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.
How cold should it be for sweet peas?
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.
Can sweet peas survive a little 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 require protection from frost?
Peas can survive in temperatures as low as 28 degrees Fahrenheit (-2 C.) Peas and pea seedlings will be fine as long as temperatures don’t drop below this level.
Peas can withstand the cold in temperatures between 20 and 28 degrees F (-2 to -6 C), although they will experience some harm. (This is presuming that there is no insulating layer of snow when the cold strikes.)
The plants can survive temperatures as low as 10 degrees Fahrenheit (-15 degrees Celsius) or even 5 degrees Fahrenheit (-12 degrees Celsius) if snow has fallen and covered the peas.
The ideal temperature range for pea growth is between 50 and 70 degrees Fahrenheit (10 and 10 degrees Celsius) throughout the day and night, respectively. But even outside of these ranges, peas can still develop and bear fruit because these are the ideal conditions for their growth.
Folklore might suggest that you plant your peas by the middle of March, but it is always a good idea to consider your region’s climate and weather patterns before doing so.
Can sweet peas withstand UK frost?
Sweet Peas in the Cold Annual sweet peas can withstand frost. Therefore, if a “typical” nighttime frost in the range of -1 to -4 degrees centigrade is predicted, there is no need for concern.
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.
At what temperature do peas die?
Beans, cantaloupe, corn, cucumbers, eggplant, okra, peas, pepper, potatoes, sweet potatoes, squash, tomatoes, and watermelon would typically all perish in a frost (31-33 degrees F).
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.”
Can sweet peas still be planted in may?
Since most varieties of sweet peas won’t germinate in warm or hot weather, it’s never too cold to start a fresh crop. While certain plants are bred to thrive in hotter areas, the majority need to be planted when the earth is cool to the touch and between 40 and 50 degrees Fahrenheit. The ideal time to plant sweet peas in USDA planting zones 7 to 9 is in late October to mid-November, or even into December if there are no harsh frosts in the area. It is okay to plant them if the soil is still workable at that time.
Do peas get hurt by frost?
One of those wonderful crops that does best when planted in the winter is the pea (Pisum sativum). Peas may resist some frost and can be planted in late winter for an early spring harvest, despite not being the most cold-hardy of the popular winter crops. Peas don’t overwinter well in colder locations, unlike certain winter vegetables, although they are typically the first crop that may be grown once winter ends. According to the Old Farmer’s Almanac, you can grow them in the majority of USDA zones, from 2 through 9.
Pea plants do well in cooler climates, so a few light frosts or even a layer of snow that can really protect the plants won’t harm them. The seedlings and flower buds, however, can perish in a harsh cold.
How soon can peas be planted?
In many places, peas can also be grown in the fall. In locations where spring warms up too soon for optimal pea output, they can be sown in the late summer or early fall. Six to eight weeks before to the first date of fall frost, sow pea seeds.
Which vegetables can withstand frost?
Jim Myers, a plant breeder and researcher at Oregon State University, said that the brave gardener still has a chance to sow some cold-tolerant veggies for harvesting next spring. But don’t linger.
Winter planting is a dangerous endeavor, according to Myers. “If the winter is mild one year, it might work; if the winter is harsher the next, it might not. Depending on the crop, there is a strong chance that if you plant some cold-hardy veggies between mid-August and early October, you will reap the benefits in the spring. Farming, so the saying goes, is a gamble—some years more so than others.”
These hardy plants aren’t killed by the cold; it just pauses their growth. Growth rate doubles for every 18 degrees of temperature increase, however according to Myers, the rule only applies for air temperatures between 40 and 98 degrees. Vegetables that can withstand low temperatures can be planted between mid-August and early October with a chance of maturing by next spring if they make it through the winter in a vegetative condition without procreating.
Myers claims that spinach, Walla Walla sweet onion, garlic, leeks, rhubarb, rutabaga, broccoli, kohlrabi, kale, cabbage, chicory, Brussels sprouts, corn salad, arugula, fava beans, radish, mustard, Austrian winter pea, and turnip are the hardiest vegetables that can withstand heavy frost in air temperatures below 28.
Beets, spring market carrots, parsnip, lettuce, chard, pea, Chinese cabbage, endive, radicchio, cauliflower, parsley, and celery are semi-hardy vegetables that may tolerate light frost of air temperatures in the range of 28 to 32 degrees. The tops of beets, spring market carrots, and parsnips will wither while the roots can withstand colder weather.
According to Myers, vegetables with the anthocyanin pigment, which gives them a vivid red or purple color, are more resistant to rots brought on by winter rains. They consist of purple kale, Rosalind broccoli, and purple sprouting broccoli.
According to Myers, if you reside in a region of the state where snowfall is prolonged, the fluffy white stuff serves as an insulating mulch and heats the soil for these hardy plants.
No matter where you reside in Oregon, Myers said, “covering plants from the rain is pretty useful since some of the major difficulties we have in the winter are with rain rather than temperature.”
He advises using high or low tunnels, composed of metal hoops and translucent acrylic and available from greenhouse supply companies, to cover vegetables. Row coverings or cloches can also be used to protect plants. Use mulch produced from yard waste, cardboard, or newspaper to warm the soil.
Feast on shelled, luscious fava beans seasoned with salt and lemon juice before next March if you cross your fingers.