Nasturtium

Tropaeolum majus

Common & Folk Names

• Garden Nasturtium
• Indian Cress
• Monk’s Cress
• Capuchina
• Capucine
• Blood Flower
• Queen’s Taco
• Gallant’s Spur

Plant Family

Tropaeolaceae

Geographic Location

Native to the Andes Mountains of South America, specifically Peru, Bolivia, Colombia, and Ecuador. Now naturalised and cultivated throughout temperate regions worldwide, including parts of North America (California, New York, Pennsylvania, New Hampshire, Massachusetts, Connecticut, Virginia), Europe, Asia, Africa, and Australia. Listed as invasive in Hawaii and Lord Howe Island, Australia.

Habitat

Originally found in mountain regions of the Andes. Thrives in temperate climates and is widely cultivated in gardens, containers, and as ground cover. Adaptable to various conditions but prefers well-drained locations with good sun exposure.

Growing Conditions

Sun: Full sun to partial shade; blooms best with at least 6 hours of direct sunlight

Soil: Well-drained, moderately fertile soil; pH 6.0-7.5. Tolerates poor soil conditions (rich soil produces more foliage, less flowers). Grows well in sandy or loamy soils

Propagation: Easy from seed; direct sow after last frost or start indoors 4-6 weeks before. Seeds germinate in 7-14 days. Self-seeds readily. No scarification needed for large seeds

Care: Low-maintenance; water regularly but avoid overwatering. No fertiliser needed (excess nutrients reduce flowering). Deadhead spent flowers to encourage continuous blooming. Can be grown as trailing, climbing (with support), or bushy varieties

NZ Planting Calendar

Sowing (seeds): Spring (September–November) after frost danger passes; can also sow in summer for autumn flowers

Planting: Spring (September–November) or early summer (December)

Flowering: Approximately 6-8 weeks after sowing; December–May (summer to autumn)

Harvest (leaves/flowers): Throughout growing season; pick regularly to encourage flowering

Harvest (seeds): Autumn (March–May) when seed pods turn tan/brown and dry

Note: Not native to NZ; annual; frost-tender; self-seeds readily; can become weedy in mild climates

Harvesting Guidelines

Harvest flowers when fully open for maximum color and flavor, preferably in the morning after dew has dried. Pick leaves when young and tender, before the plant flowers, for best flavor and medicinal potency. Collect immature seed pods (green) when firm. Seeds can be harvested when mature and brown from dried seed pods. All parts are best used fresh as drying significantly reduces volatile compounds and medicinal activity. If drying is necessary, do so quickly at low temperatures (below 40°C) to minimise enzymatic degradation of glucosinolates.

Parts Used

• Flowers
• Leaves
• Seeds
• Immature seed pods
• Fresh plant juice

Constituents & their Actions

Nasturtium contains a diverse array of bioactive compounds that work synergistically to produce its therapeutic effects. The plant is particularly notable for its glucosinolate content, along with significant levels of antioxidant compounds, vitamins, and minerals that contribute to its medicinal properties.

Glucosinolates:

These sulfur-containing glycosides are the primary medicinal constituents in nasturtium and are responsible for the plant’s characteristic peppery taste and antimicrobial activity. The main glucosinolate in nasturtium is:

• Glucotropaeolin (benzyl glucosinolate) – present at approximately 1000 mg/100 g fresh matter
• Benzyl isothiocyanate (BITC) – the active metabolite formed when glucotropaeolin is hydrolyzed by the enzyme myrosinase upon tissue disruption
• Benzyl cyanide (minor component)

The main actions of these glucosinolates are:

• Antimicrobial activity: Benzyl isothiocyanate exhibits broad-spectrum antibacterial, antifungal, and antiviral properties by disrupting microbial cell membranes and interfering with metabolic processes
• Urinary antiseptic: BITC is excreted unchanged through the urinary system, where it exerts direct antimicrobial effects
• Respiratory expectorant: Volatile isothiocyanates are also excreted through the respiratory tract, providing antimicrobial activity in the lungs and airways
• Anti-inflammatory: Modulates inflammatory pathways including dual inhibition of COX and LOX enzymes
• Antiproliferative: Induces apoptosis and inhibits tumor cell growth through multiple mechanisms

Flavonoids:

These polyphenolic compounds contribute significantly to nasturtium’s antioxidant, anti-inflammatory, and vascular effects. The main flavonoids in nasturtium are:

• Quercetin and quercetin-3-O-glucoside
• Kaempferol and kaempferol glucosides
• Isoquercetin
• Myricetin

The main actions of these flavonoids are:

• Antioxidant activity: Scavenge free radicals and prevent oxidative damage to cells and tissues
• Vasodilatory effects: Promote relaxation of blood vessel walls, supporting healthy blood pressure
• Anti-inflammatory: Inhibit production of pro-inflammatory cytokines (IL-1β, TNF-α) and reduce oxidative stress
• Cardioprotective: Support healthy cholesterol metabolism and reduce oxidised LDL levels
• Metabolic support: Improve insulin sensitivity and glucose regulation

Carotenoids:

Nasturtium is exceptionally rich in carotenoids, particularly lutein, making it one of the highest plant sources of these important compounds. The main carotenoids are:

• Lutein (up to 450 μg/g in yellow flowers, 136 μg/g in leaves)
• Zeaxanthin
• β-Carotene (69 μg/g in leaves)
• Violaxanthin
• Antheraxanthin
• β-Cryptoxanthin
• Neoxanthin

The main actions of these carotenoids are:

• Eye health support: Lutein and zeaxanthin accumulate in the macula and protect against blue light damage and age-related macular degeneration
• Antioxidant protection: Neutralise singlet oxygen and lipid peroxyl radicals
• Provitamin A activity: β-Carotene converts to vitamin A in the body, supporting vision, immune function, and skin health
• Anti-inflammatory: Reduce inflammatory markers and oxidative stress

Anthocyanins:

These water-soluble pigments give nasturtium flowers their vibrant red, orange, and yellow colors and contribute significant antioxidant capacity. The main anthocyanins are:

• Pelargonidin derivatives
• Delphinidin derivatives
• Cyanidin derivatives

The main actions of these anthocyanins are:

• Powerful antioxidants: Protect cells from oxidative damage and support cellular health
• Cardiovascular support: Help maintain healthy blood vessel function and reduce inflammation
• Anti-inflammatory: Modulate inflammatory signaling pathways
• Neuroprotective: May help protect brain cells from oxidative stress

Vitamins and Minerals:

Nasturtium is particularly rich in vitamin C and various essential minerals:

• Vitamin C (approximately 130 mg/100 g in flowers)
• Potassium
• Phosphorus
• Magnesium
• Calcium
• Zinc
• Copper
• Iron
• Manganese

The main actions of these nutrients are:

• Immune support: Vitamin C enhances immune cell function and acts as a potent antioxidant
• Collagen synthesis: Vitamin C is essential for tissue repair and wound healing
• Mineral balance: Electrolytes support proper cellular function, nerve transmission, and muscle contraction

Phenolic Acids:

• Chlorogenic acid
• Hydroxycinnamic acid derivatives
• Spilantholic acid

The main actions of these phenolic acids are:

• Antioxidant activity: Protect against cellular damage and support overall health
• Antimicrobial support: Contribute to the plant’s infection-fighting properties
• Anti-inflammatory: Help modulate inflammatory responses

Actions with Mechanisms

Antimicrobial (Antibacterial, Antifungal, Antiviral):
Nasturtium’s potent antimicrobial activity is primarily mediated by benzyl isothiocyanate (BITC), which is released when plant tissues are damaged and the glucosinolate glucotropaeolin comes into contact with the enzyme myrosinase. BITC disrupts microbial cell membranes by interfering with lipid bilayer integrity, which in turn compromises the protective barrier that microorganisms rely on for survival. Additionally, BITC inhibits key metabolic enzymes within bacteria and fungi by binding to sulfhydryl groups on proteins, which in turn disrupts cellular respiration and other vital processes. This compound has demonstrated effectiveness against Staphylococcus aureus, Escherichia coli, and various fungal species. The antimicrobial compounds are also excreted through the urine and respiratory passages, providing targeted action in these systems.

Urinary Antiseptic and Diuretic:
When consumed, glucotropaeolin is hydrolysed in the gut to release benzyl isothiocyanate, which is readily absorbed in the intestines and subsequently excreted largely unchanged through the urinary system, which in turn allows it to exert direct antimicrobial effects on the urinary tract mucosa and within the urine itself. This urinary excretion creates a bacteriostatic environment that inhibits the growth and proliferation of pathogenic bacteria commonly implicated in urinary tract infections. Additionally, compounds in nasturtium promote increased urine production through both increased glomerular filtration and reduced tubular reabsorption of water, which in turn helps flush bacteria and inflammatory debris from the urinary system. Clinical studies have demonstrated effectiveness in prophylactic treatment of recurrent lower urinary tract infections.

Respiratory Expectorant and Decongestant:
Nasturtium’s volatile isothiocyanates are partially excreted through the respiratory tract, where they exert both antimicrobial and mucolytic actions. These compounds stimulate secretory cells in the bronchial mucosa to produce more fluid secretions, which in turn reduces the viscosity of thick mucus making it easier to expectorate. Additionally, the warming, stimulating properties of these volatile oils increase local blood flow to respiratory tissues, which in turn promotes clearance of congestion and supports the immune response in the airways. The essential oils and saponins also help loosen stubborn phlegm by breaking down mucopolysaccharide bonds, which in turn facilitates productive coughing and relief from chest congestion.

Anti-inflammatory:
Nasturtium demonstrates unique anti-inflammatory activity through dual inhibition of both the cyclooxygenase (COX) and lipoxygenase (LOX) pathways, the two primary enzymatic routes for producing pro-inflammatory mediators from arachidonic acid. The plant’s flavonoids and isothiocyanates suppress the production of pro-inflammatory cytokines including interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α) by interfering with NF-κB signaling, which in turn reduces the inflammatory cascade at the cellular level. This mechanism is distinct from non-steroidal anti-inflammatory drugs (NSAIDs), which primarily target only the COX pathway. Additionally, the high antioxidant content reduces oxidative stress that can trigger and perpetuate inflammation, which in turn provides comprehensive anti-inflammatory support throughout the body.

Cardiovascular Support (Hypotensive and Lipid-Lowering):
The flavonoids in nasturtium, particularly quercetin and kaempferol, promote vasodilation by stimulating endothelial nitric oxide synthase (eNOS), which in turn increases production of nitric oxide in blood vessel walls, leading to smooth muscle relaxation and reduced vascular resistance. This mechanism helps support healthy blood pressure levels. Additionally, benzyl isothiocyanate has been shown to reduce hepatic glucose production by affecting the intracellular localisation of the transcription factor FOXO1, which in turn influences insulin sensitivity and metabolic function. The plant’s glucosinolates and essential oils interfere with cholesterol absorption in the intestines and may promote bile acid excretion, which in turn helps reduce total cholesterol and LDL cholesterol levels. Clinical studies have demonstrated significant reductions in oxidised LDL, total cholesterol/HDL ratio, and atherogenic indices in prediabetic subjects.

Antioxidant:
Nasturtium’s exceptional antioxidant capacity stems from its synergistic combination of vitamin C, carotenoids, flavonoids, and anthocyanins, which work through complementary mechanisms to neutralise different types of reactive oxygen species (ROS). Vitamin C donates electrons to neutralise free radicals in aqueous environments, which in turn protects water-soluble cellular components from oxidative damage. The lipophilic carotenoids, particularly lutein and β-carotene, quench singlet oxygen and scavenge peroxyl radicals in cell membranes and lipoproteins, which in turn prevents lipid peroxidation and maintains membrane integrity. Flavonoids chelate transition metal ions that catalyse ROS formation and also directly scavenge hydroxyl radicals and superoxide anions, which in turn provides multi-level protection against oxidative stress throughout the body.

Immunomodulatory:
Nasturtium’s bioactive compounds support immune function through multiple pathways. The high vitamin C content enhances the production and function of white blood cells, particularly lymphocytes and phagocytes, which in turn strengthens the body’s ability to combat infections. Flavonoids and saponins stimulate phagocytosis–the process by which immune cells engulf and destroy pathogens, which in turn enhances innate immune defenses. Additionally, compounds in nasturtium modulate cytokine production, promoting balanced immune responses, which in turn helps prevent both insufficient immune activity (susceptibility to infection) and excessive responses (chronic inflammation). The glucosinolates may also support immune surveillance against abnormal cells.

Antiproliferative (Anticancer Potential):
Benzyl isothiocyanate from nasturtium has demonstrated multiple antiproliferative mechanisms in research studies. BITC induces apoptosis (programmed cell death) in cancer cells by activating caspase enzymes and disrupting mitochondrial membrane potential, which in turn triggers the cellular self-destruction pathway without affecting normal cells. It also interferes with DNA replication in rapidly dividing cells and inhibits the formation of new blood vessels (angiogenesis) that tumors require for growth and metastasis, which in turn may help limit tumor expansion. Additionally, BITC modulates phase II detoxification enzymes that help the body eliminate carcinogens, which in turn may reduce cancer risk. While these mechanisms have been demonstrated in vitro and in animal studies, human clinical trials are needed to establish therapeutic applications.

Main Use

Nasturtium’s primary therapeutic applications center on its antimicrobial and anti-inflammatory properties, particularly for infections and inflammation of the urinary and respiratory systems.

Internally, nasturtium is most valued as a natural urinary antiseptic for prevention and supportive treatment of recurrent urinary tract infections, bacterial cystitis, and as a kidney and bladder tonic. The herb is especially effective when used prophylactically to reduce the frequency of UTI recurrence. It is also employed for upper respiratory tract infections, bronchitis, chest colds, and as an expectorant to relieve congestion and promote productive coughing. Traditional uses include supporting immune function during cold and flu season, as a circulatory stimulant, and for metabolic support including blood sugar regulation and cholesterol management. The high vitamin C content makes it useful as a nutritive tonic, particularly during times of increased need.

Topically, nasturtium juice, infusions, or poultices are applied to minor wounds, cuts, and abrasions for their antiseptic properties. The rubefacient action (increasing local blood flow) makes nasturtium useful in topical applications for localised joint inflammation and muscular aches. Hair and scalp preparations use nasturtium infusions to stimulate hair growth, address alopecia, and relieve dandruff. Some traditional applications include treatment of skin conditions like minor eczema, acne, and fungal infections, though internal use is often combined for best results.

Preparations

Fresh Herb: Flowers, leaves, and seeds can be consumed fresh in salads, pestos, or as garnishes. Fresh juice can be extracted from leaves for topical use. Typical amount: 5-10 leaves or 3-5 flowers daily in food

Tea/Infusion: Steep 1-2 teaspoons (approximately 2-3 grams) of fresh or dried leaves and flowers in 250 mL of just-boiled water for 10-15 minutes, covered to preserve volatile oils. Strain and drink warm. For urinary or respiratory support, 2-3 cups daily between meals

Tincture (Fresh Plant): Use fresh leaves and flowers at a 1:2 ratio in 40-50% alcohol (vodka or brandy works well). Chop plant material finely, pack into jar, cover completely with alcohol, and macerate for 2-4 weeks, shaking daily. Strain and store in dark glass bottles. The tincture preserves the volatile compounds better than drying

Infused Oil: Pack fresh or wilted flowers and leaves into a clean jar, cover completely with a carrier oil (olive, sunflower, or sweet almond oil), and infuse using the traditional cold method for 4-6 weeks in a sunny location, shaking daily. Strain thoroughly and store in dark glass. Use as a base for salves, massage oils, or direct topical application

Poultice: Crush fresh leaves to a paste and apply directly to affected skin areas. Cover with clean cloth and leave for 15-30 minutes. Use for minor wounds, insect bites, or localised inflammation

Vinegar (Nasturtium “Capers”): Harvest immature green seed pods, place in clean jar, and cover with spiced vinegar (apple cider vinegar with salt, peppercorns, and herbs). Allow to mature for 2-4 weeks before using as a condiment similar to capers

Dosage

Fresh Herb (Culinary/Nutritive): 5-15 grams of fresh flowers and leaves daily, added to salads, pestos, or other foods

Dried Herb (Tea/Infusion): 2-3 grams (approximately 1-2 teaspoons) of dried herb, 2-3 times daily, steeped for 10-15 minutes

Tincture (1:2, 40-50% alcohol): 2-4 mL (approximately 40-80 drops), 3 times daily, taken in water between meals. For acute infections, may be taken 4-5 times daily for up to 2 weeks, then reduce to maintenance dose

Fresh Juice: 5-10 mL of fresh-pressed leaf juice, 2-3 times daily for internal use; apply undiluted topically to affected areas

Topical Use: Apply infused oil, fresh juice, or diluted tincture (1 part tincture to 3 parts water) to affected areas 2-4 times daily as needed. Poultices can be applied for 15-30 minutes up to 3 times daily

Note: For urinary tract support, best results are achieved with consistent use over several weeks. For prevention of recurrent UTIs, use prophylactically during susceptible periods. Always ensure adequate hydration when using nasturtium for urinary support.

Safety & Drug Interactions

Scientific Evidence

Urinary Tract Infection Prevention: A randomised, double-blind, placebo-controlled trial (Albrecht et al., 2007) demonstrated that a herbal combination containing nasturtium and horseradish significantly reduced the frequency of recurrent urinary tract infections compared to placebo. Patients receiving the herbal preparation experienced fewer infection episodes and delayed time to recurrence over the study period.

Respiratory Tract Infection Prophylaxis: A phase III randomised controlled trial (Fintelmann et al., 2012) investigated a combination product containing nasturtium for prophylactic treatment of patients with recurrent respiratory tract infections. The study found significant reduction in the number of respiratory infections and improved symptom scores in the treatment group compared to placebo, with good tolerability and safety profile.

Anti-inflammatory Activity: Laboratory research (Tran et al., 2016) using human peripheral blood mononuclear cells demonstrated that nasturtium extract dually blocks both COX and LOX inflammatory pathways in a concentration-dependent manner. This unique mechanism of action differs from conventional NSAIDs and suggests potential therapeutic applications for inflammatory conditions, though clinical trials in humans are needed.

Cardiovascular and Metabolic Effects: A pilot crossover study (Barrantes-Martínez et al., 2022) in prediabetic subjects found that consumption of freeze-dried nasturtium containing benzyl glucosinolate for 4 weeks resulted in significant reductions in LDL cholesterol, oxidised LDL, and multiple cardiovascular risk indices including Castelli’s risk index and atherogenic coefficient. These findings suggest potential benefits for cardiovascular disease prevention, particularly in metabolic syndrome.

Antimicrobial Activity: Multiple in vitro studies have confirmed broad-spectrum antimicrobial properties of nasturtium extracts and benzyl isothiocyanate against various bacterial and fungal pathogens. Research has demonstrated effectiveness against Staphylococcus aureus, Escherichia coli, and other common pathogens. Additionally, studies on benzyl isothiocyanate bioavailability (Platz et al., 2016) confirmed that the compound is absorbed and excreted through urine, supporting traditional use for urinary infections.

Antiproliferative Research: In vitro and in vivo studies (Pintao et al., 1995) have demonstrated that benzyl isothiocyanate from nasturtium exhibits antitumor activity against various cancer cell lines. The compound induces apoptosis and inhibits cell proliferation through multiple mechanisms. While these results are promising, human clinical trials are necessary to establish any therapeutic role in cancer treatment.

Western Energetics

Temperature: Warming and Stimulating. Nasturtium has a distinctly warming quality that increases circulation, promotes perspiration, and stimulates metabolic activity. The pungent, spicy taste from volatile mustard oils creates a heating sensation that warms cold, stagnant conditions. This warming energy makes nasturtium particularly useful for cold, damp respiratory conditions with copious clear or white phlegm, and for individuals who tend toward coldness with poor circulation.

Moisture: Drying with Stimulating Fluid Movement. The herb has a drying action on excessive secretions and boggy, waterlogged tissues, making it valuable for conditions characterised by dampness such as chronic catarrh, lymphatic congestion, and edema. However, it simultaneously stimulates fluid secretions in specific ways–promoting productive expectoration in the lungs and increasing urine flow in the kidneys. This apparent paradox reflects its ability to mobilise and move stagnant fluids rather than simply drying tissues.

Tissue State: Best suited for atonic (weak, deficient, underactive) and congestive (stagnant, boggy, accumulated) tissue states. Nasturtium excels at stimulating sluggish, weakened systems back into action–strengthening digestive fire, activating slow circulation, and energising underperforming immune responses. It also addresses congested conditions by moving stagnant fluids, clearing accumulated mucus, and promoting elimination through multiple channels (urinary, respiratory, lymphatic). The warming, stimulating nature makes it less suitable for hot, inflamed, or tense tissue states where cooling, soothing herbs would be more appropriate.

Taste

Pungent: The dominant pungent, peppery taste comes from the mustard oil glycosides (glucosinolates) that break down into volatile isothiocyanates when plant tissues are damaged. This sharp, spicy quality stimulates digestive secretions, increases circulation, moves stagnation, and has a warming, dispersing action on the body. The pungent taste correlates with nasturtium’s antimicrobial properties, ability to clear congestion, and stimulating effects on sluggish systems. This taste quality also indicates the herb’s affinity for the respiratory and urinary systems where pungent herbs have traditional application.

Bitter: A subtle bitter undertone from the flavonoids and phenolic compounds supports nasturtium’s cooling actions on inflammation and its liver-supporting properties. The bitter taste stimulates digestive secretions and supports detoxification processes, complementing the warming pungency to create balanced action. This quality contributes to the plant’s ability to support metabolic function and reduce excess heat associated with inflammation.

Sweet: A mild sweet quality, particularly noticeable in fresh flowers, comes from the plant’s nutritive components including vitamin C, minerals, and carotenoids. This sweet aspect provides nourishment, supports tissue building, and balances the more dispersing pungent properties. The sweet taste relates to nasturtium’s tonic and nutritive applications, making it suitable for gentle, sustained use rather than only acute intervention.

Plant Lore

The genus name Tropaeolum comes from the Latin tropaeum, meaning “trophy,” bestowed by the Swedish botanist Carl Linnaeus who observed that the round, shield-shaped leaves resembled the shields of Roman warriors, while the bright orange and red flowers reminded him of blood-stained helmets displayed on trophy poles after battle victories. This martial imagery captured the plant’s bold, conquering nature as it rapidly spreads across garden spaces.

Native to the Andes mountains of Peru, Bolivia, and Colombia, nasturtium was brought to Europe by Spanish conquistadors in the 16th century, around 1686. Initially grown as an ornamental curiosity for its spectacular flowers, European herbalists soon recognised its medicinal properties and peppery, cress-like taste. The common name “Indian cress” reflects this flavor similarity to watercress, as well as the plant’s New World origins.

In traditional Andean medicine, indigenous peoples used nasturtium as a disinfectant, wound-healing herb, and for respiratory complaints long before European contact. They recognised the plant’s antibiotic properties, applying fresh leaves and flowers to injuries to prevent infection and consuming it to support recovery from illness.

During the Victorian era, nasturtiums became hugely popular in cottage gardens throughout Europe, valued both for their cheerful, abundant blooms and as a practical culinary herb. The flowers adorned plates and salads at garden parties, while the piquant leaves added flavor to sandwiches and garnishes. The immature seed pods, pickled in vinegar and spices, served as a substitute for expensive imported capers, bringing a similar tangy, briny taste to dishes at a fraction of the cost.

In the language of flowers, nasturtiums symbolised conquest and victory in battle, again referencing their martial connection, but also represented patriotism and loyalty. Given as gifts, they could convey the message “I will overcome all obstacles” or express admiration for someone’s fighting spirit and resilience.

Gardeners have long valued nasturtiums as companion plants, believing they attract aphids and other pests away from precious vegetables while repelling whiteflies and squash bugs. Modern research has confirmed that nasturtiums do indeed serve as “trap crops,” drawing pests to themselves and protecting neighboring plants.

In 2013, nasturtium was named Medicinal Plant of the Year in recognition of its antimicrobial properties and traditional use in treating infections, bringing renewed attention to this cheerful, therapeutic herb that has supported human health for centuries.

Additional Information

Edible Uses: All above-ground parts of nasturtium are edible with a pleasant peppery flavor. Flowers make colorful, nutritious additions to salads and garnishes. Young leaves work well in sandwiches, pestos, and as cooked greens. The immature green seed pods can be pickled like capers. Seeds should only be consumed when very young and tender, as mature seeds can be excessively pungent and potentially irritating.

Nutritional Value: Nasturtium ranks among the most nutrient-dense edible flowers, containing approximately 130 mg of vitamin C per 100 g (similar to parsley), making it an excellent immune-supporting food. The flowers contain up to 45 mg of lutein per 100 g–the highest amount found in any edible plant–making nasturtium exceptional for eye health. The plant is also a good source of minerals including potassium, phosphorus, magnesium, calcium, iron, zinc, and copper.

Cultivation Tips: Nasturtiums are vigorous, fast-growing plants that thrive on neglect. Rich, fertile soil produces lush foliage but fewer flowers; poor to average soil encourages better flowering. They self-seed readily and can become invasive in favorable conditions. Different varieties include bushy types (30-45 cm tall), trailing types (up to 1.8 m), and climbing varieties that require support. Colors range from cream and yellow to orange, red, and deep mahogany.

Companion Planting: Nasturtiums are excellent companion plants in vegetable gardens. They attract beneficial insects including bees and pollinators, while also serving as a trap crop for aphids, whiteflies, and cabbage moths. Plant near brassicas (cabbage, broccoli, kale), tomatoes, cucurbits (squash, pumpkins, cucumbers), and fruit trees. Some gardeners report that nasturtiums repel certain pests through allelopathic compounds in their roots.

Preserving Volatile Compounds: The medicinal potency of nasturtium relies heavily on volatile compounds (benzyl isothiocyanate) that are easily lost through improper handling. When drying is necessary, process quickly at temperatures below 40°C and in the dark to minimise enzymatic degradation. Fresh preparations (tinctures, infused oils) better preserve active constituents than dried herb. Fresh-frozen flowers and leaves maintain potency better than air-dried material.

Aotearoa New Zealand Context: Nasturtiums grow readily throughout New Zealand and are popular in cottage gardens. They thrive in the temperate climate and can become weedy if not managed. Seeds and plants are widely available from garden centers and seed companies including Kings Seeds, Egmont Seeds, and local nurseries. Fresh nasturtium flowers and leaves can sometimes be found at farmers’ markets. The plant self-seeds enthusiastically in New Zealand conditions, providing continuous harvests with minimal care.

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