Don't miss your chance to plant these 5 biennials before the end of July

Sow these easy-to-grow favourites now for a stunning display of blooms in spring and summer

By Eve SmallmanPublished: 25 July 2026

flowerbed of sweet william flowers with pink, red, and white blooms

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Looking ahead to next year's garden? Now is the perfect time to sow biennials before it's too late, including forget-me-nots and foxgloves.

These plants spend their first year producing roots and leafy growth, before bursting into flower in their second season. The warm soil and long daylight hours of July help young plants establish quickly before winter, setting them up for a strong display the following year.

From cottage garden classics to elegant climbers, these are the best ones to sow this month.

Forget-me-nots

a field of blue forget me not flowers in bloom.

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Eye-catching and vibrant, forget-me-nots are perfect for weaving soft blue flowers through borders and beneath spring-flowering bulbs.

'I always reach for forget-me-nots, as they bring such a soft, romantic feel to the borders,' says Natalie Dejahang, designer and co-founder of Crown Pavilions. ‘They're easy to grow, lovely for filling those little gaps, and they sit beautifully amongst roses and spring bulbs.’

Forget-me-nots grow happily in sun or partial shade and are easy to establish from seed. Ensure the soil is lightly moist while seedlings develop, and allow some plants to self-seed if you'd like natural drifts to appear.

Dame's rocket

a close up view of purple dame rocket with a green background

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With its fragrant flowers and ability to attract bees and butterflies, dame's rocket is a beautiful addition to wildlife-friendly gardens.

'The showy flowers can be white, lavender pink, or purple with four petals, providing weeks of cheerful blooms from May to July,’ says Marina Prokaten, plant expert at Plantum. ‘Plus, the fragrance is sweet and most pronounced in the evening.'

Choose a position in full sun or partial shade with moist, well-drained soil, then water during prolonged dry spells to keep the soil evenly moist. Once established, dame's rocket requires very little maintenance.

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Honesty

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Best known for its shimmering, translucent seed pods, honesty is just as beautiful in flower as it is later in the season.

‘This is a proud tall plant covered with broad, pointed, serrated leaves and violet to white showy flowers,’ explains Marina. ‘The name “honesty” was attributed to this plant because of its translucent silicles – as they resemble coins, this plant is commonly thought of as a good luck charm that attracts wealth.'

Sow seeds into rich soil and keep the ground consistently moist during the growing season. Honesty grows well in both sun and partial shade – although plants appreciate a little afternoon shade in particularly hot gardens.

Sweet William

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With its colourful flower clusters, sweet William is one of the best biennials to sow before July comes to an end.

'Planting now means the plants will have enough time to establish strong roots and foliage before winter,' says Richard Barker, horticultural expert and commercial director of LBS Horticulture. 'By the time winter arrives, seedlings will be robust enough to cope with freezing temperatures and can emerge stronger in the next season.'

Sow seeds in trays or directly into finely prepared soil in a sunny or partially shaded spot. Make sure to water the soil regularly while seedlings establish, then transplant young plants into their final position in early autumn.

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Foxgloves

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Few plants create as much impact as foxgloves, with their towering flower spikes bringing height, colour and pollinator-friendly blooms to borders.

‘Foxgloves are one of the most rewarding plants you can grow because they allow you to become a plant breeder without even trying, and are stunning plants which attract plenty of pollinators to support the rest of your garden,’ says Calogero Scannella, managing director of CS Gardens.

It’s best to sow a mixed batch of foxglove seeds together, rather than sticking to a single variety grown separately, as you’ll get all sorts of subtle differences in height, flower colour, and vigour.

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