Nasturtium

Growing Conditions

Growing Zones

Thrives in USDA Zones 3 - 11

Companion Planting

When to Plant

• Direct Sow

  After last frost; sow directly where they will grow - dislikes transplanting

• Harvest

  Harvest flowers, leaves, and green seed pods throughout season; all are edible

Organic Growing Tips

• Plant as a trap crop around brassicas - aphids and caterpillars prefer nasturtiums over cabbages.

• Check nasturtium leaves regularly and remove heavily aphid-infested stems to reduce overall pest pressure.

• Do not fertilise - rich soil produces lush leaves at the expense of flowers; lean soil maximises blooms.

• Allow spent nasturtiums to decompose in place at season's end — they return minerals to the soil, and their self-sown seedlings provide next year's trap crop without any effort, building a self-sustaining companion planting system.

Common Pests

• Black Aphids (intentional trap crop)
• Cabbage White Caterpillar (trap crop)

Taxonomy

Kingdom

Plantae

Family

Nasturtium family (Tropaeolaceae)

Genus

Tropaeolum

Species

Tropaeolum majus

Natural History

Tropaeolum majus is native to the Andes of South America, where wild forms still grow in Peru, Bolivia, and Colombia. The genus name Tropaeolum derives from the Greek tropaion - trophy pole - applied by Linnaeus because the helmet-shaped flowers and round shield-like leaves reminded him of Roman victory trophies. Spanish explorers encountered the plant in Peru in the 16th century and brought seeds to Europe, where it first appeared in botanical literature around 1576. It was initially grown in European physic gardens for its peppery leaves and soon became a popular kitchen-garden ornamental. The name nasturtium is a historical confusion: the word means "nose-twister" in Latin (nasi tortium) and was originally the name for watercress (Nasturtium officinale), borrowed and applied to Tropaeolum because of its similarly peppery flavor. Both the borrowed name and the flavor trace to the same chemistry: glucosinolates, which break down into isothiocyanates - the mustard-oil compounds that create peppery heat in watercress, horseradish, and the entire brassica family.

Traditional Use

Nasturtium reached European gardens within decades of the Spanish encounter with Peru and was almost immediately recognized as edible and ornamental - one of the earliest examples of an edible flower being deliberately cultivated in European kitchen gardens.

• Andean Origin and Spanish Introduction - Leaves and flowers

  Tropaeolum majus grows wild in the Andes and was part of the pre-Columbian Andean plant world. Related species - particularly Tropaeolum tuberosum (mashua) - were cultivated as food tubers. Spanish expeditions brought T. majus seeds to Europe in the 1550s-1560s; it appeared in European botanical literature by 1576 and was growing in the physic garden at Leiden by the late 16th century.

• European Physic and Kitchen Garden Tradition - Leaves and flowers

  John Gerard's 1597 Herball described nasturtium as "Indian cress." John Parkinson's 1629 Paradisi in Sole Paradisus Terrestris noted the peppery flavor of the leaves and the ornamental appeal of the flowers as salad material. By the 17th century it had become one of the most widely grown edible ornamentals in European kitchen gardens - valued for the flavoring its leaves and flowers added to salads and for the visual effect of its trailing stems and vivid blooms.

• Caper Substitute and Hannah Glasse's Kitchen - Green seed pods

  The green unripe seed pods were pickled in vinegar as a substitute for capers - documented in English household cookbooks from the 17th century onward. Hannah Glasse's 1747 The Art of Cookery Made Plain and Easy - one of the most influential English cookbooks of the 18th century - includes specific instructions for pickling nasturtium seeds as capers. The physical resemblance and similar piquancy made this a practical domestic substitution for an expensive imported ingredient.

• Glucosinolate Chemistry and the Watercress Name - Leaves

  The borrowed name nasturtium and the peppery flavor both trace to the same chemistry: glucosinolates, which when broken down by the enzyme myrosinase produce isothiocyanates - the compounds responsible for peppery heat in watercress, horseradish, mustard, and all brassicas. This convergent chemistry across unrelated plant families confused botanists and cooks alike and is precisely why the Tropaeolum genus ended up with a watercress name.

Nasturtium leaves, flowers, and green seed pods are all edible. The seed pods become tough and inedible when fully ripe and dry.

This information is provided for historical and educational purposes only and is not medical advice. Always consult a qualified healthcare professional before making decisions related to your health.

Morphology (Plant Structure & Identification)

• Root System

  Shallow fibrous roots from large seeds; roots resent transplant disturbance once established.

• Stem

  Soft, succulent trailing or climbing stems that sprawl over bed edges or climb with support.

• Leaves

  Round peltate leaves with the stalk attached near the center, giving an umbrella-like shape.

• Flowers

  Five-petaled flowers in yellow, orange, red, or cream, usually with a backward-pointing spur.

• Fruit

  Three-part green seed clusters that dry into large wrinkled seeds.

Known Varieties

Common cultivars worth knowing

• Alaska

  Compact plants with variegated leaves and mixed flower colors.

  Best for: containers

• Empress of India

  Dark blue-green foliage with deep red flowers.

  Best for: edible ornamental beds

• Jewel Mix

  Bushy dwarf mix with a wide range of warm flower colors.

  Best for: small gardens

• Peach Melba

  Creamy yellow flowers with peach-red centers.

  Best for: soft color schemes

• Tall Trailing Mix

  Long-vined forms that spill or climb readily.

  Best for: trellises and groundcover