Nasturtiums are among the easiest, most generous flowers a South African gardener can grow. They germinate quickly, cope with relatively poor soil, tolerate short dry spells once established, attract pollinators, and produce edible flowers and leaves with a fresh, peppery flavour. Their jewel-coloured blooms spill beautifully from pots, scramble over borders, and soften walls or fences when given support.
This guide explains how to grow nasturtiums from seed in South Africa, including the best sowing time for different climates, soil preparation, watering, container care, harvesting, common problems, and practical ways to use the flowers in the kitchen. If you’re ready to plant, start with our Nasturtium Flower Seeds – Edible, Non-GMO.
Why Nasturtiums Are Ideal for South African Gardens
Nasturtiums, botanically known as Tropaeolum majus, originated in South America but adapt well to many South African conditions. They appreciate sunshine, moderate water, and free-draining soil. Unlike flowers that demand rich beds and constant feeding, nasturtiums often bloom best where the soil is only moderately fertile.
They are especially useful in smaller gardens because one plant can do several jobs. Nasturtiums provide bright ornamental colour, feed bees and other pollinators, cover bare soil, trail from containers, and supply edible leaves and flowers. Their quick growth also makes them rewarding for beginners and children.
For more ideas on combining beauty and food in one planting, read The Edible Garden: Flowers You Can Actually Eat.
When to Plant Nasturtium Seeds in South Africa
The best planting time depends on local heat and frost. Nasturtiums prefer mild to warm conditions, but extreme midsummer heat can shorten flowering. Frost damages the soft growth.
Highveld and frost-prone inland regions
Sow from late August or September after the most severe frost has passed. A second sowing in early autumn can work in protected positions, although plants may need protection from winter frost.
Western Cape winter-rainfall regions
Sow in autumn for winter and spring colour, or sow again in late winter to early spring. Avoid placing young plants in waterlogged winter soil. Good drainage is essential.
KwaZulu-Natal and humid subtropical areas
Sow during the milder parts of spring and autumn. Provide airflow and avoid keeping foliage constantly wet, because humid conditions can encourage fungal problems.
Karoo, Northern Cape, and hot dry regions
Plant in early spring or autumn so plants establish before extreme heat. Afternoon shade can help in very hot gardens, and mulch reduces moisture loss.
Our complete South African spring planting calendar provides broader seasonal guidance for flowers, herbs, and edible crops.
Choosing the Best Position
Nasturtiums flower most freely in full sun, ideally receiving at least six hours of direct light. In regions with intense summer heat, light afternoon shade can prevent stress and scorched leaves. Too much shade produces long, soft stems and fewer flowers.
Allow room for the plant’s natural habit. Trailing nasturtiums can spread across the ground, tumble over a raised bed, or cascade from a hanging basket. If you want vertical growth, guide young stems onto a low trellis, wire frame, or fence. They do not cling as aggressively as true climbing vines, so occasional tying may be necessary.
Preparing the Soil
Nasturtiums prefer loose, free-draining soil. They do not need heavily enriched beds. In fact, too much nitrogen creates impressive leaves but disappointing flowers. If your soil is reasonably workable, simply loosen it and remove weeds before sowing.
Heavy clay should be improved with compost and drainage material, while extremely sandy soil benefits from a modest amount of compost to retain moisture. Avoid adding large quantities of manure or high-nitrogen fertiliser.
For containers, use a quality potting mix with drainage holes at the base. A pot at least 25–30 cm wide gives roots enough space and dries out less quickly than a tiny container.
How to Sow Nasturtium Seeds
- Water the soil first. Begin with evenly moist soil rather than flooding the bed after planting.
- Sow 2–3 cm deep. Nasturtium seeds are large enough to handle individually.
- Space seeds 20–30 cm apart. Closer spacing creates faster coverage, while wider spacing improves airflow.
- Cover and firm gently. Good contact between seed and soil supports reliable germination.
- Keep evenly moist. Do not leave the seedbed waterlogged.
Under suitable conditions, seedlings often appear within 7–14 days. Cooler soil can delay germination. If you are new to sowing, our spring seed-starting guide covers watering, soil preparation, and early seedling care.
Direct Sowing or Seed Trays?
Direct sowing is usually best because nasturtiums grow quickly and do not enjoy unnecessary root disturbance. Place each seed where you want the plant to mature. This saves time and allows roots to establish naturally.
Seed trays can still be useful in cold regions where gardeners want an early start. Use individual cells or small biodegradable pots, and transplant while seedlings are young. Handle the root ball carefully and harden plants off gradually before moving them outdoors permanently.
Watering Nasturtiums Correctly
Keep the soil consistently moist during germination and early establishment. Once plants are growing strongly, allow the upper layer of soil to dry slightly between waterings. Deep, less frequent watering encourages better roots than a light daily sprinkle.
Container-grown nasturtiums dry faster and may need more regular watering, particularly during hot or windy weather. Check the soil with a finger rather than following a rigid timetable. Yellowing leaves and constantly wet soil can indicate overwatering, while limp foliage and dry soil indicate thirst.
Do Nasturtiums Need Fertiliser?
Usually, very little. If plants produce masses of leaves with almost no flowers, stop feeding and check whether the soil is overly rich. A balanced, diluted feed can help container plants after extended growth, but high-nitrogen products should be avoided.
The best strategy is to begin with modestly fertile soil, provide enough sun, and resist the temptation to overfeed.
Growing Nasturtiums in Pots and Hanging Baskets
Nasturtiums are excellent container plants. Their trailing habit creates a generous display without complicated pruning. Use a container with drainage holes and place it where the plant receives morning sun or several hours of direct light.
For a full basket, sow several seeds evenly around the container rather than crowding them in the centre. Water thoroughly whenever the upper soil begins to dry. Remove faded flowers to keep the display tidy and encourage further blooming.
On a balcony, protect containers from severe wind. A heavy pot or secure railing planter is safer than a lightweight container. Nasturtiums can also share a large container with compact herbs, provided every plant has enough root space.
Using Nasturtiums as Companion Plants
Nasturtiums are often planted near vegetables because they attract pollinators and can draw aphids away from more valuable crops. They are commonly grown near brassicas, tomatoes, beans, cucumbers, and fruit trees. Companion planting is not magic, but diverse planting can create a more balanced garden and make pest populations easier to notice.
Inspect leaves regularly. If nasturtiums attract a heavy aphid infestation, remove badly affected shoots, wash smaller colonies away with water, or encourage beneficial insects. Avoid broad-spectrum pesticides, especially when you intend to eat the flowers.
How Long Until Nasturtiums Flower?
In warm conditions, nasturtiums can begin flowering approximately six to eight weeks after sowing. Temperature, sunlight, soil fertility, and variety influence the timing. Plants grown in shade or rich soil may take longer and produce more foliage than flowers.
Regular picking and deadheading help keep plants productive. Allow a few flowers to form seed if you want to save seed for a future season.
Common Nasturtium Problems
Lots of leaves but no flowers
The most common causes are excessive nitrogen and insufficient sunlight. Stop fertilising, move containers into stronger light, and allow the plant time to adjust.
Yellow leaves
A few old yellow leaves are normal. Widespread yellowing can result from overwatering, poor drainage, severe dryness, or exhausted container soil. Check moisture and drainage before adding fertiliser.
Aphids
Aphids often gather on tender stems and beneath leaves. Remove affected tips, rinse colonies off, and support ladybirds and other beneficial insects. A wildlife-friendly garden naturally provides more pest control; see our guide to creating a wildlife-friendly garden corner.
Chewed leaves
Snails, slugs, and caterpillars may feed on young growth. Inspect plants in the evening, remove pests by hand, and keep hiding places such as boards and dense debris away from seedlings.
Powdery or marked foliage
Improve airflow, water at soil level, and avoid wetting leaves late in the day. Remove badly affected material and dispose of it away from the compost heap if disease is severe.
Are Nasturtiums Edible?
Yes. The flowers and leaves are widely used as edible garnishes and ingredients. They have a peppery flavour similar to watercress. Use only correctly identified nasturtiums grown without chemicals unsuitable for food crops. Never eat flowers sourced from a florist or ornamental display unless their growing history is known.
Introduce any unfamiliar edible flower in a small quantity. Wash gently just before use and inspect for insects. For broader safety and harvesting advice, read Edible Flowers 101.
Ways to Use Nasturtiums in the Kitchen
- Scatter petals and small flowers over green salads.
- Add chopped leaves to herb butter or soft cheese.
- Use whole flowers as a garnish for soups, savoury tarts, and platters.
- Blend leaves with herbs, nuts, oil, and cheese for a peppery pesto.
- Infuse clean petals into vinegar for colour and flavour.
- Use flowers to decorate canapés immediately before serving.
Harvest in the cool morning after dew has dried. Choose fresh, undamaged blooms and use them promptly. Store briefly in a covered container in the refrigerator if necessary.
Harvesting and Saving Nasturtium Seeds
After flowering, nasturtiums form rounded green seeds that enlarge and eventually dry. For seed saving, allow mature seeds to fall naturally or collect them when they loosen easily. Dry them in a single layer in a shaded, airy place until fully hard.
Store dry seed in a labelled paper envelope inside a cool, dark, dry container. Include the variety and collection date. Moist seed can develop mould, so patience during drying is important.
Design Ideas for Nasturtiums
Use trailing nasturtiums to soften the edge of a raised vegetable bed, spill over terracotta pots, or cover bare ground beneath taller edible plants. Orange, red, and yellow blooms combine beautifully with blue borage, purple violas, white alyssum, and airy cosmos.
For an edible display, combine nasturtiums with herbs close to the kitchen. In a wildlife garden, pair them with Cosmos Seeds and Sunflower Seeds to provide varied flower shapes and feeding opportunities for pollinators.
Frequently Asked Questions
What month should I plant nasturtium seeds in South Africa?
In most frost-prone regions, sow from late August or September after severe frost has passed. In mild winter-rainfall climates, autumn and late winter sowings can also perform well. Choose a period without extreme heat or frost.
Should I soak nasturtium seeds before planting?
Soaking is not essential. The seeds generally germinate reliably when planted in moist soil. Some gardeners soak them for a few hours, but good soil moisture and warmth matter more.
Can nasturtiums grow in shade?
They tolerate partial shade but flower best with at least six hours of direct sun. Too much shade causes long stems and fewer blooms.
Why are my nasturtiums not flowering?
Excess fertiliser, rich soil, insufficient sunlight, or extreme heat can reduce flowering. Stop high-nitrogen feeding, increase light where possible, and keep watering consistent.
Can I grow nasturtiums in pots?
Yes. Use a well-drained container at least 25–30 cm wide, provide strong light, and water whenever the upper soil begins to dry.
Are nasturtium leaves edible as well as the flowers?
Yes. Both are edible and have a peppery flavour. Use only plants grown without unsuitable chemical treatments and introduce new foods gradually.
Do nasturtiums come back every year?
They are commonly grown as annuals, but they self-seed readily in favourable climates. New seedlings may appear the following season if mature seed is allowed to fall.
How far apart should nasturtiums be planted?
Space plants about 20–30 cm apart. Give vigorous trailing plants more room where airflow is limited.
Do nasturtiums attract bees?
Yes. Their bright flowers attract bees and other pollinators, making them useful in edible and wildlife-friendly gardens.
Where can I buy nasturtium seeds in South Africa?
Shop Diamond Field Blooms Nasturtium Flower Seeds, supplied as non-GMO seeds with growing information for home gardeners.
Start Growing Nasturtiums
Nasturtiums reward simple care. Give them sun, free-draining soil, moderate water, and less fertiliser than you think they need. Within weeks, the garden can be filled with edible colour, pollinator activity, and vigorous trailing growth.
Start with Nasturtium Flower Seeds – Edible, Non-GMO, then explore our full seed collection for more flowers and edible crops suited to South African gardens.