How to Grow Nasturtium
Tropaeolum majus
In mild or frost-free gardens, nasturtiums persist as evergreen or semi-evergreen perennials, trailing over walls, banks, and fences year after year. They need no feeding — poor soil gives the best flowers. Cut back hard in late winter if growth becomes leggy, and new shoots appear quickly. Edible leaves, flowers, and green seedpods provide a peppery harvest almost year-round. Still attracts blackfly, making it a valuable companion plant near vegetables.
Yearly Lifecycle
Care Essentials
Don't feed — poor soil produces more flowers. Rich soil produces all leaves.
Watch For
- Blackfly (use as a trap crop)
- Cabbage white caterpillars
- Powdery mildew in late summer
Companions
Beans, Fruit trees, Tomatoes, Roses
Pet Safety
Care Requirements
Light
Full sun to light shade
Flowers best in full sun but tolerates light shade. More shade means more foliage, fewer flowers.
Watering
Light watering — drought tolerant
Water lightly and infrequently once established. Drought-tolerant. Overwatering promotes foliage over flowers.
Fertilizing
No feeding — poor soil preferred
Do not feed. Nasturtiums flower best in poor, lean soil. Any fertiliser shifts energy to leaf production.
Pruning
Hard prune February, deadhead through summer
Cut back hard to 10-15cm in late winter. Remove leggy or frost-damaged stems any time. Deadhead to prolong flowering.
Growing Tips
Starve for flowers
Never feed perennial nasturtiums. Poor, free-draining soil produces masses of flowers; rich soil gives only leaves.
Hard prune in late winter
Cut back all growth to 10-15cm in February. Fresh shoots appear within weeks and the plant stays compact.
Use as a living mulch
Let trailing stems cover bare ground beneath fruit trees or along fence lines — they suppress weeds and attract aphids away from crops.
Pests & Diseases
Pest Black Bean Aphid (Blackfly)
Identification: Dense colonies of black aphids on stems, leaves, and flower buds, sticky honeydew, sooty mould
- Squash colonies by hand or blast off with water
- Encourage ladybirds, lacewings, and hoverflies
- Remove heavily infested shoots and dispose of them
- Pyrethrum-based contact spray (rarely needed on a trap crop)
Pest Cabbage White Caterpillars
Identification: Large ragged holes in leaves, green-yellow caterpillars with black markings
- Hand-pick caterpillars and eggs
- Accept some damage — perennial nasturtiums recover quickly
- Rarely warranted on ornamental plants
Disease Powdery Mildew Erysiphe cruciferarum
Symptoms: White powdery coating on leaves, especially in late summer. Leaves yellow and become distorted.
Treatment: Remove badly affected leaves. Improve air circulation. Cut back congested growth.
Prevention: Space plants well. Avoid drought stress. Grow in full sun with good airflow.
Spacing & Planting
| Plant spacing | 45 cm |
| Row spacing | 60 cm |
| Mature height | 60 cm |
| Mature spread | 200 cm |
Perennial nasturtiums spread vigorously via trailing stems. Allow generous space or grow against a wall, fence, or bank where they can cascade freely.
