When to Plant Nasturtium Seeds in the UK

Knowing when to plant nasturtium seeds in the UK is key to growing strong plants and enjoying months of colourful, edible flowers. Nasturtiums are quick-growing annuals, but they are frost tender, so planting them at the right time makes all the difference.

This guide explains the best time to plant nasturtium seeds in the UK, whether you start them indoors or plant them directly outside.

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Nasturtiums are cheerful, edible flowers with bright colours and peppery taste — easy to grow in beds, containers, and hanging baskets.

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• Nasturtium Plug Plants / Young Seedlings
Healthy young nasturtium plants ready to transplant into borders or containers for instant summer colour.
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Light, nutrient-balanced compost ideal for nurturing nasturtium roots and encouraging healthy growth.
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Best Time to Plant Nasturtium Seeds in the UK

In the UK, nasturtium seeds are best planted in spring, once temperatures begin to rise.

Recommended planting times:

• Indoors: March to April
• Outdoors: Late April to May
• Flowering: June to October

Outdoor planting should only be done once the risk of frost has passed, as cold conditions can damage seedlings or cause seeds to rot.

Planting Nasturtium Seeds Indoors

Planting nasturtium seeds indoors gives them a head start and can lead to earlier flowers.

When to plant indoors:

• Mid-March to April

How to plant indoors:

• Sow one seed per pot
• Plant seeds about 2cm deep
• Keep in a bright, frost-free place

Nasturtiums dislike root disturbance, so individual pots work best. Harden plants off gradually before moving them outside.

Planting Nasturtium Seeds Outdoors

Direct planting is simple and works very well in UK gardens once the soil has warmed.

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March is when the growing season truly begins. Seeds are being sown daily, beds are prepared and late frosts are still possible — these essentials help produce strong plants and a successful start.

Seed Trays, Modules & Propagation Kits — perfect for tomatoes, brassicas, lettuce, onions and flowers. 👉 Click here to see top options

Heated Propagators, Heat Mats & Grow Lights — improves germination and prevents leggy seedlings during cold nights. 👉 Click here to see top options

Seed & Cutting Compost — essential for healthy seedlings and strong root growth. 👉 Click here to see top options

Garden Fleece & Plant Protection Covers — protects seedlings, potatoes and early plantings from late frost. 👉 Click here to see top options

Spring Vegetable Seeds — carrots, beetroot, peas, spinach and salads can all be started now. 👉 Click here to see top options

Garden Kneeler & Seat — makes long sowing and planting sessions far more comfortable. 👉 Click here to see top options

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When to plant outdoors:

• Late April to May
• After the last frost
• When soil feels warm and is not waterlogged

Cold, wet soil can delay germination or cause seeds to fail, so patience is important.

Can You Plant Nasturtium Seeds Too Early in the UK?

Yes. Early planting is a common mistake.

Problems caused by planting too early include:

• Poor germination
• Seed rot in cold soil
• Frost-damaged seedlings
• Slow, weak growth

It’s always better to wait an extra week than plant too soon.

Regional Differences Across the UK

Planting times can vary slightly depending on location.

• Southern UK: Late April is often suitable
• Midlands & Northern England: Late April to early May
• Scotland & higher ground: May is safest

Local weather conditions are more important than calendar dates.

Can You Plant Nasturtium Seeds Later?

Yes. Nasturtiums are very forgiving.

• Seeds planted in June will still flower
• Warm soil speeds up germination
• Later planting can extend flowering into autumn

This makes nasturtiums ideal for staggered planting.

Final Thoughts: When to Plant Nasturtium Seeds in the UK

In the UK, the best time to plant nasturtium seeds is March to April indoors or late April to May outdoors, once frost risk has passed and the soil has warmed. Waiting for the right conditions results in healthier plants, better flowering, and fewer problems.

Easy to grow and fast to establish, nasturtiums reward patient spring planting with vibrant colour and edible harvests.

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