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.
When may I plant sweet peas away from the UK?
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. utilize a compost that is good, peat-free, and has a slow-release fertilizer 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 greenhouse 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 meters. 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?
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.
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 they withstand frost?
I adore annual sweet peas and believe that they are the most alluring and unforgettable garden flowers because of their beautiful scent, ruffled, winged blossoms, and treasure trove of radiant hues. These fluted beauties are excellent for cutting, and a tiny bouquet of them will fill a room with a mouthwatering aroma that makes me think of orange blossoms and honey. Sweet peas’ delicate, alluring scent is one of nature’s best-kept secrets; it has never been artificially imitated and is never overbearing or cloying.
There are now a large number of options available in a wide range of colors, from the most delicate sweet pastels to rich, vivid deep hues, including stripes and bicolors. You have a choice of classic, tall, quickly-growing vining sweet peas, non-climbing, dwarf kinds for beds and borders, and variants that cascade 8 to 10 inches in containers. All will beautify and fill the garden with a divine aroma in the spring and summer.
Sweet pea horticulture has a lengthy and fascinating history. On an island off the coast of Sicily in 1699, Father Cupani, a botanizing monk, was the first to gather sweet peas in the wild. Eckford, an Englishman, started hybridizing and selecting sweet peas in the 19th century, bringing in larger varieties in a wider spectrum of hues. These “grandifloras,” which are now referred to as “old-fashioned” or “heirloom,” were highly praised as cut flowers.
In this time, cultivars that were more suited to American garden conditions were created by American seed producers who were growing sweet pea seeds for export to the English market and for American seed catalogs. The coastal region near Lompoc, California, which is chilly, moderate, and windy, is perfect for growing sweet peas because the climate prevents the usual bee visitors from visiting the blooms, preventing cross-pollination and allowing for the preservation of exceptionally pure seed strains. Today, that region, together with England, New Zealand, and Tasmania, continue to supply a large portion of the world’s sweet pea seed.
You will find growing sweet peas to be quite gratifying if you follow the right guidelines and timing for planting. Sadly, sweet peas have a reputation for being challenging to produce, especially in the Midwest and Southeast. However, after speaking with successful sweet pea gardeners around the nation for many years, I am confident that sweet peas can thrive everywhere in the nation. Their beauty and smell are definitely worth the effort even in the rare places where they are more difficult to grow. Knowing when to plant the seeds and how to take care of sweet peas effectively are crucial.
When To Plant Sweet Pea Seeds
Sweet peas can be planted in the fall and again in the spring in regions with warm winters that experience prolonged rainy winters and cold summers, such as the Pacific Northwest. Sue, a gardener from Seattle and the creator of our website, plants seeds in April or May for “armfuls of blossoms” through September.
Plant seeds as soon as the ground is workable in rich, well-drained soil in locations with temperate winters, such as the mid-Atlantic states, which experience humid summers and early, unexpected summer heat. Don’t wait until you plant other annual flowers like sunflowers or cosmos or until the date of your last frost (sweet peas may withstand minor frosts). Your sweet peas won’t be developed enough to withstand the hot temperatures of early summer. If it doesn’t rain, make sure to water your sweet pea plants because they require constant moisture.
Nancy Hammer, a market gardener in Virginia, starts seeds indoors in jumbo packs or 4 inch pots in late March so that they can be planted outdoors as soon as they have two or three pairs of leaves. This allows her to get a head start on the season and prepare for the unpredictability of spring weather. In early to mid April, she also plants seeds straight in the ground. In this manner, she will be ready with healthy seedlings regardless of whether it is chilly and rainy well into spring or if sudden hot weather arrives.
Both Susan Keating in Maine and Jay Leshinsky in Vermont wait until the spring soil can be easily handled before planting, often in late April through mid May, in locations with extremely harsh winters like New England where the earth freezes hard and heaves. Additionally, they get a head start by starting seeds indoors a month to six weeks in advance and planting them outside as soon as the weather allows through May. In either case, keep in mind that sweet peas are unaffected by late, mild frosts. Sweet peas planted in the ground in northern regions in April and May will blossom fully in late summer and continue to do so virtually until the first frost. If the summers are particularly hot, choose a location where the vines will receive some afternoon shade and water if it doesn’t rain.
Do peas survive frost in the UK?
Plant the seedlings in their final locations outside after a week of hardening off. Pea plants may withstand frosts down to minus 3C with little to no harm if they are started indoors in pots and then hardened off for about a week.
When should sweet peas be planted?
Sweet peas can be grown at any time between October and March and are simple to grow from seed. Sweet peas are hardy annuals that only require protection from severe frosts; planting them in the spring after being sown in October or November will give them a head start and the chance to develop incredibly robust root systems.
Monty Don writes in his monthly blog, “By seeding sweet peas in October-November, you will get bigger plants with a stronger root system that should provide blossoms next spring earlier and last longer” (opens in new tab).
The fact that sweet peas are hungry and thirsty plants should also be kept in mind when growing them. As a result, it’s critical to fertilize the soil and give them regular irrigation, about once a week. Monty Don says, “Make sure you add heaps of organic materials, if only to act as a reservoir to hold moisture for them.”
When can peas be planted outside? at what temperature?
Peas should be planted in the very early spring as soon as your garden soil is workable because they can withstand frost and grow best in chilly soil. Optimum soil temperature for pea germination is 40 to 70 F.
Are sweet peas tough?
Sweet peas are a robust annual, so they can withstand cold temperatures, including a light frost if it is below freezing. They can withstand a regular cold down to about -4 degrees and are tougher than they appear. Sweet peas only need to be protected, such as with a fleece, if a heavy frost or extended period of low temperatures is predicted.
Do not wait until it is too late to grow sweet peas because they are hardy. Sweet peas can be sown beginning in March. The sweet peas grow best when tied to a structure, like a trellis or an obelisk.
Remove the tendrils and don’t allow them grow unchecked if you want straight stems and sweet peas that grow up the frame rather than a tangled clump. Why? See how to give sweet peas straight stems.
Don’t let the seed head form; keep plucking sweet peas. Check at the picture where the seed pod is ringed in red if you have any questions about seed pods. The sweet pea will reward you with increasingly more blossoms if you remove all seed heads as they develop.
How to pinch out sweet peas
As soon as the ground can be handled, sweet pea seeds can be planted immediately into thoroughly loosened soil.
According to Garden Know How, pea seedlings should be spaced five to six inches (12.5 to 15 cm) apart once they have sprouted to a height of three to four inches.
Wait until sweet peas are between four and eight inches tall before pinching them out.
Then, using your nail as a blade, cut off the growing tip that is between your forefinger and thumbnail.