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 grab 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 make 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!
sowing sweet pea seeds
Sweet pea seeds have a tough shell. Before sowing, you might want to let them sit on some damp kitchen paper for 24 hours to help with germination.
Between October and April, bury sweet pea seed. The best options are loo rolls or rootrainers since they offer a long, slender root run. It doesn’t allow the roots as much opportunity to grow and branch out if you plant into a short, stumpy pot.
Use a peat-free, all-purpose potting compost to plant the seed; plant two seeds per container. With your finger, put each seed into the compost 2-3 cm below the surface after dampening it. Then, if necessary, label the pot.
Sweet peas can be germinated in a cold frame or unheated greenhouse if they are sown in the spring or fall. Germinate them on a windowsill, heated propagator, or very gently heated greenhouse if you are sowing in the middle of winter.
Keep sweet pea seeds away from mice or try soaking them in liquid seaweed fertilizer before planting to make them tasteless because mice love to eat sweet pea seeds and your entire crop can disappear in one shot.
Daily check for germination; don’t water until seedlings appear; this normally takes 10–14 days. Keep the seedlings cool at around 5C as they emerge (40F). What you want is for this to encourage root growth rather than stem growth. Usually, a cold frame or greenhouse without heating is adequate.
Pinch out the leaders when there are three or four leaf pairs. Simply pinch off the growing tip with your finger and thumb. With the plant’s energy focused on spreading out instead of developing upward, this encourages the growth of robust side shoots.
If the surface of your plants starts to seem dry, check them frequently and give them a little water. Look for white roots at the bottom of the pot around a month after germination.
If you sown your sweet peas in the spring, you can plant them outside right away in a moderate stretch from March to May. You must plant the seeds in pairs if you planted them in the fall or winter. They won’t be the same again if you let them become pot-bound in the rootrainers. It’s best to use a narrow, deep, one-liter saucepan. Water them in and use a decent compost. It’s time to plant the roots outside once the roots have filled that pot. Do this from March through May while it’s mild.
planting sweet pea seedlings
Dig a lot of organic material into the planting location once your seedlings are ready to be transplanted. Farmyard manure is beneficial for sweet peas since it feeds these hungry plants softly and helps keep water on a soil with adequate drainage.
Make sure your sweet peas are planted next to a vertical structure like a teepee, an arch, or a tunnel. For each rod of a vertical support, plant two plants. Spread them out 15 cm (6 in) apart.
Protect them from slugs all around. I utilize a minimum of a 30 cm (1 foot) wide by 5 cm (2 inch) deep piece of washed inland rough sand.
Tie the young sweet pea plants into the frame as they start to grow; do not let them flop around. They’ll produce plants that are stronger and grow more swiftly when consistently tied in. When they start to run off, repeat this more frequently after the first two times in the first month.
After the first month in the ground, feed your sweet pea plants every two weeks. This is especially crucial if the soil is not very fertile. It is best to use a tomato or comfrey feed.
Once the flowers start to bloom, gather as many as you can to fill your vases. Snip any seed pods you come across as you’re cutting them off as well. Your plants must not produce seeds because doing so would prevent them from blooming.
Due to the energy required to create the flower, sweet pea stems naturally get shorter as the season goes on. Feed, water, and deadhead your plants frequently to promote greater flowering.
growing sweet peas in a pot
In deep pots with a climbing frame, sweet peas can be grown. Make sure to select a dwarf or compact variety. A little teepee for a pot can be made or purchased. To build one, firmly press birch or hazel twigs approximately 120 cm (4 feet) tall into the compost around the pot’s perimeter, about 30 cm (1 foot) below. Using twine or a flexi-tie, gather the ends and bundle them at the top. Then, the sweet peas can climb the twiggy teepee.
When should I indoor-sow 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.