QUESTION: I heard some other gardening radio
program people saying that sweet peas are poisonous to eat? My
sisters and I ate them all the time with no ill effects. What
ANSWER: Some folks just go crazy with half-truths about which
plants are poisonous and which are not. Our favorite source of
reliable plant information at: http://www.ces.ncsu.edu/depts/hort/consumer/poison/Lathysp.htm
gives the following information about sweet peas:
"EDIBLE PARTS: Peas and very young pods
HARVEST TIME: Only collect peas and young pods from areas you
know have NOT been treated with
pesticides. Collect young pods in early summer and peas slightly
SAFE HANDLING PROCEDURES: Soak peas and young pods in warm water
to remove dirt and debris. Do not use dish detergent or any type
of sanitizer. These products can leave a residue. Boil in salted
a dash of sugar. Cook until bright green and tender. Or, stir
fry young pods with other vegetables .
SOURCE: Crowhurst, A. The Weed Cookbook. Lancer Books, New York.
With this being said, confusion is understandable when one reads
from another source: "Although garden peas, (Pisum sativum)
such as English peas, edible podded peas and snow peas are edible,
sweet peas (Lathyrus odoratus) are poisonous - especially the
flowers and seeds." This means that only the mature, hardened
seed is poisonous if ingested.
by the National Garden Bureau
North America’s enchantment with sweet peas goes back more
than a century. In the 1930’s box cars of sweet pea seeds
were shipped from California producers to their customers east
of the Rockies. The love of this fragrant garden climber was widespread
in North America from farms of the plains to country gardens in
the northeastern United States.
English gardeners call sweet peas "the Queen of Annuals."
These charming annuals are unique among garden flowers with their
vivid colors, fragrance, and length of bloom in the garden. The
flowers have an air of romance about them in both their scent
and appearance. Sweet peas’ fragrance is sensuous, a captivating
blend of honey and orange blossom, with an intensity that varies
from one cultivar to another. The ruffled blooms look like little
butterflies all aflutter. Sweet peas offer one of the widest color
ranges in the plant kingdom, including crimson reds, navy blues,
pastel lavenders, pinks, and the purest whites. These colors are
found as solid colors, bicolors, and streaked or flaked flowers.
Put it all together - fragrance and color - in a climbing plant
with voluptuous clusters of flowers and it becomes obvious why
sweet peas are such a favorite among gardeners and non-gardeners
alike. The fact that they are long-lasting cut flowers is the
icing on the cake. Several stems in a plain vase make a lovely
Sweet peas can adapt to any garden style. They are excellent
in a cutting garden, ensuring a bounty of flowers to enjoy indoors.
The loose, billowing form of bush varieties makes them a natural
in a cottage garden. Sweet peas can take on a more formal or casual
look when they are growing up a support. Give them a trellis or
fence - white picket, post and rail, or even chain link - sweet
peas have an informal panache. Yet, train them on a tuteur and
they exhibit all the class necessary for any formal garden. Arbors
and trellises - available in so many styles - are perfect foils
for sweet peas’ adaptability.
Finding the right season to grow sweet peas will enable any gardener
to enjoy their scented blooms. Sweet peas can take frost as they
develop. So in North America, gardeners can enjoy these bloomers
from early spring onward. Ideally, gardeners want to take full
advantage of spring color by sowing seed in the fall in southern
states and early spring in northern regions. With protection from
intense afternoon heat and proper mulching, the blooming season
of sweet peas can be greatly extended.
Interestingly, the origin of the sweet pea in the wild has been
greatly disputed. The first written record appeared in 1695. Francisco
Cupani, a member of the order of St. Francis, noted seeing sweet
peas in Sicily. There is no documentation of whether the sighting
was in the wild or in the botanical garden in the village of Misilmeri
(near Palermo) that was under his charge. It was not until 1699
that Cupani passed on the seeds of the enticingly fragrant, small
bicolor flowers (blue and purple) to Dr. Casper Commelin, a botanist
at the medical school in Amsterdam. In 1701, Commelin published
an article on sweet peas, which included the first botanical illustration.
Historians presume that Cupani also sent seeds to Dr. Robert
Uvedale - a teacher and aficionado of unusual and new plants -
in Middlesex, England at the same time as he sent them to Amsterdam.
This assumption is based on a herbarium specimen that Dr. Leonard
Plukenet made in 1700, noting the plant’s origin as Dr.
Although the exact origin of the sweet pea is uncertain, the
original Cupani variety, a bicolor with purple upper petal and
deep blue winged petals, is available to gardeners still under
the name Cupani! Origins aside, a hundred years after their "discovery"
there were only six colors available in Europe until the mid 1800’s.
Finally, near the close of the 19th century, sales took off. In
England, Henry Eckford, who hybridized and selected sweet peas
for their best characteristics, introduced the Grandifloras, which
revolutionized sweet peas. They were larger, with more color choices
and had a lovelier form than the typical sweet pea. Twenty-three
Eckford varieties are still available to gardeners today from
Bodger Seeds in California who sells them to seed packet companies
as separate colors and in fashionable mixes. Theme blends of these
striking flowers include all blue shades - 'Ocean Foam' and 'Jewels
of Albion;' red and pink blends- 'Red Rover' and 'Queen of Hearts;'
and deep rich combinations - 'Queen of the Night.'
In 1901, Silas Cole, head gardener to the Earl of Spencer, found
a natural mutation in the garden under his care, which he named
Spencer’s. The Spencer type became very popular because
of its ruffled standard (the upper petal) and long wing (lower
petals) that resulted in larger, more flamboyant blooms. They
were late flowering varieties, which did not matter when grown
in the cool English climate. Spencer types were also improved
for the number of flowers produced per stem and were thus called
"multiflora." There are many Spencer sweet pea colors
available for gardeners today. The Spencer flowers remain very
popular in England and Europe.
Sweet pea 'Streamer's Mix'
'Streamer's Mix' sweet pea
There are many American seed companies that contributed to the
advancement of sweet peas. Three American bred varieties from
the early twentieth century remain popular today and are still
in commerce. They are the long vine 'Royal' separate colors and
‘Royal Family Mix,' the shorter vine 'Knee-Hi Mix' and the
very compact 'Little Sweetheart Mix.' California breeding of sweet
peas has focused on developing extremely early flowering and non-tendril
types. Mr. Yosh Arimitsu of Bodger Seeds Ltd. selected a series
of sweet peas to be extremely early under long day or short day
growing conditions, to have flower stems longer than 17 inches,
and to produce extra large flowers on stems with 5 to 7 flowers.
There are numerous improved qualities in the 'Elegance' series
bred by Bodger Seeds Ltd.
There has also been work done in non-tendril sweet peas. Typically,
sweet peas have two leaves and two tendrils that cling and assist
vines as they climb toward the sky. In non-tendril lines, the
tendrils develop into true leaves and, thus, plants have four
leaves per stem. Non-tendril varieties have shorter vines and
are excellent for bedding use. Mr. David Lemon did the original
non-tendril work at Denholm Seeds with the creation of 'Snoopea
Mix' and later at Bodger Seeds with 'Explorer Mix,' winner of
the RHS Award of Garden Merit.
Compact container sweet peas have a long history. 'Cupid' varieties
were popular in the early 1900’s and, at one time, greater
than 30 varieties were available. With the growth of interest
in container gardening, 'Cupid' lines have again become favorites
of North American gardeners. ‘Cupids’ can be grown
in window boxes, hanging baskets and containers. In recent years,
New Zealand has also been a source of new sweet pea varieties,
especially the breeding of Dr. Keith Hammett. He made great strides
in the development of new color patterns, short day flowering,
and a focus on fragrance. 'Streamers Mix' and 'Saltwater Taffy'
are Hammett's creations containing all striped varieties in a
single mix. 'Streamers Mix' is composed of many striped varieties,
including chocolate/white, blue/white, orange/white, red/white
stripes and shades between.
There is a great deal of variation in the fragrance and intensity
of smell in sweet peas. Since the odor that our noses detect is
from a complex combination of volatile chemicals produced within
the flowers, the strength of fragrance of a sweet pea variety
can change due to a number of factors, such as rain, high temperatures,
time of day and the age of the flower.
Certainly, some of the older varieties from the Eckford lines
are the most reliably fragrant sweet peas. They are blended together
in mixtures called 'Old Spice Mix' and 'Perfume Delight.' Dr.
Hammett has begun work on a number of selections that are especially
fragrant. These varieties are available with names like 'High
Scent,' 'April in Paris' and 'Renaissance.'
The moniker, "sweet pea," was supposedly first used
by the poet Keats in the early 1800s. Both English and North Americans
use the common name, "sweet pea."
This text has focused on Lathyrus odoratus, common name sweet
pea, but there are a number of other Lathyrus species worth mentioning.
They include the perennial Lathyrus latifolius, available in four
colors and a mix. This cold hardy perennial is suitable to USDA
temperature Zone 5. Lathyrus sativus produces lovely small gentian
blue flowers, while Lathyrus chloranthus has yellow flowers. This
last species has been used, thus far unsuccessfully, in inter-species
breeding attempts to bring the elusive yellow flower into the
commercial L. odoratus. All three of these species mentioned above
are commercially available in North America. Within the genus
Lathyrus, there are 110 species and innumerable cultivars. In
broad terms, the genus is commonly known as vetchling or wild
pea. It is in the Leguminosae (a.k.a. Fabaceae) or Legume family.
Other legumes include garden peas, acacia, beans, mimosa, redbud,
soybeans, wisteria, and clover.
With the growing interest in edible flowers, it is very important
to be specific with the name. Although garden peas, (Pisum sativum)
such as English peas, edible podded peas and snow peas are edible,
sweet peas (Lathyrus odoratus) are poisonous - especially the
flowers and seeds.
There are four ways to classify sweet peas. They are habit, flower
form, fragrance, or day length response. Plant habit can be climbing;
tendrils wind around a support and can grow 6 to 10 feet depending
upon the growing conditions and cultivar. The plant habit can
be compact reaching only 8 to 24 inches tall and needing no support.
Avid gardeners select the site first, and then determine the best
variety with the desired habit for that site or container.
The sweet pea flower form can be single, double, or semi-double.
The flower diagram shows the anatomical names of the flower parts.
The flowers can be fragrant. If this is important, look for those
that are labeled fragrant.
Many plants initiate buds or flowers under certain day length.
These are called short day or long day flowering plants. Most
sweet pea cultivars need lengthening days to initiate buds and
bloom. This means growing sweet pea plants after March 21 as day
length increases. In the southern regions of North America, sowing
sweet peas in the fall requires cultivars that are "short
day flowering" due to the shorter day length of fall and
winter. There are cultivars that fit this cultural requirement
such as 'Elegance' series.
STARTING SWEET PEAS FROM SEED
Timing by Region
Sweet peas are one of the easiest flowering annuals to start
from seed. Sweet peas are commonly direct seeded in the garden.
Give them a site with full to partial sun and deep, rich, loamy,
moist but well-drained soil. Add plenty of organic matter (compost,
well-rotted manure, leaf mold, or humus) to enrich the soil and
make it more friable.
Sweet pea 'Pastel Sunset'
'Pastel Sunset' sweet pea
Sweet peas are most successful when they are started at times
with cooler temperatures. Each region has its own unique "season"
for growing sweet peas. In western North America, sweet pea seeds
should be sown from August forward to maximize winter and spring
flowering. Although sweet peas can be killed back by hard freezes,
they are reasonably cold hardy and can take frost without much
damage to plants. Cooler night temperatures extend the enjoyment
of sweet pea flowers in the west into the summer months.
In the drier plains states, sweet peas can be started early
indoors for transplanting or sown directly after the harshest
weather has passed. Cut flower growers in Colorado have successfully
grown sweet peas through high summer temperatures by mulching
heavily as plants mature and weather heats up.
In the south, sow seed in November or December for early spring
fresh cut flowers. In the mid-west and northeast non-coastal areas,
sow seed indoors in February and transplant into the garden when
the ground thaws. Alternatively, seed can be sown directly into
prepared garden soil in April. Finally, the coastal areas of the
northeast are excellent areas to grow sweet peas for spring use.
Sweet peas will need about 50 days of cool temperatures (under
60º F) to bloom gloriously in your garden. Sweet pea seed
has a hard, water insoluble seed coat. There is no evidence that
soaking sweet peas will increase germination. Nicking the outside
coating of a sweet pea seed will allow rapid hydration of seeds
and does both speed and increase germination. Nicking can be easily
accomplished by using a nail clipper to score the sweet pea seed
coat. Sweet pea seed will germinate in soil at temperatures of
55º to 65º F or 13º to 18º C.
Plant seeds in holes that are about two inches (two knuckles)
deep. Drop two to four seeds per hole, with holes spaced four
to six inches apart. Water thoroughly and keep soil moist until
seeds have sprouted. Expect germination in about 10 to 21 days.
Once the seedlings are growing, water regularly to promote strong,
healthy growth. When the seedlings are three to four inches high,
thin them out, leaving the most vigorous-looking plants four to
six inches apart. Sowing seeds each week over several weeks will
further extend the time you get to enjoy your sweet peas. Grow
them in peat pots or four-inch plastic pots filled with a soil
free seed-starting mix. Sow two or three seeds per pot - pushing
each an inch down into the potting mix. Cover with mix, water,
and put the pots in a cool, dark place. After about 10 days, keep
an eye out for new shoots emerging above the soil. At that point,
bring the plants out into the light. Keep them in a cool place
(below 55°F.); if they are coddled in a warm room, they won’t
be tough enough to transplant outdoors without a lengthy hardening
off period. When the seedlings have two sets of real leaves, thin
to one plant per pot. Transplant into the garden about a month
before the last frost date, as soon as the soil is workable -
the shoots are tough and won’t be bothered by light frost.
Allow 6 inches between climbing varieties, 12 inches between dwarf
When planting tall, long vine sweet peas, it’s best to
place the stake or support in the ground at the same time as the
seed or transplants to avoid damaging the roots. Trellises are
the most common supports, yet there are other climbing options.
Bird netting strung between two stakes, string, twine, or fishing
line hung from the top of a split rail fence, a bamboo teepee,
brush stakes - all are good verticals for sweet peas to climb.
Unless the support is up against a wall, sow seeds on all sides,
producing an eye-catching array of blooms that can be seen from
all directions. Once the plants have been thinned, mulch them
well; a four- to six-inch layer of organic mulch will keep the
roots cool and extend the growing season.
Do not over fertilize or you’ll wind up with very deep
green leaves but few flowers. A balanced 20-20-20 slow release
fertilizer blended into the soil at planting time works fine for
the initial plant development. Alternatively, organic fertilizers
are also excellent for sweet peas. Additional mulching with composted
manure will help retain soil moisture and provide nutrients for
strong plant growth and flowering.
If blooms are not cut regularly, deadhead the plant as soon
as flowers fade. Allowing the plant to produce seedpods will reduce
overall flower production. Removing spent blooms will ensure more
The first challenge for sweet peas, like other direct-sown seeds,
is to avoid being plucked out of the ground by voracious birds,
mice, squirrels, and other critters. As seedlings, sweet peas
are vulnerable to birds, slugs, and snails, especially if fall-planted
in a warm climate. Preventative measures often deter a problem
before it has a chance to get started. Follow these guidelines
for healthier plants. Plant sweet peas in an area that gets good
air circulation. Water early in the day so the leaves are dry
by nightfall; wet leaves are a magnet for fungus. Think of sweet
peas like food crops. Rotate planting areas so that the sweet
peas are grown in the same space once every four years. Don’t
grow sweet peas where other legumes are growing or grew last year.
Legumes include garden peas, beans of all types, peanuts, and
How to Grow From Purchased Plants
You may find sweet peas sold as plants particularly at some
specialty nurseries or garden centers. There may be ready-made
container plantings of sweet peas - an instant garden. Sweet peas
need tender care when transplanted, so look for plants in individual
earth friendly pots or peat pots. The larger the pot, the better.
Right before planting, snip off any flowers or flower buds. This
is the time to get the roots well established so they can support
the growing plant’s needs. Even though you sacrifice early
blooms, you’ll be rewarded with bigger plants with an abundance
of larger flowers.
Plant into prepared garden soil or a container. With transplants,
it’s even more important to plant the support before digging
the plant in to keep the precious roots out of harm’s way.
Try to keep the root ball together. Plant it at the same depth
as it was originally growing. Lightly firm the soil around it
and water. Wait a week to ten days before mulching. Be sure to
keep the mulch at least an inch away from the stem of the plant
until plants are well established. Otherwise you could smother
the stem or be likely to encourage insects, pests, and diseases.
The introduction of 'Cupid' - the first dwarf sweet pea - at
the turn of the 19th century brought sweet peas into the realm
of containers. Their diminutive size suits hanging baskets, window
boxes, pots, urns, and all other sorts of containers. There are
many dwarf sweet pea types available from mail order catalogs
or in seed packets purchased at stores. Climbing sweet peas also
make great container plants. Instead of sowing one or two seeds
at the center of the container, make a circle of seeds - spaced
a couple of inches apart - an inch in from the rim of the pot.
In the limited space of a container, it’s easiest to plant
the support and then sow the seeds around it. For larger containers,
tomato cages are perfect supports; the legs can be pushed into
the potting mix. Since sweet pea shoots aren’t bothered
by frost, you can set a container of sweet peas out in the garden
in early spring (at the same time you’d plant seeds outside.)
Bring the Outdoors In - Container Plants
When the first flowers appear, start cutting flowering stems
for indoor bouquets. In addition to adding the sweet perfume in
the house, you’re encouraging the plant to produce more
flowers. Cut stems every other day, early in the morning when
they are the freshest. For climbing varieties, thinning lateral
shoots that start at the base of leaves will reduce vegetative
growth, increase flower production, and encourage better air circulation
around the plant.
The stems will look full when you first arrange them and the
remaining buds will open as the first blooms fade. Be sure to
remove any leaves that are below water level in the vase. A bouquet
of sweet peas can easily last a week indoors if you cut off 1/4
to ½ inch at the base of each stem and change the water
This material is reprinted courtesy of The National Garden Bureau.
Cathy Wilkinson Barash is the author of this fact sheet.