One of the best plants for cutting, sweet peas (officially known as Lathyrus odoratus) offer tempting colours and aroma for spring and early summer bouquets. The tiny flowers emit a grape-like fragrance into the air and come in a variety of beautiful colours. We enlisted the assistance of Barb Pierson, our nursery manager, to provide some guidance for individuals who have never grown Sweet Peas in a garden or a container pot. Any beginner or green thumb can benefit from a plentiful supply of these lovely flowers thanks to her advice.
Why do people grow Sweet Peas?
Sweet peas are cultivated for their lovely, ruffled blossoms, which come in pastel, blue, and bicolor hues. They are a beautiful cut flower since many types have scented blooms. The cultivation and breeding of sweet peas for both the home grower and the florist industry has a long history.
How do I go about growing Sweet Peas?
Sweet peas can be grown from seed that is treated before sowing or, more conveniently, from a starting plant. At White Flower Farm, we plant three seeds in each pot to create three Sweet Pea vines.
Where do I plant them and when?
In the northern half of the US, sweet peas flourish in the full sun. They can benefit from afternoon shade in the South. They are planted as early as possible in the spring since they prefer mild temperatures and cool roots. Newly planted seedlings will not be harmed by a mild cold. They can be sown in the fall and cultivated through the winter and early spring in highly warm climates. Compost should be added to the soil, and the area should be well-drained for optimal results. Sweet peas can be successfully grown in raised beds.
Do they need any special care while they are growing?
Sweet peas require support to grow and flower because they are climbing plants. Many other kinds of structures, like a trellis, supports made of mesh or wire, or fences, can be used. To sustain the weight of the vines, they require a sturdy framework that is firmly planted in the ground. The vegetation will develop tendrils that encircle the support you offer.
Since they like nutrient-rich soil, adding compost at planting time is advised. Mulching Sweet Peas will keep the roots cool and help them retain moisture as they grow.
Pinch the growth tips by one after the plants have reached a height of around six to encourage branching and the development of extra flowering stems.
What are the most common mistakes that people make with Sweet Peas?
- planting them in the middle of the summer They dislike the heat and won’t blossom as frequently.
- not offering assistance when planting. Once the plants have begun to grow, it is challenging to instal your trellis or support.
- Lack of compost or fertiliser will cause weak plants and fewer flowers in poor soil.
- If Sweet Peas are planted too closely together without being thinned out, powdery mildew can grow and crowding lowers bloom production.
Do Sweet Peas produce pods that you can eat like the ones you find in the grocery store?
Despite having the appearance of snap pea pods, the seed pods are not edible. The pods and seeds can be saved in order to grow plants the following year. Remember that the plants that the seeds may grow may not be the same hue as the parent plant.
Will the plants come back again next year?
The plants are typically not winter hardy in most areas. They are replanted with new seed and plants even in warm climates to produce the most flowers and have robust development.
When do they bloom? Are there tips for getting extra blossoms?
Sweet peas will begin to blossom 4 to 6 weeks after they begin to show apparent vining. Whether or not the plants have been pulled back will affect the timing of the bloom. Although pinching may slightly limit growth, it will result in bushier plants with more flowers. In the spring and early summer, sweet peas will grow and bloom more quickly as the days lengthen. Compost or old dry manure can aid to supply nutrients for the growth of huge, many blooms. A fertiliser with a phosphorus to nitrogen ratio greater than one can also increase flower production.
What is the process for cutting the blooms?
Cut the blossoms early in the day to prevent the sun from drying them off. For your vase, select newly opened flowers with the longest stems. Just the side flowering stems of the plant should be clipped; leave the main stem alone.
Why should I get my Sweet Peas from White Flower Farm?
No seed treatment or waiting for germination is necessary because our plants are grown in our greenhouses in the spring and supplied to you at the ideal time for planting in your region. Our sweet peas arrive completely rooted and ready to plant in the ground in 4 pots, each containing 3 seedlings. You can avoid the time and hassle of starting sweet peas from seed by doing this. The quickest method to enjoy these beautiful flowers outdoors and in vases within your house is to purchase and plant our Sweet Pea seedlings.
Sweet peas can be planted outside when?
Sweet peas should be planted in a well-drained but moisture-retentive soil in an open, sunny location. Sweet peas are ideal for container gardening. utilise a compost that is good, peat-free, and has a slow-release fertiliser added in.
How to sow sweet peas
From seeds, sweet peas are simple to grow in the spring or autumn. If you are planting in the fall, make sure you have space for them to grow until spring in a frost-free location.
Sweet pea seeds sprout fairly quickly. However, by nicking the seed coat with a knife and avoiding the “eye” region, you can encourage germination. Either plant seed in trays, root trainers, or 9cm pots (3 to a pot). Place the seed in a cold frame or glasshouse after sowing it in high-quality, peat-free compost.
View Monty Don’s instructional video on how to cultivate sweet peas from seed:
Planting out sweet peas
Once all risk of frost has passed, you can start planting your sweet peas in late May. Put them outside throughout the day and bring them inside at night to harden them off before planting. When young sweet pea plants are around 10 cm tall, pinch out the tips to promote bushy growth.
In the spring, you can purchase sweet pea plug plants. Under a support, such as a wigwam made of bamboo canes, plant them in rich soil. The average sweet pea will reach a height of 2 metres. Until they have a healthy growth, water them well. Don’t worry about separating individual plants; simply space sweet pea plugs or pots about 20 cm apart.
Watch Monty as he demonstrates how to put out store-bought plants while planting sweet peas. Find out the advantages of giving them a nice drink after planting as well as why it is best to plant them out just once the soil has warmed up:
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 categorised 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.
When do you sow your peas?
Nothing compares to the delightful flavour of peas straight from the garden in terms of sweetness. They are fresh candies from nature! One of the earliest crops of the year, peas are planted as soon as the land can be worked, even if snow follows. See our growing advice for peas, from planting to harvesting!
About Peas
Peas are incredibly simple to raise, however they only have a very short growing season. It’s crucial to plant them in the springtime early enough for them to mature while the temperature is still cool. (This refers to planting in most of the United States and Canada in February, March, or April.) In warmer areas, they can also be cultivated as an autumn or winter crop.
Enjoy the flavour of peas as soon as you can because they don’t keep fresh for very long after harvest. The taste of the peas you get in grocery shops, which are frequently starchy, is incomparable to garden-fresh peas.
Most garden and culinary requirements can be met by three types of peas:
- The seeds (peas) of sweet peas, also known as garden peas or English peas (Pisum sativum ssp. sativum), are extracted from inedible pods.
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.
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 colour 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 colours, including bicolored varieties. However, the perennial varieties do come in some uncommon colours, 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 centres 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 centres 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 fertiliser, 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 fertiliser, 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 encourages strong 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 maximise 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 glasshouse 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.