The 7 best flowers to sow in March

Between drizzle, late frosts and the first rays of sunshine, March brings a surprisingly important choice: which flowers to sow. Choose suitable varieties now and raise them under cover, and from June you can enjoy a blaze of colour that lasts into autumn – without having to work constantly in the borders.

Why March determines your summer garden

As daylight hours increase, many amateur gardeners are eager to get started. The garden may still look wintery above ground, but the season is already beginning beneath the surface. This is the opportunity: flowers sown early establish strong roots and gain a clear head start.

“Sowing in March brings the flowering period forward – the summer garden begins earlier and keeps going for longer.”

There is one catch: this month remains unpredictable. Night frosts are still possible in many areas until April. For that reason, experienced gardeners start their plants in a sheltered place:

• on a bright windowsill
• in a simple plastic greenhouse
• in a well-protected, bright garage or shed with a window
• in an unheated conservatory

This lets young plants grow steadily yet sturdily before moving into the border after the final frosts. With good planning, they will later fill every gap that might otherwise show bare soil.

Choosing seeds wisely

Many gardeners will recognise the situation: you buy seed packets, sow them with care and water them – only to end up with a handful of feeble seedlings. This is often not down to a supposed lack of gardening skill, but simply to the seeds themselves.

For this reason, increasing numbers of amateur gardeners choose open-pollinated seed that can be saved and resown. Seeds collected from their own plants can be used to grow new flowers the following year. It saves money and reduces reliance on each season’s offers at the garden centre.

There is another benefit: plants whose seed is collected in the same garden year after year gradually adapt to that location. Many observers say that these flowers appear tougher, more resilient and more vigorous.

Anyone keen to exchange seeds can look for local seed-swapping events. Libraries, community gardens and environmental groups often run small “seed libraries”, where you can donate your own seeds and take home new treasures.

The 7 best flowers to sow in March

With the following seven varieties, even an unremarkable border can become a ribbon of flowers that lasts throughout summer. All are considered relatively straightforward and are well suited to beginners.

Zinnias – bold, long-flowering colour

Zinnias are a classic choice for richly planted summer borders. Their vibrant shades range from brilliant pink and orange-red to bicoloured blooms. These plants thrive in warmth and full sun.

• Sowing: indoors from March; directly into the border from May
• Position: sunny and sheltered from wind
• Key benefit: perfect for colourful summer bouquets

Cutting away faded flower heads regularly encourages an ongoing supply of new buds.

Sweet peas – fragrant climbers for fences and balconies

Annual sweet peas create a summery mood through both their appearance and their scent. Their delicate pink, violet or white flowers climb up trellises, fences and balcony railings.

Starting a few seeds in pots in March produces lush climbing plants later in the season. Their roots are sensitive, so it is best to sow them in individual pots and plant them carefully with the entire root ball intact.

Nasturtiums – attractive, low-maintenance and edible

Nasturtiums are true all-rounders for the summer garden. Depending on the variety, they either spread as ground cover or climb along fences. Their glowing yellow, orange and red flowers bring life to both the border and the kitchen.

“The flowers and young leaves have a gently peppery flavour and are perfect in summer salads or on a slice of bread and butter.”

They can be sown successfully in pots or straight into the border. In cooler regions, starting them indoors is worthwhile so that the plants are already growing strongly by June.

Wallflowers (sweet alyssum and relatives) – old-fashioned garden charm

Strongly scented plants are currently enjoying a revival. Varieties from the traditional wallflower group recall old cottage gardens with their fragrance. They work beautifully at the edge of patios, beside paths or in mixed perennial borders.

Sow them in March for compact plants with richly coloured flowers and a pleasant scent – ideal for anyone who likes to sit in the garden for a while in the evening.

Coreopsis – patches of sunshine for the border

Coreopsis, often known as tickseed, creates bright highlights with yellow to orange flowers. The plants produce abundant blooms and look like little spots of sunshine in a border.

• Sowing: indoors in March; outdoors from May
• Especially suitable for: border edges and naturalistic planting schemes

Leaving the seed heads in place provides birds with an extra food source in late summer.

Nigella (love-in-a-mist) – delicate and romantic

With its finely divided foliage and slightly dreamy flowers, nigella looks as though it belongs in a nostalgic gardening book. It is not only attractive in a border: its decorative seed pods can also be used in dried arrangements.

Sowing is uncomplicated: scatter the fine seeds in trays in March or directly into the border in mild regions, press them down lightly, and that is all that is needed.

Papaver (poppies) – a wildflower meadow in no time

A patch of flowering poppies instantly gives a garden the appearance of a small wildflower meadow. Individual delicate blooms last only a few days, but a steady succession of buds continually adds fresh splashes of colour.

“Many poppy varieties self-seed – let them do so and you will have new surprises in the border every year.”

In cold regions, raising plants in pots first gives them a head start. In sheltered, milder locations, direct sowing from March or April is often sufficient.

How to grow sturdy young plants from seed

For March sowing to be a real success, a few basic principles matter more than expensive equipment:

• Loose growing medium: Special seed compost or a blend of potting compost and sand allows fine roots to develop well.
• Light without intense heat: Bright windows are ideal. Seedlings can scorch in sunshine directly behind south-facing windows.
• Water moderately: Compost should be moist rather than wet. Waterlogging quickly leads to fungal problems.
• Prick out seedlings: Once plants have developed several leaves, move them into individual pots. This helps them become strong, separate plants.

After the last frosts, it is time to harden them off. Put the young plants outside for a few hours at a time during the day, initially in a place protected from the wind. This acclimatises them to sunlight and fluctuating temperatures.

What these flowers also contribute to the border

As well as looking attractive, many of these species offer further advantages:

• Nasturtiums attract aphids, helping to keep them away from more sensitive vegetables.
• Flower-rich varieties such as zinnias and coreopsis are real insect magnets and support wild bees.
• Self-seeding species such as poppies and nigella produce new plants every year without extra work.

Combined thoughtfully, these flowers do more than fill borders with colour: they create a small ecosystem. Tall zinnias, climbing sweet peas and ground-covering nasturtiums form lively structures that also cope better with dry spells.

It is useful to view the seeds for these seven flowers as a personal “basic package”. A few seed packets in March are enough to plant up window boxes, containers and several borders. What begins as an initially unremarkable selection becomes a summer garden that looks as though it was planned by a professional – even though it all started with a few inconspicuous seeds in the still-cool March weather.