Sweet pea seeds should be directly put into the garden in the fall from September through November in mild winter settings where the ground does not freeze in order to develop robust root systems and blossom in the spring. If you are unable to plant your seeds in the fall, start as soon as spring arrives in a well-drained area that provides some afternoon shade.
In regions with difficult winters, plant about a month before the last date of frost after the worst of the weather has passed. If spring arrives early in your region and becomes hot and muggy, mulch seedlings well and place them where vines will have some afternoon shade.
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. Since sweet peas require fertile, well-drained soil, add some aged manure or other finished compost to your garden bed before planting. Work the material into the soil and rake the bed to level it out. Make a furrow with a stick or a tool. Make sure your furrow is 1 inch deep since it’s crucial to plant seeds at the correct depth (for sweet peas, this is 1 inch).
3. When planting your seeds, space them 2-3 inches apart in your furrow. You have a better chance of getting a full bed of plants with no gaps if you sow your sweet peas at this spacing. You will thin your seeds later, when they have grown, to the desired spacing.
4. After sowing, fill in your furrow with earth to cover the seeds. You should only transfer enough soil to fill in the trench without building up a mound above the seeds since you want your seeds to be positioned one depth down.
5. Lightly mist the seeds you covered. To stop the water from washing away the soil, use a watering can or hose with an attachment that diffuses the water so that it showers gently like rain.
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.
6. 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. Using flexible, black plastic irrigation tubing, often known as polytube and sold at most garden centers, we create our own support hoops. 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.
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. 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.
9. The blossoming on this plant is completely through. 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.
10. The flowers are, of all, the whole idea of cultivating sweet peas. Remember to cut some and bring them inside; they make lovely, sweet-smelling bouquets. Additionally, the plant will produce more blossoms the more you cut!
spring
- From March to May, you can easily plant your young sweet pea plants outside. Before planting out, sweet pea seeds sown in the winter or autumn need to be potted up into larger containers. Spring-sown seeds can be transplanted from their rootrainers.
summer
- Pick your sweet peas, then put them in indoor vases. Remove the seed pods from your sweet peas to continue deadheading them. You’ll need to harvest and deadhead them frequently when they’re at their height.
Sweet peas can withstand how much cold?
As annual plants, sweet peas (Lathryus odoratus) complete their whole life cycle in a single growing season. This traditional flower germinates well in cool environments, but if the plants are not covered, frost and freezing temperatures can cause damage to sweet peas. Direct sow sweet peas outdoors in late fall in warmer areas to enhance winter and spring blooms. Young seedlings can survive cold snaps if they are shielded from abnormally low temperatures.
Tip
Sweet peas can withstand a slight frost, but immature seedlings can freeze in temperatures below 25 degrees Fahrenheit. To ensure your cutting garden flowers will endure chilly nights in the early spring, protect sweet peas when low temperatures are anticipated.
Choosing sweet peas and perennial peas
The major consideration is whether or not aroma is crucial to you when deciding between perennial Lathyrus and sweet peas. Decide if you would then like an annual or perennial plant. There are several color choices available as well as climbing and bushier varieties.
Fragrance
Choose sweet peas (Lathyrus odoratus), which are generally very fragrant, if you enjoy a pleasant garden and sweet-smelling flowers for indoor use.
Lord Anson’s blue pea (Lathyrus nervosus), a perennial Lathyus, is an exception to the rule since it does have a perfume.
How long the plant lasts
After setting seed, sweet peas (Lathyrus odoratus) only have a one-year lifespan. However, don’t let this deter you because they are quite simple to grow from seed. Lathyrus latifolius is an example of a perennial species that returns every year, however there are fewer options and they typically lack smell.
Habit
The majority of Lathyrus are climbing plants, therefore support them with canes, netting, or allow them to climb over a bank or through a bush. For ground cover and pots, clumping varieties like the spring-flowering Lathyrus vernus and dwarf bushy sweet pea varieties like “Snoopea” and “Bijou Mixed” are excellent choices.
Buying sweet peas and perennial peas
Although many garden centers also sell a few sweet pea seeds in packets, the largest assortment of sweet pea seeds may be acquired from internet seed suppliers. In the spring, several nurseries and garden centers sell pots of germinated sweet pea seedlings that can be divided into individual plants and raised in pots before being planted outside.
There are a few seed specialists who sell perennial Lathyrus seeds, like Lathyrus latifolius, but many gardeners opt to purchase the plants instead. The plant you’re looking for can be found using our Find a Plant tool.
When to plant sweet peas and perennial peas
- Annual sweet peas should be sown either in late January or early April and planted out in April.
- Sow perennial Lathyrus in the spring or the fall.
Where to plant sweet peas and perennial peas
Locate a sunny area where there is room for the plant to grow or to bush out (depending on its habit). Also acceptable is a little light shade, especially for Lathyrus grandiflorus.
How to plant sweet peas and perennial peas
- To avoid cold shock, indoor seedlings should be hardened off for 10–14 days before being transplanted outside.
- Ideally, four weeks before planting, enhance the soil by incorporating a soil conditioner like garden compost or manure.
- Sprinkle general-purpose fertilizer, as directed on the pack, into the area where you plan to plant it, such as Growmore, Vitax Q4, or blood, fish, and bones.
- Before planting, water your plants thoroughly to hydrate the roots.
- Remove pots from larger plants and ease seedlings out of modules or pots while being careful not to snap or crush the stems.
- Plants should be separated by 20–30 cm (8–1 ft).
- Place climbing plants near to their intended support (within 5-7.5cm or 2-3in), with two plants at the foot of each cane if they are climbing a wigwam.
- After planting, water once more to help the soil surrounding the roots settle.
Use garden twine or sweet pea support rings to secure young climbing plant shoots to canes, pea sticks, netting, trellis, or shrub shoots that they will be growing up. Tendrils in contact with supports will naturally start to cling on, but if any are straying or in danger of snapping, keep tying in new shoots.
In dry weather, check on plants in the ground every 3 to 4 days and on those in containers every day because they won’t flower as well if they become too dry. Each time you water, be sure to use enough water to completely moisten the roots.
Apply a high potassium liquid fertilizer, such as tomato feed, once or twice a week on light or infertile soils. This promotes flowering, particularly in annual sweet peas (Lathyrus odoratus).
Pick or remove dead flower heads as frequently as you can once flowering starts. For annual sweet peas (Lathyrus odoratus), which will stop flowering if seedpods are allowed to form, this is especially crucial.
Pinching out
When plants are around 7.5 to 10 cm tall, pinch out the shoot tips of new spring-sown sweet peas for gardening (3-4in). This promotes robust side branching. Autumn-planted seedlings frequently naturally branch.
Cordons
Pick the strongest shoot and keep pinching out all the tendrils and other sideshoots as they grow whether you want to enter your sweet peas in a local show or just want to maximize the size of blossoms for cutting. By using this technique, the plant directs its attention to the blossoms. The term “cordons” is used to describe these single-stemmed plants.
One stem per bamboo cane or tall stake needs to be tied to them on a regular basis. To keep the shoot in place as it grows, you can use twine looped in a figure-eight pattern around the cane and stem. Use sweet pea rings, which are wire loops that wrap around the stem and cane and are lightly squeezed until they hold, to make things simpler.
Cordons have the potential to grow much taller than the typical 2 m (6 1/2 ft) estimated height.
Cutting back
Cut perennial Lathyrus back to the ground in the fall, or better still, wait until February to do it so the dead stems can serve as wintertime cover for wildlife. When flowering is ended at the end of the summer, annual sweet peas can simply be pulled out and composted. This might happen a little bit sooner during hot, dry seasons.
Methods
Sweet peas can be immediately sown into the ground in April, or they can be planted in seed compost pots in the fall or spring. Although it takes more time, pot-sowing is typically more dependable than direct sowing. If you plant in the fall to enhance your chances of getting early blooms, keep seedlings in a coldframe or cold greenhouse over the winter to protect them from growing lanky. Keep the coldframe’s lid elevated unless a strong frost is anticipated. Sweet peas planted in the spring flower in 12–14 weeks.
Sweet pea seeds frequently have a tough outer covering that makes them more challenging to germinate. Place your seeds on a layer of damp vermiculite or kitchen tissue and store them in an airtight container in a warm area. As soon as the seeds swell or start to sprout, plant them. Some gardeners like to soak the seeds overnight instead, but if you don’t plant them right away thereafter, they might rot. With a sharp penknife, chip off a little portion of the hard seed coat to allow moisture to enter and promote germination on recalcitrant seeds that haven’t swelled.
- Individually sow seeds in seed compost-filled rootrainers or 9 cm (3 in) pots. As an alternative, sow five to seven seeds per 13 cm (5 in) pot, spacing them 2-3 cm (3/4-11/4 in) apart.
- Add 1 cm (1/2 in) of vermiculite or compost to the top of the seeds.
- Add water and maintain at around 15C. (59F)
- It is optional to cover the pots with clear polythene or glass to reduce the likelihood that they will dry out, but keep in mind to remove the covering after the seeds have germinated.
- Once they have grown to around 3.5 cm (11/2 in), carefully transplant single seedlings into 9cm (3 in) pots if you have seeded them several to a pot.
- Use your thumb and finger to pinch out (remove) the top of the shoot just above a healthy leaf when the seedlings are 7.5–10cm (3–4in) tall. This will promote side branches, which are always stronger than the core stem that has been removed.
- At least four weeks before planting, remove all weeds from the soil and add a soil enhancer, such as garden compost, manure, or composted bark.
- Only plant seeds as the soil begins to warm, typically around April.
- To create a wigwam, plant any temporary supports, like pea sticks or bamboo canes, in the ground.
- Take out a shallow drill of dirt 2.5 cm (1 in) deep for rows of sweet peas, and plant a seed every 5 to 7.5 cm in it (2-3in)
- Seedlings should eventually be spaced 20–30 cm (8–1 ft) apart to provide the plants enough room to flourish. The extra seedlings may seem like a waste to compost, but unless treated carefully, their roots are typically too damaged to recover.
- Push two seeds into the ground at the base of each cane to a depth of 2.5 cm (1 in) when sowing around a wigwam of canes.
Perennial peas
In the spring or the fall, divide bigger plants. If you want to divide Lathyrus vernus in the spring, wait until after flowering.
Unfortunately, very few of the issues with sweet peas and perennial peas are extremely problematic.
- Powdery mildew, which is brought on by drought or insufficient hydration, results in a grey leaf coating.