How to grow Nasturtium in New Zealand
Nasturtiums are fast, cheerful annuals with round leaves and bright orange, yellow and red flowers, and every part above ground is edible, with a peppery, watercress-like bite. They are almost foolproof, flower best in poor soil and bring bees into the garden. They also self-seed and scramble freely, and Weedbusters lists garden nasturtium as an environmental weed, so keep them in the garden and out of the bush.
📖 Our full guide: How to Grow Nasturtium in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | October to February | |
| Auckland | October to February | |
| Waikato & Bay of Plenty | October to February | |
| Central North Island | November and December | |
| Wellington & Lower North Island | October to February | |
| Nelson & Marlborough | October to February | |
| Canterbury | November to January | Frost tender. Sow Nov to Jan once the frosts finish in mid October; autumn frost ends flowering. |
| Otago & Southland | November to January | Frost tender. Sow Nov to Jan after the last frost in late October; autumn frost ends flowering. |
| Central Otago | November to January | Frost tender. Sow direct Nov to Jan after the last frost in early November. Autumn frost ends it; it often reseeds. |
Where to plant
Grow nasturtiums in full sun to part shade in well-drained soil. They flower best in poorer soil: rich ground and heavy feeding give lush leaves and few flowers. Dwarf types suit pots, edges and window boxes, and trailing types will ramble over banks, climb a low fence or trellis, or spill from baskets.
Weedbusters lists garden nasturtium (Tropaeolum majus) as an environmental weed because it smothers low plants around gardens, dumps, roadsides and streams. It is not a banned plant, but pull out unwanted seedlings, never dump garden waste in reserves, and do not plant it next to bush or waterways. A different species, Chilean flame creeper (Tropaeolum speciosum), is a banned pest plant under the National Pest Plant Accord.
- Northland, Auckland, Waikato and Bay of Plenty, Wellington, and Nelson and Marlborough: sow from October to February. In frost-free gardens plants often self-seed and flower for much of the year.
- Central North Island: sow in November and December, after the frosts.
- Canterbury, Otago and Southland, and Central Otago: sow direct from November to January after the last frost. Autumn frost ends flowering, but plants often reseed.
Choosing a variety
| Type | Notes |
|---|---|
| Dwarf or bushy types (for example Jewel Mixed, Cherry Rose) | Compact, free-flowering plants for pots, edges and small beds |
| Tall trailing types | Scramble over banks or climb trellises and fences; good as a quick screen or ground cover |
| Variegated-leaf types | Decorative marbled leaves with the same edible flowers |
How to plant
- Soak the large seeds overnight to speed germination, if you like.
- Sow direct after the danger of frost has passed, about 1 to 1.5 cm deep, in clumps or rows. Seedlings can be hard to transplant, so direct sowing works best.
- Thin or space plants about 20 to 30 cm apart, more for trailing types.
- Keep the soil moist until seedlings are up.
Watering and feeding
Water in dry spells, but do not overdo it. Nasturtiums cope well with dry conditions once established.
Do not feed them, or feed only lightly in very poor soil. Rich soil and fertiliser give leaves at the expense of flowers.
Pruning and care through the year
- Remove spent flowers to keep plants flowering, and to reduce self-seeding.
- Check plants for aphids, caterpillars and whitefly; nasturtiums attract these pests first, which gives you a chance to deal with them before they move to vegetables.
- Pull out plants or seedlings that stray beyond where you want them, and put the plant material in a sealed bag or green waste bin rather than dumping it.
Harvesting
Pick flowers and young leaves as needed for salads, garnishes and pesto; they have a peppery, watercress-like flavour. Green seed pods can be pickled like capers.
Pick in the morning and use quickly, as the flowers wilt soon after picking.
Growing in pots
Dwarf nasturtiums are ideal in pots, troughs and hanging baskets in sun or part shade. Use ordinary potting mix without extra fertiliser, water when dry and deadhead often.
Companion planting
Nasturtiums are popular companion plants. Their flowers bring in bees, and they act as a decoy or trap crop, drawing aphids and caterpillars away from vegetables.
Good companions
- Cucumber Brings in bees to pollinate the flowers, and draws aphids away.
- Zucchini Brings in bees to pollinate the flowers, and draws aphids away.
- Pumpkin A trailing nasturtium can share the same sprawling space and bring in pollinators.
- Beans A trap crop that pulls aphids off nearby beans.
- Fruit trees A flowering ground cover under trees that attracts bees at blossom time.
Pests and diseases
Nasturtiums attract pests by design, so expect some aphids and caterpillars. Treat them as an early warning and a decoy rather than a problem.
Pests to watch for
- Aphids Black clusters under leaves and on stems.
- White butterfly Green caterpillars chewing the leaves; nasturtiums share the mustard-oil chemistry that draws white butterfly to brassicas.
Diseases to watch for
- Mosaic virus Mottled, yellow-streaked and distorted leaves; pull out affected plants.
Common questions
Are nasturtiums edible?
Yes. The flowers, leaves and young seed pods are all edible, with a peppery flavour. Use them in salads and pesto, or pickle the green pods like capers.
Is nasturtium a weed in New Zealand?
Weedbusters lists garden nasturtium as an environmental weed because it can smother low native plants near gardens, dumps and streams. It is not banned, but keep it in the garden, pull out strays and never dump garden waste in reserves.
Why are my nasturtiums all leaves and no flowers?
The soil is too rich or they are being fed. Nasturtiums flower best in poor soil without fertiliser.
Do nasturtiums keep pests off vegetables?
They act as a decoy: aphids, caterpillars and whitefly often go to nasturtiums first, which lets you deal with them before they reach your crops. Their flowers also bring in bees.
When should I sow nasturtiums?
After the danger of frost has passed: from October in the north and from November in the central North Island and the South Island.
Can I grow nasturtiums in a pot?
Yes. Dwarf types are ideal in pots and baskets. Do not add extra fertiliser, water when dry and deadhead often.
Sources we checked: Yates NZ: How to grow nasturtium; Kings Seeds NZ: Nasturtium Tall Trailing Mix; Weedbusters: Nasturtium; Wikipedia: National Pest Plant Accord (species list).