What Are Sweet Peas and Why Grow Them?
Sweet peas (Lathyrus odoratus) are beloved annual climbing plants renowned for their intensely fragrant, delicate, and colourful flowers. They are a favourite for cut flower arrangements, garden borders, and scrambling over supports, offering a delightful scent that fills the air during their blooming season.
- Intensely fragrant, delicate blooms.
- Ideal for cut flowers and garden displays.
- Annual climbing plants requiring support.
- Attract pollinators to the garden.
Beyond their aesthetic appeal and delightful perfume, sweet peas serve a valuable ecological role by attracting bees and other pollinators to your garden. Their climbing habit makes them versatile, suitable for covering trellises, obelisks, fences, or even grown as a ground cover in some instances. The sheer diversity of colours and forms available means there is a sweet pea to suit nearly every garden palette and preference, from soft pastels to vibrant hues.
When considering ornamental plants, sweet peas often stand out. Unlike some other garden flowers such as petunias or marigolds which offer visual appeal, sweet peas combine striking beauty with an unparalleled fragrance. They are relatively straightforward to cultivate, provided they are given the right conditions. Their unique charm lies in their ephemeral nature, blooming profusely for a significant period but requiring a full growing season.
The appeal of sweet peas is rooted in their ability to evoke nostalgia and create a sense of abundance. Their ruffled petals and climbing tendrils add a whimsical, romantic feel to any space. For those seeking to introduce more natural scents into their outdoor living areas, or simply wanting to cultivate flowers that are both beautiful and fragrant, sweet peas present a compelling choice.
Cultivating Your Sweet Peas: Planting and Care
Growing sweet peas successfully involves understanding their specific needs regarding soil, light, and support. These plants thrive in cooler weather and prefer a sunny spot, though they appreciate some shade during the hottest part of the afternoon, especially in warmer climates. Preparing the soil is crucial; they prefer well-drained, fertile soil enriched with compost or well-rotted manure. Improving drainage is vital, as sweet peas dislike waterlogged roots.
Sowing Seeds and Initial Growth
Sweet peas can be sown either in autumn for earlier flowering or in spring. For autumn sowing, plant seeds in modules or pots filled with a good seed compost around late September or October. Keep them in a cool greenhouse or cold frame and plant them out in early spring. Spring sowing can occur from February to April, either indoors in pots or directly into the ground once the soil has warmed slightly. Soaking seeds overnight before sowing can improve germination rates.
When planting sweet peas, always dig a deep hole or trench and incorporate plenty of organic matter. This encourages deep root growth, which is essential for supporting the vigorous climbing habit and ensuring a prolonged flowering period, especially during dry spells.
Support Structures and Training
As soon as seedlings are established, provide them with support. This can range from simple canes and netting to more elaborate trellises, obelisks, or fences. Gently tie the young shoots to the support as they grow. Pinching out the growing tips when plants are about 15cm tall encourages bushier growth and more flowering stems. For Lathyrus odoratus, a good climbing variety, ensuring robust support is paramount to prevent breakage and maximise flower production.
Watering, Feeding, and Deadheading
Regular watering is essential, particularly during dry periods, to keep the soil consistently moist but not saturated. Apply a liquid feed high in potash every two to three weeks once the plants start to flower to encourage more blooms. Deadheading spent flowers regularly is vital; this prevents the plant from putting energy into seed production and prompts it to produce more flowers. Remove the developing seed pods promptly to ensure continuous blooming.
The key to a spectacular sweet pea display lies in consistent care, from initial sowing through to regular deadheading.
This diligent approach ensures the plants remain healthy, vigorous, and productive throughout their flowering season, providing you with a continuous supply of their exquisite blooms. Consider companion planting with plants that appreciate similar conditions, such as certain types of beans or even some hardy fuchsia plants, though avoid overcrowding.
Choosing Your Sweet Peas: Popular Varieties and Colours
The world of sweet peas offers an astonishing array of colours, forms, and fragrances, making it possible to select varieties perfectly suited to your garden's aesthetic and your personal preferences. From the classic, strongly scented heirlooms to modern, free-flowering cultivars, each type brings its own unique charm.
Classic Scents and Colours
For an intense, old-fashioned fragrance, heirloom varieties are often the best choice. 'Matucana' is a popular heirloom with small, dark crimson and violet flowers and a powerful scent. 'Henry Eckford' is renowned for its beautiful salmon-pink blooms and strong perfume, while 'Mrs. Herbert' offers lovely pale lavender flowers. These traditional types are excellent for cutting, bringing their perfume indoors.
Modern Hybrids and Unique Traits
Modern breeding has introduced sweet peas with enhanced vigour, improved disease resistance, and a wider colour palette. 'Bijou' varieties are a dwarf, non-climbing type, ideal for containers or the front of borders, offering abundant flowers without the need for tall supports. 'Spencer' types are famous for their large, frilled petals and long, strong stems, making them exceptional for floral arrangements. These include cultivars in shades of picotee (two-toned edges), stripes, and bold blocks of colour.
Colour Considerations for Garden Design
When planning your planting, consider how colours will complement each other and your overall garden scheme. Soft pastels like cream, pale pink, lavender, and sky blue create a romantic, dreamy effect, often seen in cottage garden designs. For a bolder statement, consider vibrant reds, deep purples, or bi-coloured varieties. If you're planting near other flowers, think about how their colours will interact; for instance, blue sweet peas can be stunning alongside white cosmos plants, or crimson ones next to yellow marigolds for a strong contrast.
| Variety Type | Key Characteristics | Best For |
| Heirloom (e.g., 'Matucana') | Intense fragrance, classic colours | Scent gardens, traditional displays |
| Spencer (e.g., 'Queen Alexandra') | Large, frilled petals, long stems | Cut flowers, elegant arrangements |
| Dwarf/Bush (e.g., 'Bijou') | Compact, non-climbing habit | Containers, edging, small spaces |
| Striped/Picotee | Unique bi-coloured or striped petals | Adding visual interest, unique bouquets |
Exploring seed catalogues or garden centres will reveal a vast selection, from rich blues and deep burgundies to delicate apricots and pure whites. Some varieties also offer a unique scent profile, varying from the classic sweet fragrance to more fruity or spicy notes. Understanding the mature height and growth habit is also important; for instance, while many sweet peas are climbers, bush types like 'Galaxy' offer a different approach for smaller spaces, much like compact begonia or geranium plants might.
Troubleshooting Common Sweet Pea Issues
Even with careful planning, gardeners may encounter challenges when growing sweet peas. Understanding common problems and their solutions can help ensure a successful and bountiful flowering season.
Pests and Diseases
Aphids are the most common pest affecting sweet peas, often congregating on new shoots and the undersides of leaves. They can weaken the plant and spread disease. Regular inspection and prompt action are key. A strong jet of water can dislodge small infestations, or a horticultural soap spray can be used. Ensure good air circulation around plants to minimise fungal issues like powdery mildew, which can appear as white powdery spots on leaves and stems. Avoid overhead watering late in the day.
Flowering Problems
Lack of flowers can be due to several factors. Insufficient sunlight is a primary cause; sweet peas need at least six hours of direct sun daily. Over-fertilisation with nitrogen can lead to lush foliage but few flowers. Ensure you are using a balanced fertiliser or one higher in phosphorus and potassium once flowering begins. Inconsistent watering or extreme heat can also hinder blooming. For climbers, ensure they have adequate support and are regularly deadheaded to encourage continuous flowering.
If your sweet peas are growing vigorously but not flowering, consider a light prune of the very tips of the main stems. This can sometimes shock the plant into producing flower buds, especially if it's later in the season.
Variations in Growth
Some plants may grow tall and lanky, which is often a sign of insufficient light or too much nitrogen. Conversely, stunted growth might indicate poor soil conditions, lack of water, or pest problems. Ensure you are using a good quality compost when starting seeds and enriching the planting site with organic matter. If planting directly outdoors, be patient; seedlings may appear slow to establish initially compared to nasturtiums or cosmos plants.
Addressing issues promptly, often by adjusting care routines or environmental conditions, is far more effective than waiting for problems to escalate.
By being vigilant and responsive, you can overcome most common issues, ensuring your sweet peas thrive and provide weeks of beautiful, fragrant blooms. Remember to choose varieties suited to your local climate and growing conditions for the best results.