before they have an opportunity to use their energy to produce seeds rather than other blossoms. Deadheading is best done right when the bloom has peaked and is just starting to fade. Cut the entire flower stem off at all times.
17. The blossoming of this plant is fully complete. When you can see, the plants begin to slow down and eventually stop flowering altogether as the discarded blooms turn into seedpods. Whether you deadhead or not, all sweet pea plants eventually reach the end of their flowering season. However, you can extend the bloom time by removing spent blossoms.
18. The flowers are, of all, the whole reason of producing sweet peas. Don’t forget to frequently clip them and bring them inside. They create lovely bouquets with the most amazing scents. Additionally, the plant will produce more blossoms the more you cut!
When should I indoor-sow my sweet pea seeds?
In regions with warm winters, you can start seedlings inside in late January. (For the following year, prepare to immediately plant the seeds in the garden in the fall; they will develop throughout the winter into roots and bloom early in the spring.) Sweet peas should be planted inside about six weeks before the anticipated last frost date in areas with cold winters. Les Brake, an Alaskan gardener, offers tips on growing sweet peas. As soon as the soil can be worked in any location, transplants can be placed outside. Light frost won’t harm sweet peas. The majority prefer cool weather, while certain species, such the heirloom Lathyrus matucana, can tolerate mild heat. Since sweet peas often bloom in the spring, you should plant them as soon as you can. Lathyrus belinensis is a plant that blooms later and has interesting coloration.
Sweet peas should be sown in containers indoors:
Use a sharp knife to make a small cut in the tough outer shell of the seed coat. The seed will sprout more quickly as a result.
Fresh seed-starting mix should be poured into four-inch plastic pots or pots made of biodegradable materials (such as newspaper or Cowpots) and properly dampened. With your finger, a dibber, a pencil, or something similar, make a 1-inch-deep hole, then place one to three seeds within. Add extra mixture on top.
If more than one seed sprouts, cut off any more seedlings at the soil line so that each container only contains one plant. The seedlings should be grown in a sunny area, such as next to a window that faces south or on a light stand. The tops of the seedlings should remain 6 inches away from the bulbs if artificial lighting is being used.
Pinch or prune seedlings when they have four sets of leaves, right above the third set. The plant will become bushier and more branched as a result of this.
Before transferring seedlings outside, harden them off by gradually exposing them to sunlight and open air over the course of a week or so, leaving them out for a little bit longer each day. Put them on a soil that drains well and is rich. When moving plants, take care not to harm their roots. Squeeze the pot’s walls to help the root ball slip out. Handle the plants by their leaves and hold the entire root ball in your palm. You can simply plant the entire container in the ground if you used peat pots or anything similar.
Seedlings should be planted 6 inches apart and at the same depth as they were in their pots. Use a watering can with a rosehead to water softly. Sweet peas are annual climbing flowers. Give your sweet peas something to grow on, like a lattice, a twine frame, or netting with holes that are at least 2 inches square.
Before planting, are sweet pea seeds soaked?
- Sweet peas can be seeded in the fall in warmer places (Zone 7 and above) where the winters are generally not too harsh. Other than that, plant seeds in late winter or early spring. Before planting, give the seeds a 24-hour soak in water. By doing so, the seed coat is softer and the sprouting process is accelerated.
- Fill your planting containers with high-quality potting soil while the seeds are soaking. Use the deepest pots you can find because sweet peas develop a lot of roots. Ideal containers are 4-inch (10-cm) pots and root trainers.
- In each container, plant two seeds by pressing a fingertip into the soil and a half-inch (1.25 cm) deep.
- To boost humidity and hasten germination, cover pots with a plastic dome covering. Place in a warm greenhouse or a house window with good light.
- Pinch out the center growth tip, just above a leaf joint, once plants are 4 to 6 inches (10 to 15 cm) tall, leaving just two or three leaf nodes. The plant will be encouraged to branch out strongly from the base as a result.
- Because they use a lot of food, sweet peas need a little more care to produce in large quantities. Apply bone meal, a thick layer of compost or well-rotted manure, and a generous amount of natural fertilizer to planting beds to prepare them. Incorporate these elements thoroughly into the soil.
- Vines require a sturdy foundation to climb and grow quickly. Affix Hortonova netting or 6-foot (1.8 m) tall metal fence to the tall poles spaced approximately 8 feet (2.4 m) apart down the row for them to climb.
- Around the time of the final spring frost, plant seedlings outdoors in two rows, one on either side of the trellis, spaced approximately 8 inches (20 cm) apart down the row. It’s crucial to keep the vines bound to their supports as they erupt into lush growth. Sweet peas can grow more than a foot (30.5 cm) per week once the vines begin going.
- Sweet peas adore water, and they can’t survive without regular watering. Set up soaker hoses as soon as you plant them to prevent their luxuriant development from being restrained. It’s important to maintain their thirst quenched during warm weather. Use diluted fish and seaweed emulsion to feed plants once a week.
- Pick flowers when there are at least two unopened blooms remaining on the stem for the greatest vase life. To extend the life of the vase, add flower food to the water. It’s crucial to prevent plants from going to seed in order to prolong blooming, so be sure to regularly harvest and deadhead the flowers.