Sweet peas are one of the few annual flowers with enduring appeal and rural charm. They appear to be the exact opposite of our hurried life as they twine languidly around a rustic trellis. Sweet peas are fantastic flowers for gardens and bouquets thanks to their alluring scent. For information on how to plant and care for sweet peas, read our Sweet Pea Growing Guide!
About Sweet Peas
The sour pea Lathyrus odoratus is an annual flower that looks great twining on a trellis or arch, growing in a cutting garden, border garden, or woods. Today, a wide variety of hues, from pearly white to ice cream pastels to ritzy magentas and inky purples, are available for the blooms.
Only their honey and orange blossom fragrance matches their delicate winged flowers. Their appeal has been ensured by the combination of their exquisite aroma and their capacity to generate a large number of flowers for the house over an extended time of cutting.
One of the keys to cultivating sweet peas is to sow them early. Sweet peas are incredibly tough, despite the way they appear fragile. Plant them in very late winter or early spring in USDA Hardiness Zone 7 or colder, as soon as the soil is dry enough to work with. (Don’t plant seeds after the last frost.
When Dr. Robert Uvedale, a teacher from Enfield, Middlesex, received seeds of this exceedingly fragrant annual in 1699 from a Sicilian monk named Francis Cupani, he brought the first sweet peas to Britain. In North America, they gained enormous popularity as garden plants and cut flowers. By the late 1800s, producers in California, especially W. Atlee Burpee, were exporting trainloads of sweet peas across the nation and creating numerous new varieties.
Some people liken the process of producing sweet peas to that of preparing pie dough. Some individuals are gifted, while others are not. This plant sprouts from large, manageable seeds that resemble peas. They are still rather challenging since they take a while to germinate. It’s worthwhile to experiment with various seeds every year.
When to Plant Sweet Peas
- Sweet peas should be planted as soon as the soil is dry enough to work in very late winter or early spring in most places where frosts occur frequently (Zone 7 and colder). (Start sowing before the last frost! Most certainly, it will be too late.)
- Plant sweet peas in the late fall (November) if you garden in a region with a mild winter climate (Zones 8, 9, or 10), so they can grow and blossom in the late winter and early spring. Six weeks before you plant the seeds, dig a trench and fill it with compost or well-rotted manure to obtain the greatest show. Sweet peas are gregarious plants that require a lot of nutrient-rich materials to flourish.
Sowing Sweet Peas Indoors
- Start sweet peas inside in a seed tray to get a head start on the season in the coldest regions of the nation. Sweet peas can withstand light frosts, so plant out as soon as the soil can be worked in early spring, around 6 to 7 weeks before the last date for frost.
- The seeds’ outer layer is softened and helped to germinate by soaking them overnight. Using a nail file to lightly score the outer shell can also be beneficial.
- 2 seeds to a module is fine to sow the seeds, but keep in mind that their lengthy roots have a propensity to tangle and can make separation challenging. Sow the seeds around half an inch deep in each cell of a seed tray.
- Scoop them out gently after they start to sprout their first pea-like leaves and place them in a larger container to harden off. One of the most reputable growers of sweet peas gave me the following piece of advice: “Treat the seedlings like I would treat my husband: put them in an unheated greenhouse, neglect them, and they will thrive.
- Plant them outside as soon as the soil can be worked.
Sowing Seeds in the Ground
- Sweet peas thrive when their roots are firmly planted in cold, wet soil and their heads are exposed to sunlight. Plant low-growing annuals in front of them if you can to provide shade for the roots.
- Pick a spot that drains effectively. If your soil tends to be acidic, it is recommended to add some powdered lime to the surface.
- Mix liberal amounts of compost or well-rotted manure into the ground to a depth of two feet to create a rich soil. (Learn more about adding amendments to the soil and getting it ready for planting.)
- You should dig a beautiful, deep “compost trench” that is around 4 inches deep before planting.
- After digging the trench, use a pencil to cut holes, place the seeds inside, and then press down on the earth to compact it and block out any light.
- The seeds should be soaked in water for 24 hours prior to sowing. To hasten sprouting, nick the seeds with a nail file before planting. In a temperate climate, seeds don’t need to be soaked.
How to Grow Sweet Peas
- Depending on the soil temperature, germination after planting can take anywhere from 7 to 15 days.
- Fill in the trench gradually as the seedlings appear and develop. Hoe additional dirt toward them.
- Keep the soil wet. Summer rains may be plentiful. Sweet peas can have bud drop; if you stick your finger into the soil bed to its first joint and the soil is dry, water them at the soil level and do so in the morning.
- You won’t need to fertilize if you plant with a lot of compost and aged manure. Use high potash feeds if you do want to supplement the diet because nitrogen feeds promote excessive top development.
- Mulch well once plants are planted to keep the soil cool and moist. Unless the soil becomes dry, you might not need to water your sweet peas if you mulch.
- Pinch off the tops when plants are 6 inches tall, not sooner, as this will promote the production of side shoots too early.
Provide Supports
- When temperatures rise above 65°F, sweet peas will begin to fade since they like chilly days and nights.
- Sweet peas are true climbers, with the exception of the bush forms. Provide them with sufficient support for at least 6 feet. Some species can reach heights of nine or ten feet. A braided willow obelisk, bamboo poles in the tee-pee design, or a trellis are examples of other attractive supports. If you don’t have a fence or trellis, give them something to cling on, such chicken wire, bushy twigs, or brush.
- Give the plants a good start by tying the first few stems to the support; the rest will follow. When they reach a height of 4 to 8 inches, use your thumb and forefinger to pinch out the middle growing point. Plants will grow stronger as a result.
Picking Flowers
- Pick flowers frequently for bouquets so that the plant will focus its energy on producing additional blooms rather than seeds. Up until the first frosts, the more you pick, the more they produce.
- Allow a couple of the final blossoms to mature into seedpods when the leaves begin to lose their color. On a windowsill, dry them, and then keep in an envelope in a dry location to sow the following year.
From miniature bedding kinds ideal for pots and borders without support to 8-foot-plus scramblers, there are sweet pea varieties for every setting.
These decorative peas are native to Sicily, where they have flimsy stems and a powerful orange-jasmine-honey aroma. Modern hybrids feature larger blooms and stronger stalks.
However, some of these contemporary kinds, despite having larger blossoms and more fashionable colors, lack the earlier sweet peas’ perfume. Sweet pea ‘Cupani’ is still rightfully well-liked and simple to grow. It has bi-colored flowers with maroon upper petals and violet “wings.”
The decadently fragrant “America” is an antique from 1896. When its petals open, beautiful red and white wavy stripes are revealed.
Look for antiques like the Sicilian “Old Spice” collection. Shades of white, cream, pink, lavender, and purple can be seen in this strain’s blossoms.
A new cultivar with enormous, creamy-yellow blooms with violet shading called “April in Paris” is aromatic.
Although the ordinary sweet pea is an annual, Lathyrus latiflolius, a perennial broad-leaved everlasting pea, is not fragrant. These clambering plants have a height of up to 6 or 7 feet, are hardy to zone 5, require little care, and bloom continuously from year to year.
- An essential component of a late Victorian garden is the sweet pea. Because of their wide range of colors and aroma, Victorians adored sweet peas.
- When the dew is still on the flowers in the morning, gather them. Their best aroma is at this time.
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.
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.
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.