What Are Nasturtiums?
Nasturtiums are renowned for their striking trumpet-shaped flowers and broad, lily-pad-like leaves, offering a splash of colour in shades of orange, yellow, red, and pink. Native to South America, these cheerful annuals are exceptionally rewarding for gardeners of all skill levels. Beyond their visual appeal, nasturtiums possess a unique peppery flavour, making both their flowers and leaves a culinary delight, often used in salads and garnishes. Their vigorous growth habit and adaptability also make them a valuable addition for companion planting, deterring certain pests while attracting beneficial insects. Understanding the basics of nasturtiums growing ensures a season of abundant blooms and delightful flavours.
The appeal of nasturtiums lies in their dual utility: they are ornamental plants that also provide edible components. This makes them a favourite for kitchen gardens as much as for flower borders. Their growth is relatively unhindered by specific soil types, thriving even in poorer conditions, which often leads to more flowers and less foliage. This resilience is a key factor in their popularity for those new to gardening or seeking low-maintenance additions.
Why Choose Nasturtiums for Your Garden?
Nasturtiums bring a multitude of benefits to any garden space. Primarily, they provide continuous, vibrant blooms from early summer until the first frosts, offering sustained visual interest. Their low maintenance requirements mean they are forgiving for novice gardeners; they tolerate a range of soil conditions and require minimal feeding, particularly if the soil is rich, as this can encourage leaf growth over flowers. They are also remarkably drought-tolerant once established, needing only moderate watering.
Beyond aesthetics, nasturtiums serve a practical role in garden ecosystems. Their strong scent can deter common garden pests like aphids, whiteflies, and squash bugs, acting as a natural repellent. Simultaneously, their bright flowers can attract pollinators such as bees. For those interested in a productive garden, the edible nature of nasturtiums adds another layer of appeal. The flowers and young leaves offer a peppery, slightly spicy taste that can elevate salads, stir-fries, and other dishes, providing a unique ingredient straight from your own plot.
Plant nasturtiums in a location that receives at least six hours of sunlight daily for the most prolific flowering.
Consider their growth habits when deciding where to place them. Trailing varieties can cascade beautifully over walls or spill from hanging baskets, while bush varieties remain more compact, fitting well into mixed borders or containers. Their versatility means they can be integrated into various garden designs, providing colour and utility where needed.
Understanding Nasturtium Varieties
Nasturtiums are broadly categorised into two main types: bush and climbing (or trailing). Bush varieties, such as 'Alaska' or 'Tom Thumb', grow to a more compact height, typically 25-35 cm, making them suitable for containers, edging, or filling gaps in beds. They produce abundant flowers over a denser plant structure.
Climbing nasturtiums, like 'Moonlight' or 'Glorious Gleam', can scramble and trail up to 2-3 metres, making them ideal for covering trellises, walls, or fences, or for trailing over the edges of raised beds and containers. They offer a more dramatic visual impact and can be trained to grow in specific directions, adding vertical interest to the garden.
Within these types, flower colours range from pale lemon and apricot to deep crimson and fiery scarlet, often with unique markings. Leaf shapes also vary, with some varieties featuring variegated foliage, adding an ornamental touch even before the flowers appear. Choosing the right variety depends on the intended use and available space, whether for a riot of colour in a sunny border or a fragrant cascade in a hanging basket.
Getting Started with Nasturtiums Growing
Initiating nasturtiums growing is straightforward, thanks to their large seeds that are simple to handle and sow. They prefer a sunny spot and well-draining soil, though they are not overly fussy. In fact, planting them in soil that is too rich can result in lush foliage at the expense of flowers, and they often perform better with slightly leaner soil.
Sowing Nasturtium Seeds
Nasturtiums can be sown directly into the ground after the last frost has passed, or started indoors a few weeks earlier for a head start. For direct sowing, create shallow holes about 2-3 cm deep and space seeds roughly 20-30 cm apart, depending on the variety's mature size. If planting in succession, sow new seeds every few weeks to ensure a continuous display of flowers throughout the season.
When starting seeds indoors, use small pots or seed trays filled with a good quality seed compost. Plant one or two seeds per pot at a depth of about 2 cm. Keep them in a warm location with good light. Once seedlings have developed a few true leaves and the risk of frost has passed, they can be carefully transplanted into their final positions. It's important to handle their roots gently, as nasturtiums dislike root disturbance, which can slow their growth.
A common mistake is over-watering young seedlings; allow the soil to dry slightly between waterings.
Consider the mature size of the plant when spacing them out. Bush types require less room than their climbing counterparts. Proper spacing ensures good air circulation, which helps prevent fungal diseases, and allows each plant to develop to its full potential without overcrowding.
Ideal Growing Conditions and Soil Preparation
Nasturtiums thrive in full sun, needing at least six hours of direct sunlight per day to produce abundant flowers. While they can tolerate partial shade, flowering may be reduced. They are adaptable to various soil types but perform best in well-drained soil. Heavy clay or waterlogged conditions should be avoided, as this can lead to root rot. If your soil is heavy, incorporating grit or compost can improve drainage.
As mentioned, avoid overly fertile soil. If you have rich garden soil, it might be beneficial to mix in some coarse sand or gravel to reduce the nutrient content. For container growing, use a good quality, peat-free potting mix, and again, avoid formulations that are too heavily fertilised. A standard potting mix with added perlite for drainage is usually sufficient. For nasturtiums, less is often more when it comes to soil fertility, encouraging a healthier, more floriferous plant.
Ensure adequate drainage for containers by using pots with drainage holes and a suitable potting medium.
Watering needs are moderate. Once established, nasturtiums are relatively drought-tolerant. Water deeply but infrequently, allowing the soil to dry out slightly between waterings. Overwatering, especially in cooler weather, can promote disease and reduce flowering. Young plants and those in containers will require more frequent watering than established plants in the ground.
Caring for Your Nasturtiums
Once established, nasturtiums are remarkably low-maintenance plants, making them a rewarding choice for gardeners. Their primary needs revolve around adequate sunlight, appropriate watering, and occasional attention to deadheading or pest control. By providing these basic elements, you can ensure a continuous display of their vibrant blooms and peppery leaves throughout the growing season.
Watering and Feeding
Nasturtiums prefer their soil to dry out slightly between waterings. Water thoroughly when the top centimetre or two of soil feels dry to the touch. This approach encourages stronger root development. Established plants in the ground can often manage with natural rainfall, but during prolonged dry spells, supplemental watering is advisable. Plants grown in containers will dry out more quickly and will need more frequent attention, especially during hot weather.
In terms of feeding, nasturtiums generally do not require much fertiliser, especially if planted in moderately fertile soil. In fact, over-fertilising can lead to excessive leaf growth and fewer flowers. If you are growing them in very poor soil, a light application of a balanced, diluted liquid fertiliser once or twice during the growing season can be beneficial, but avoid high-nitrogen formulations. The focus should be on encouraging bloom rather than vegetative growth.
For bush varieties, pinch back young plants to encourage a bushier habit and more flowers.
Regularly check the moisture level of the soil, particularly in warmer months and for plants in containers. The colour of the leaves can be an indicator; wilting or pale leaves might suggest a need for water, though overwatering can also cause wilting. It is always better to err on the side of slightly too dry than too wet for nasturtiums.
Pest and Disease Management
Nasturtiums are generally robust and resistant to many common garden pests and diseases. However, they can occasionally be affected by aphids, particularly on new growth, and slugs and snails may nibble on young plants or leaves. Cabbage white butterflies might lay eggs on the leaves, leading to caterpillars that can devour them.
To manage aphids, a strong jet of water can often dislodge them. Alternatively, a dilute solution of insecticidal soap can be used. For slugs and snails, physical barriers like copper tape around pots, diatomaceous earth, or regular manual removal can be effective. If caterpillars are a problem, they can be picked off by hand. Due to their strong scent, nasturtiums often act as a deterrent to other pests in the garden, making them good neighbours for more susceptible plants.
The best defence against most nasturtium problems is a healthy plant in the right conditions.
While not common, fungal diseases like powdery mildew can appear, especially in humid conditions or with poor air circulation. Ensuring good spacing between plants and avoiding overhead watering, particularly in the evening, can help prevent this. Affected leaves can be removed to prevent spread.
Deadheading and Harvesting
While nasturtiums don't strictly require deadheading in the same way some other flowering plants do, removing spent flowers can encourage the plant to produce more blooms rather than focus on seed production. Snip off the faded flowers at the stem just above a leaf node. This process keeps the plant looking tidy and promotes continuous flowering.
The peppery leaves and flowers can be harvested throughout the growing season. For the best flavour and tenderness, harvest young leaves and buds. The flowers are best picked in the morning after the dew has dried. Use them fresh in salads, as a garnish for savoury dishes, or even crystallised for decorative edible treats. The seeds, when mature, can also be harvested and pickled to create a caper substitute.
Creative Uses and Companion Planting
Beyond their straightforward cultivation, nasturtiums offer a wealth of creative applications in the garden and kitchen. Their vibrant colours and peppery taste make them a versatile plant for both ornamental and practical purposes. Understanding their role in companion planting can also enhance the health and productivity of your vegetable patch and flower beds, offering synergistic benefits to neighbouring plants.
Nasturtiums in the Kitchen
The entire nasturtium plant is edible, offering a delightful peppery flavour that ranges from mild to quite pungent, depending on the variety and growing conditions. The flowers are perhaps the most popular part, adding a beautiful splash of colour and a spicy kick to salads, pasta dishes, and canapés. They can also be stuffed with soft cheese or used to garnish desserts for an unexpected twist.
Young leaves, often referred to as 'poor man's pepper', can be used in sandwiches, blended into pesto, or added to stir-fries for a zesty flavour. The seed pods, known as 'nasturtium capers', can be pickled in brine or vinegar and used as a condiment, mimicking the flavour of true capers. For culinary use, it is advisable to grow nasturtiums specifically for harvesting, ensuring they are not treated with any pesticides or chemicals. Varieties like 'Alaska' with variegated leaves or the rich reds of 'Mahogany' offer visual appeal on the plate.
Harvest nasturtium flowers and leaves in the morning after the dew has evaporated for the best flavour and appearance.
When experimenting with nasturtium recipes, remember that their peppery intensity can vary. Start with smaller quantities and adjust to your preference. They pair well with mild cheeses, fresh greens, and seafood, offering a flavour profile that can cut through richness and add brightness.
Companion Planting Benefits
Nasturtiums are renowned as excellent companion plants, particularly in vegetable gardens. Their strong, distinctive scent is believed to confuse or deter common pests such as aphids, whiteflies, squash bugs, and cucumber beetles. Planting them near brassicas (like broccoli, cabbage, and kale), cucumbers, tomatoes, and fruit trees can help protect these more vulnerable crops.
They can also act as a 'trap crop' for aphids, attracting them away from more valuable plants. If aphids become a problem on the nasturtiums themselves, they can then be more easily managed or the affected plants removed. For gardeners looking to deter specific pests, strategically placed nasturtiums can offer a natural, chemical-free solution. Consider planting them around the perimeter of your vegetable patch or interspersed among rows of susceptible crops.
Pairing nasturtiums with crops like beans, peas, and corn can offer mutual protection against pests.
In addition to pest deterrence, nasturtiums can also attract beneficial insects like hoverflies, which prey on aphids. Their sprawling habit can also help suppress weeds and retain soil moisture, benefiting surrounding plants. Their vibrant colours can also attract pollinators, contributing to the overall biodiversity of your garden, much like flowers such as marigolds or sweet peas do.
Alternatives and Complementary Plants
While nasturtiums are unique, other plants offer similar benefits or aesthetic qualities. For vibrant, edible flowers and a peppery note, borage is an excellent choice, with its star-shaped blue flowers and cucumber-like flavour. Calendula, with its sunny orange and yellow petals, is also edible and adds cheerful colour. For a strong pest-deterring effect, marigolds (Tagetes species) are well-known for repelling nematodes in the soil and deterring other pests.
If you are seeking plants with a similar vigorous, trailing habit for hanging baskets or ground cover, consider lobelia or petunias for pure visual impact, or fuchsia for its delicate, hanging blooms. For edible leaves with a different flavour profile, consider opting for herbs like basil, parsley, or chives, which also thrive in similar conditions. If the goal is simply adding colour and attracting pollinators, plants like sunflowers, zinnias, or cosmos offer abundant blooms. Each offers a different aspect of what makes nasturtiums so popular – be it edibility, pest deterrence, or sheer visual appeal.