The Five Seeds You Can Plant Now That Will Flower in August in the UK

July might feel like it’s too late to start sowing seeds, but there are still plenty of fast-growing flowers that will bring your garden to life by August. Whether you’re hoping to fill a few gaps in your borders, brighten up patio pots, or attract pollinators, these five picks are perfect for a quick burst of summer colour.

Here’s what you can plant now for a blooming lovely display in just a few weeks.

1. Calendula (Pot Marigold)

These cheerful orange and yellow blooms grow quickly and thrive even in less-than-perfect soil. Calendula is one of the easiest flowers to grow from seed and will reward you with a profusion of daisy-like flowers from late summer into autumn.

Why now? Calendula seeds germinate fast in warm soil and will flower around six to eight weeks after sowing.
How to plant: Sow directly into well-prepared soil in full sun and thin seedlings to 20–30cm apart. Water regularly to keep them going through hot spells.
Extra bonus: Calendula attracts bees and other pollinators, making it a great addition to wildlife-friendly gardens.

2. Nasturtiums

If you’re after vibrant reds, oranges, and yellows with a trailing or climbing habit, nasturtiums are ideal. They grow rapidly and can cover unsightly fences or cascade beautifully from containers.

Why now? Nasturtiums flower within 6–8 weeks of sowing, so you can still catch a colourful display this summer.
How to plant: Sow seeds directly in sunny spots and water sparingly (they actually thrive on poor soil and don’t need fertiliser).
Extra bonus: Both the flowers and leaves are edible, adding a peppery kick to summer salads.

3. Cosmos

Cosmos are famed for their delicate, airy flowers and are one of the quickest summer blooms to grow. They’re perfect for cutting gardens and will give you armfuls of flowers well into autumn if you keep deadheading.

Why now? Choose a fast-growing variety like Cosmos bipinnatus for blooms in as little as 8 weeks.
How to plant: Sow seeds into pots now and plant them out once they’ve grown into sturdy seedlings, or sow directly in a sunny, sheltered spot.
Extra bonus: Cosmos flowers are magnets for butterflies.

4. Sweet Alyssum

For a low-growing carpet of white or pastel blooms, sweet alyssum is unbeatable. Its honey-scented flowers are perfect for edging borders, filling gaps, or trailing from containers.

Why now? Alyssum is quick to germinate and can start flowering in as little as 6–7 weeks.
How to plant: Scatter seeds on the surface of raked soil and lightly press them in. Water gently and thin seedlings if they’re overcrowded.
Extra bonus: This plant’s sweet scent will add fragrance to patios and seating areas.

5. Californian Poppies

These hardy annuals thrive in poor soil and dry conditions, making them a stress-free choice for late sowing. Their silky, vibrant flowers are perfect for wildflower-style planting.

Why now? Californian poppies can go from seed to flower in 6–8 weeks, giving you time for a bright August display.
How to plant: Scatter seeds where you want them to flower, rake in lightly, and let nature do the rest. They need very little attention once established.
Extra bonus: Once they start flowering, they’ll often self-seed for next year.

Quick Tips for Success

🌱 Choose sunny spots – most summer flowers love full sun and won’t perform well in heavy shade.
💧 Water regularly – especially during dry spells, but avoid overwatering seeds which can rot.
✂️ Deadhead spent blooms – this encourages more flowers and prolongs the display.

With these five easy flowers, you can still enjoy a riot of colour in your garden this summer. Grab a packet of seeds, and in just a few weeks, you’ll be enjoying vibrant blooms through August and beyond.