Sweet peas typically grow best in the spring and early summer and thrive in chilly, damp settings. They frequently go to seed and disappear at the height of the summer.
You can plant them in the fall or late winter if you live in a warmer environment. People from colder climates might begin them in the early spring.
In Michigan, the last spring frost typically occurs around May 15. About 4-6 weeks prior to that, I attempt to plant my sweet peas.
Around the time that you would grow edible garden peas, sweet peas can be planted in the garden. On Good Friday, which is generally in the first week of April, I always plant my garden peas.
They need soil that is rich and well-drained. Try planting them in raised beds if your spring garden struggles with the moist soil. Those are “heavy feeders, which means they are ravenous for food.
I dig a trench, fill it with thoroughly decomposed manure, cover it with soil, and then plant there “trench filled with compost
(*NOTE: Sweet peas are NOT edible and are actually thought to be a dangerous plant, so proceed with caution if you’re around young children or animals.)
Transplants or Direct Sow?
Sweet peas can be planted directly or transplanted. Both methods may benefit from soaking the seeds for up to 24 hours prior to planting to improve germination rates.
Before planting them outdoors, transplants can be started indoors 4–5 weeks in advance. They can be planted outside when there is a chance of frost because they are fairly tough (mine frequently get covered in snow, and they survive just fine!).
You can jump start the season with transplants, but you should be aware that Sweet Peas are picky about where they are placed. Their root systems do not like to be disturbed in the slightest.
Give each pot or container two seeds. Planting sweet peas in the deepest containers you can find will give them the space they need to grow strong roots. Four pots, such as those tomato plants typically come in, will do. Alternately, you might use peat pots, which will naturally decompose in the landscape.
Be VERY patient because the seeds can take up to 3 or 4 weeks (!!!) to germinate. Once they have sprouted, they can be transplanted to the garden and progressively hardened off.
No matter how gentle you are with their roots, it’s usual for them to “pout” for around 3–4 weeks after being replanted in the garden. They wait there, precisely as they did when you first placed them in, until one day they snap out of it and begin growing like crazy. Be tolerant!
Put them in the ground if you’re direct-sowing around six weeks before your last spring frost. Put two seeds in each hole. While you wait for the seeds to sprout, make sure the soil is kept consistently moist.
By properly wetting the area after planting the seeds and covering it with a thick layer of straw, I’ve had wonderful success with direct sowing (about 6-9 deep). The straw prevents birds and other bothersome animals from trying to consume the seeds by keeping the soil equally moist. Periodically remove the mulch to check for germination.
After the seeds have sprouted, straw works well as a mulch to keep the soil cool and moist.
The ideal sweet pea spacing is six inches. They are a climbing vine that can grow up to 10′ tall and require a support of some sort in order to flourish.
when to plant sweet peas
When between October and April, plant sweet pea seeds. Aim for late October or late November or late February or early March for the best outcomes because midwinter temperatures and light conditions aren’t the optimum. In April or May, sweet peas can also be planted directly into the ground. During a moderate period between March and May, sow your sweet pea seeds and plants.
Can sweet peas be planted directly into the ground?
With an autumn sowing, sweet peas can be planted early. All you need is a frost-free, cool place to store them for the winter.
The majority of individuals plant the seeds in the spring as soon as the temperature rises. Typically, seeds are first seeded indoors before being put outdoors in a garden. From late April, you can seed directly in the ground, but the outcomes might be less predictable.
When in doubt, always keep sweet peas away from frost and follow the recommendations on the packet for your particular variety.
How much time do sweet peas need to grow?
The fragrant, sweet aroma that is released by the blossoms of annual sweet peas (Lathyrus odoratus) gives them their name. The fall, winter, and early spring garden seasons in warm, Mediterranean settings are perfect for this annual flowering vine because it prefers mild temperatures. In the spring and early summer, sweet peas grow best. Plant hardiness zones 4 through 7 of the United States Department of Agriculture are suitable for perennial sweet peas (Lathyrus latifolia). Depending on the cultivar, sweet pea blossoms come in a variety of hues, including white, purple, pink, red, orange, blue, and lavender.
When can I plant outside sweet peas?
Sweet peas are available in a wide variety of hues and designs. The majority will only reach a height of 5 or 6 feet, while shorter “bush type” variants are ideal for containers. Pick a few different varieties to extend the flowering season. Find types that bloom early (“short-day”) and late by reading the seed packs (“long day). Even though annual sweet peas predominate, perennial sweet peas are also available (Lathyrus latifolia).
Start early
It’s crucial to start sweet peas (Lathyrus odoratus) blossoming early so they can survive the summer heat because they like chilly temperatures. As soon as the soil can be handled in the spring, you can plant them outside. The seeds will likely be alright even though it will likely still be very chilly. Sweet peas can be planted in the south in late fall for late winter or early spring blossom. Consult local cooperative extension to learn about best practices in your community.
Start your peas inside for the longest blooming season possible. Timing is determined by the date of your region’s last frost. Back up the date by four to six weeks once you get it. You should then plant. For instance, you should plant in early to mid-April if your last frost date is May 15. Don’t know when your region last experienced frost? Consult local cooperative extension or a reliable gardener in the area.
Sweet peas can they withstand frost?
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.
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.
Sweet peas can withstand how much cold?
According to Gardeners’ World (opens in new tab), sweet peas should be treated like any other non-hardy annual: “Plant your sweet peas outside starting in late May, after all danger of frost has passed. Put them outside throughout the day and bring them inside at night to harden them off before planting.
The most recent edition of Sarah Raven’s podcast (opens in new tab) claims, however, that “Sweet peas are hardy and can go in the garden from the middle of March.”
Confused? So were we up till we learned the RHS’s excellent sweetpea-growing tips (opens in new tab) (watch in the video above). Sweet peas are in fact “extremely tough,” says Propagation Leader Sam Gallivan, and they can withstand frosts “with no issue at all.” They do struggle with extended cold and rainy times, though. Your young sweet pea plants could perish if you reside in a region where early spring can bring both low temperatures just above freezing and a lot of rain.
Because of this, you have two options: either hold off and plant them outside in April when the weather will be warmer, even if it rains, or keep them in a cold frame until the chilly showers stop. However, sweet peas are typically categorized as half-hardy annuals and can withstand dry frost up to -4C. (25F). You will need to cover them with horticultural fleece in the event that temps fall below that.
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.
Colour
The annual sweet pea (Lathyrus odoratus) has a large variety of blossom colors, including bicolored varieties. However, the perennial varieties do come in some uncommon colors, like yellow and orange.
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.