How to Grow Nasturtiums as Ground Cover: When to Plant, Best Varieties & Care Guide

Intro for growing nasturtiums as ground cover

Nasturtiums (Tropaeolum majus) make an exceptional ground cover choice for gardens, offering a cascade of bright, trumpet-shaped blooms in orange, yellow, and red hues against round, lily pad-like foliage. These easy-growing annuals not only create a vibrant carpet of color but also serve multiple garden functions—they attract pollinators, deter pests, and even provide edible flowers and leaves with a peppery taste similar to watercress. Perfect for filling bare spots, covering slopes, or spilling over garden edges, nasturtiums thrive in average to poor soil conditions across most temperate regions. Their sprawling habit, quick growth, and minimal maintenance requirements make them ideal for beginning gardeners looking to add both beauty and functionality to their landscape.

When to plant nasturtiums as ground cover

Nasturtiums perform best when planted after all danger of frost has passed and soil temperatures have reached at least 13-15°C (55-60°F). In most temperate regions, this typically falls between mid-spring and early summer. These frost-tender annuals cannot survive freezing temperatures, so timing is crucial for success. For cooler regions (UK, US Zones 3-6), wait until late spring when soil has thoroughly warmed. In warmer Mediterranean or subtropical climates (US Zones 8-10), you can plant nasturtiums in early spring or even fall for winter blooming, as mild winters won’t damage the plants. Soil temperature is more important than calendar date—cold soil will delay germination and may cause seeds to rot.

Best time to plant nasturtiums as ground cover

For cool-temperate regions (UK, northern US, Canada), plant nasturtiums between mid-May and early June when soil has reliably warmed. In moderate climates (US Zones 7-8), mid-April to mid-May provides optimal planting conditions. Warm-climate gardeners (US Zones 9-10, Mediterranean regions) can plant in March-April for spring/summer growth or August-September for fall/winter displays. Direct sowing is strongly preferred for nasturtiums as they develop long taproots that resent disturbance. If starting indoors is necessary in very short-season areas, use biodegradable pots and transplant seedlings when they have just 2-3 true leaves, typically 3-4 weeks after germination.

Best nasturtium varieties to grow as ground cover

• Tropaeolum ‘Jewel Mix’ – Semi-trailing variety (30-40cm spread) with vibrant jewel-toned flowers, perfect for smaller spaces and container edges.
• Tropaeolum ‘Gleam Mix’ – Semi-trailing hybrid with double flowers that spread 1-1.5m, offering excellent ground coverage with stronger stems.
• Tropaeolum ‘Empress of India’ – Compact but spreading variety with striking dark blue-green foliage and crimson flowers, creating dramatic contrast.
• Tropaeolum ‘Alaska’ – Features unique variegated cream-splashed foliage that brightens shady spots, spreading 60-90cm.
• Tropaeolum ‘Whirlybird’ – Semi-trailing variety with upward-facing flowers that don’t hide under foliage, making them more visible as ground cover.
• Tropaeolum minus ‘Peach Melba’ – Compact spreader with cream and raspberry-colored blooms, ideal for smaller spaces.
• Tropaeolum ‘Tip Top Apricot’ – Mounded habit with unusual soft apricot blooms held above foliage, spreading 30-45cm.

How to plant nasturtiums as ground cover

Materials needed:

• Nasturtium seeds
• Garden fork or tiller
• Rake
• Watering can with rose attachment or gentle hose nozzle
• Light mulch (optional)
• Plant markers

Step-by-step planting instructions:

1. Select a site receiving full sun to partial shade (at least 4-6 hours of direct sunlight daily).
2. Prepare the soil by loosening it to a depth of 15-20cm (6-8 inches) with a garden fork or tiller.
3. Unlike most plants, avoid amending soil with compost or fertilizer—nasturtiums bloom more profusely in lean soil.
4. Rake the area smooth, removing large stones and breaking up clumps.
5. Soak nasturtium seeds overnight to speed germination (optional but helpful).
6. Sow seeds directly 2.5cm (1 inch) deep, spacing them 20-30cm (8-12 inches) apart for trailing varieties or 15cm (6 inches) for bushier types.
7. For effective ground cover, plant in a staggered pattern rather than rows.
8. Cover seeds with soil and firm gently with your palm.
9. Water thoroughly but gently to avoid displacing seeds.
10. Mark the planted area to avoid accidental disturbance during the 7-10 day germination period.

How to grow nasturtiums as ground cover

Nasturtiums require minimal care once established. Provide full sun for best flowering, though they tolerate partial shade in hotter climates. Water moderately when the top 2.5cm (1 inch) of soil feels dry—typically once weekly in moderate climates, increasing to twice weekly during hot, dry periods. Importantly, avoid high-nitrogen fertilizers which promote lush foliage at the expense of flowers; if soil is extremely poor, apply a half-strength, low-nitrogen fertilizer (like 5-10-10) once monthly. Mulching is generally unnecessary and may promote rot in humid conditions. No staking is required for ground cover varieties, but occasional pruning helps direct growth—pinch growing tips to encourage bushier habits and remove yellowing leaves promptly. For container growing, use pots at least 30cm (12 inches) in diameter with drainage holes, and position them where trailing stems can cascade naturally.

Caring for nasturtiums as ground cover

Ongoing care for nasturtium ground cover is refreshingly simple. Deadhead spent blooms regularly to encourage continued flowering and prevent self-seeding if unwanted. Watch for aphids, which particularly favor nasturtiums—a strong spray of water often dislodges them, or introduce ladybugs as natural predators. Cabbage white butterflies may lay eggs on leaves; handpick caterpillars or use Bacillus thuringiensis as an organic control. Powdery mildew can affect plants in humid conditions—improve air circulation by thinning plants and avoid overhead watering. Harvest flowers and young leaves regularly for culinary use when fully open but still fresh, ideally in morning hours. Both flowers and leaves can be stored in the refrigerator between damp paper towels for 2-3 days, though they’re best used fresh in salads, as garnishes, or made into nasturtium butter or pesto.

Understanding bolting in nasturtiums as ground cover

Unlike many garden plants, nasturtiums don’t technically “bolt” in the traditional sense of prematurely producing seed stalks. However, they do respond to environmental stressors by shifting from vegetative growth to flowering and seed production. This natural progression accelerates during hot weather (consistently above 29°C/85°F), drought conditions, or when plants experience nutrient stress. To extend the productive period of your nasturtium ground cover, provide afternoon shade in hot climates, maintain consistent soil moisture (without overwatering), and remove spent flowers promptly. If plants begin to look leggy and produce fewer flowers by midsummer, consider a light trimming (removing up to one-third of growth) to rejuvenate them. In very hot regions, accept that nasturtiums may naturally decline during peak summer heat—plan for a second planting in late summer for fall blooming.

Why does nasturtium ground cover turn bitter?

• Heat stress – Temperatures consistently above 29°C (85°F) increase bitterness; provide afternoon shade or plant where taller plants offer protection.
• Drought – Insufficient water concentrates compounds that create bitterness; maintain even soil moisture without waterlogging.
• Plant age – Older leaves naturally develop stronger flavor; harvest young, tender growth for milder taste.
• Excessive nitrogen – High-nitrogen fertilizers can alter flavor compounds; avoid fertilizing or use only low-nitrogen formulations.
• Natural defense – Stress from pest damage triggers increased bitterness as a defense mechanism; address pest issues promptly.

Companion planting for nasturtiums as ground cover

Nasturtiums make excellent companions for numerous garden plants. Plant them around fruit trees and bushes where they attract pollinators while their strong scent confuses pests seeking fruit. Interplant with cucumbers, squash, and melons, as nasturtiums deter cucumber beetles and squash bugs. Grow them near brassicas (cabbage, broccoli, kale) where they act as trap crops for aphids and cabbage white butterflies. Roses benefit from nasturtiums’ ability to repel aphids and provide ground coverage that suppresses weeds. Tomatoes grow well with nasturtium ground cover, which helps retain soil moisture and deters whiteflies. Avoid planting nasturtiums near beans and peas, as they may compete for similar soil nutrients and potentially inhibit growth. Also, keep distance from mustard family herbs (watercress, garden cress) which can host similar pests and diseases.

Seasonal calendar

• March-April: Prepare planting area; sow seeds indoors in biodegradable pots in cold regions.
• May: Direct sow seeds in most temperate regions once soil warms; transplant indoor seedlings after last frost.
• June: Continue sowing in cooler regions; thin seedlings if needed; begin harvesting early leaves.
• July-August: Regular harvesting of flowers and leaves; monitor for pests in hot weather; provide additional water during dry spells.
• September: Continue harvesting; collect seeds from spent flowers for next year; sow fall crop in warm regions.
• October: Final harvests in most regions; allow some plants to set seed for self-sowing if desired.
• November-February: Plan next season’s planting; in frost-free regions, maintain winter-growing nasturtiums with occasional watering.

Problems & solutions

Common questions about growing nasturtiums as ground cover

How often should I water nasturtium ground cover?
Water when the top 2.5cm (1 inch) of soil feels dry—typically once weekly in moderate weather and twice weekly during hot, dry periods. Avoid overwatering, which can lead to root rot and reduced flowering.

How much sunlight do nasturtiums need to thrive as ground cover?
Nasturtiums perform best with 4-6 hours of direct sunlight daily. In hot climates (above 29°C/85°F), afternoon shade helps extend the flowering period and prevents heat stress.

Can I grow nasturtiums as ground cover in containers?
Yes, trailing varieties work beautifully in containers at least 30cm (12 inches) in diameter with good drainage. Position containers where stems can cascade over edges, and water more frequently than in-ground plantings.

How far apart should I space nasturtium seeds for effective ground cover?
Space seeds 20-30cm (8-12 inches) apart for trailing varieties or 15cm (6 inches) for bushier types. Plant in a staggered pattern rather than rows for more effective coverage.

How cold-tolerant are nasturtiums?
Nasturtiums are frost-tender annuals that will die when temperatures drop below freezing (0°C/32°F). In mild winter areas (USDA Zones 9-11), they may continue growing through winter.

How quickly will nasturtiums fill in as ground cover?
Under ideal conditions, nasturtiums germinate in 7-10 days and begin spreading within 3-4 weeks. Expect full ground coverage approximately 6-8 weeks after planting, depending on variety and spacing.

Should I fertilize my nasturtium ground cover?
Generally, no—nasturtiums flower more profusely in lean soil. If growing in extremely poor soil, apply only half-strength, low-nitrogen fertilizer (like 5-10-10) once monthly to avoid excessive leaf growth at the expense of flowers.