Sweet peas have been part of my garden for three years now—but for most of that time, you’d never guess it. Year after year, I planted them with high hopes, only to watch them struggle, barely producing the lush vines and fragrant blooms I had envisioned.
Sweet peas have a reputation for being both charming and finicky, and I quickly learned why. Year after year, I planted them with the best of intentions, only to end up with weak, struggling plants that never lived up to their full potential.
But last year, I was determined to get it right. I took the time to research what I had been doing wrong, made a few critical changes, and finally—sweet pea success!
So if you’ve struggled to grow sweet peas (or you’re planting them for the first time and want to skip the learning curve), this blog post is for you. I’m sharing the mistakes I made, the adjustments that turned everything around, and exactly how you can grow your best crop of sweet peas yet.
How Big is a Sweet Pea? Understanding the Growth and Size of this Iconic Garden Flower
Sweet peas are one of the most beloved annual flowers for cottage gardens and cutting gardens. Their beautiful, fragrant blooms on climbing vines evoke vintage charm and elegance. But just how big do sweet peas grow? In this in-depth article, we’ll explore the size range of these iconic climbers.
As a passionate gardener, I’ve grown sweet peas for many years and am always amazed by their rapid, vigorous growth when given proper care. By understanding the factors that influence their size you can choose appropriate sweet pea varieties for your space and ensure your plants reach their full potential.
Typical Height Range of Sweet Peas
Most standard sweet pea varieties grow to heights between 1-2 meters (3-6.5 feet) when supported properly and grown in ideal conditions. Here’s an overview of the height ranges:
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Standard sweet peas 1-2 m (3-6,5 ft)
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Dwarf or bushy sweet peas: Up to 45 cm (18 inches)
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Tall or climbing sweet peas: Over 2 m (6.5 ft)
So your typical sweet pea will reach 3-6.5 feet tall at maturity if given adequate support structure to climb up. More diminutive dwarf cultivars max out around 18 inches tall, while vigorous climbers can exceed 6.5 feet in height.
Sweet Pea Growth Habits
In addition to overall height, sweet peas exhibit variation in growth habit:
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Climbing – These utilize tendrils to grab onto trellises, fences, or other structures as they ascend upwards. Climbing vines are the most common type and yield long, straight stems ideal for cutting.
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Bush – Bush sweet peas have a more compact, mounding upright growth habit. They lack long vining stems and tend to stay much smaller overall than climbers.
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Semi-dwarf – Falling somewhere in the middle are semi-dwarf sweet peas. They may produce short vines but don’t require extensive vertical supports. Their height ranges from 60-90 cm (2-3 feet).
So factor in not just the expected mature height, but also the growth habit when selecting sweet pea varieties. Vigorous climbing types need adequate trellising while bushy ones are better for containers and small spaces.
What Factors Influence Sweet Pea Size?
Several key factors affect the ultimate size of sweet pea plants:
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Genetics – Some varieties are predisposed to larger sizes, while others are more compact. Choose ones suited for your available space.
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Growing conditions – Sweet peas grow larger in ideal environments with full sun, fertile soil, sufficient water, etc. Subpar conditions result in smaller plants.
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Structural supports – Climbing types only reach full size potential if grown vertically on adequately sized trellises, fences, etc.
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Pruning – Regularly pinching out tips encourages bushy, compact growth vs. letting vines grow freely.
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Container vs. ground – Plants grown in the ground can develop larger root systems and grow bigger than container-bound plants.
So with the right genetics, proper care and supports, sweet peas can become impressively sizable 1-2 meter blooming vines. But other situations may produce much more petite plants overall. Know your site’s conditions and provide appropriate assistances for vigorous climbers. More diminutive bush cultivars are better choices where space is limited.
What is the Size of Sweet Pea Flowers?
Now that we’ve explored the range of heights and habits of sweet pea plants themselves, what about the size of those charming, fragrant blooms?
Flower size can also vary considerably depending on the variety:
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Standard sweet peas – 1-2 inches (2.5-5 cm) in diameter
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Large-flowered cultivars – Up to 2.5 inches (6 cm) across
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Small-flowered heirlooms – As little as 1 inch (2.5 cm) wide
The sweet pea flowers arise on long peduncles and range from rounded, ruffled forms to more open blossoms with wavy, fringed petals. They come in a rainbow of colors like white, pink, burgundy, purple, lavender, red, blue, and bi-colors. But most commonly fall in the 1-2 inch diameter range.
Sweet Pea Vegetable Sizes
This article has focused on ornamental garden sweet peas (Lathyrus odoratus). But what about edible sugar snap peas and snow peas?
These vegetable garden favorites produce crisp, tasty pods that are eaten fresh off the vine. Their pod sizes are much larger than the flowers of ornamental sweet peas:
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Snow peas – 2-3 inches (5-7.5 cm) long
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Sugar snap peas – Around 3 inches (7.5 cm) in length
So vegetable sweet peas have significantly larger, fatter pods compared to the smaller individual blooms on ornamental sweet pea vines. Both make delightful additions to gardens and arrangements!
Ideal Support Structures for Maximum Growth
To achieve those impressively tall sweet pea vines of up to 2 meters or more, proper structural supports are key. Here are ideal trellising options:
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Metal or wooden obelisks – Place one at the end of each row or use multiple down a long run.
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Fences – Chain link, picket, wire garden fencing all work well. Position vines on one or both sides.
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Netting – Sturdy plastic mesh or nylon netting offers flexible support for vines to tangle through.
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Strings – Use twine, garden string, fishing line, etc. Tie horizontally between posts. Criss-crossing between vertical supports creates a web for vines to climb.
Position trellises, strings, or fencing so climbing vines will grow vertically 8 feet or taller. For bushy dwarf sweet peas, short 1-2 foot supports or rings may suffice to keep plants tidy and upright.
Maximizing Sweet Pea Size in Gardens & Containers
You can grow impressively large, flowering sweet pea vines by:
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Choosing vigorous, climber type varieties suited to your climate
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Providing tall, stable support structures like trellises
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Planting in fertile, well-draining soil in full sun
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Keeping plants consistently watered – they love moisture!
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Fertilizing regularly with balanced organic options
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Pinching out tips to encourage bushy growth
Even in containers, sweet peas can reach sizable proportions with proper care. Use large pots at least 12-24 inches wide. Add trellises or tepees for vertical climbing support. Keep pots well-watered and fertilized.
The Biggest Mistake Growers Make with Sweet Peas:
Now that I have a better understanding of how-to grow sweet peas, I can look back at my failed attempts and see so clearly what I was doing wrong.
Believe it or not, sweet peas are not difficult to grow from seed; they just tend to follow a different schedule than the more traditional cut flowers that most of us are accustomed to growing.
Allow me to explain…
The biggest mistake I made when trying to grow sweet peas was growing them too warm.
Like many beginner flower farmers, I assumed that all flowers prefer warmth—that seedlings should be pampered, kept cozy on heat mats, and protected from cold at all costs.
But sweet peas don’t just tolerate cold—they thrive in it.
Looking back, I can see where I went wrong:
- Starting seeds on a heat mat (bad idea—sweet peas germinate best in cool conditions)
- Waiting until after the last frost to transplant (by then, it was already too late)
- Not giving them enough time to establish before the heat of summer arrived
I thought I was being kind to my plants by shielding them from the cold—but in reality, I was holding them back.
So, how do you actually grow strong, healthy sweet peas? Let’s dive in…
Why Grow Sweet Peas?
I was first drawn to sweet peas because of their whimsical climbing habit. I imagined them adding vertical interest to my cutting garden, their delicate tendrils wrapping around trellises, their ruffled petals swaying in the breeze.
But after growing them (with varying degrees of success), I fell in love for an entirely different reason—their scent.
The fragrance of sweet peas is unlike anything else in the garden—soft, nostalgic, and completely intoxicating. And that alone kept me coming back, season after season, determined to figure out what I was doing wrong.
How to grow sweet peas: tips from a sweet pea flower farmer
FAQ
What size is a sweet pea?
In the wild plant the flowers are purple, 2–3.5 cm (3⁄4–11⁄2 in) broad; they are larger and highly variable in color in the many cultivars. Flowers are usually strongly scented. The annual species, L. odoratus, may be confused with the everlasting pea, L.
Do sweet pea flowers need to be trellised?
Because Sweet Peas are vining, they need support to grow up and flower. Many types of structures can work such as a trellis, supports with mesh or twine, or fences. They need a structure that is well anchored in the ground to support the weight of the vines.
What size pots do sweet peas need?
Sweet Peas have a large root system and will need a minimum container of 20 litres providing 7 litres per plant for Spencers and 5 for Old Fashioned. Keep well-watered with good drainage and water every day it does not rain.
What is a sweet pea?
Sweet pea (Lathyrus odoratus) is a climbing, flowering, sweet-smelling annual in the legume genus. Originating in the southwest of Italy and the islands of the Mediterranean, sweet pea has been used in gardens since the 17th century. Sweet peas lend a cottage feel to gardens.
How tall does a sweet pea grow?
It is an annual climbing plant, growing to a height of 1–2 metres (3 ft 3 in – 6 ft 7 in), where suitable support is available. The leaves are pinnate with two leaflets and a terminal tendril, which twines around supporting plants and structures, helping the sweet pea to climb.
Is a sweet pea a climbing plant?
The sweet pea, Lathyrus odoratus, is a flowering plant in the genus Lathyrus in the family Fabaceae (legumes), native to Sicily, southern Italy and the Aegean Islands. It is an annual climbing plant, growing to a height of 1–2 metres (3 ft 3 in – 6 ft 7 in), where suitable support is available.
What does a sweet pea look like?
Sweet pea flowers resemble fringed butterflies, while their sturdy stems appear folded. Their fragrance is sweet, like a blend of honey and orange blossoms. Sweet peas grow best from seeds, but if you don’t have any seeds and still want to make more plants, you can use seedling cuttings.
Are sweet peas easy to grow?
The ornamental sweet pea (Lathyrus odoratus), which is brightly colored and smells nice, is a favorite plant for casual cottage gardens and is easy to grow. Native to the Mediterranean, these plants do best in full sun and moist, rich, slightly alkaline soil during the growing season. For flowering, bone or blood meal amendments are often helpful.
Are sweet peas edible?
Despite having “pea” in their name, they are not edible and are toxic to humans and pets. Sweet peas are a beloved garden flower known for their vibrant colors, sweet fragrance, and climbing growth habit But just how big do these plants get?