Flowering Bulbs in August
August sits at a turning point in the bulb calendar. Summer is winding down and the soil is still warm, which makes it one of the best times to plant spring-flowering hardy bulbs that need a long establishment period before they bloom. Snowdrops planted now will reward you with early-spring flowers from January onwards. Iris reticulata and Dutch iris go in now for late winter and early spring colour. Woodland plants like trillium and Mertensia virginica need to be planted while they are dormant in late summer to settle in before the growing season begins.
Quick wins in August:
- Prime time to plant snowdrops (Galanthus) for late winter flowers from January to March
- Best month to get Iris reticulata and Dutch iris in the ground for late winter and early spring colour
- Right window to plant woodland rhizomes like trillium and Mertensia virginica while dormant
- Warm soil still supports fast root establishment before temperatures drop
- Last chance to fill gaps in borders and containers before the main autumn rush
What Bulbs Can You Plant in August?
August is primarily a spring-bulb planting month. The varieties listed here are mostly dormant now and ready to go straight in the ground, where they’ll spend autumn and winter quietly establishing before pushing up growth in late winter or spring.
In August, look out for bulbs that:
- Are classified as autumn-planting or summer-planting (check each product page)
- Flower in late winter, spring, or early summer
- Suit well drained soil or containers with good drainage, particularly iris and snowdrop varieties
- Match your light levels, whether full sun, partial shade, or shade
Top 5 Bulbs for August Planting
- Galanthus (Snowdrops): August is one of the best times to plant snowdrops as dry bulbs, while they are fully dormant. They establish well in warm soil and will produce their nodding white flowers from January to March the following year. Plant in partial shade or dappled light with reliably moist, humus-rich soil. Clumps naturalise and improve year on year.
- Iris reticulata: These small, early-flowering bulbous irises go in during late summer for late winter and early spring blooms, often appearing alongside snowdrops in February and March. Plant in full sun with very well drained soil or in pots with gritty compost. They are compact, hardy, and produce richly coloured flowers depending on the variety.
- Dutch Iris: Larger than Iris reticulata, Dutch iris are planted in late summer for early summer flowers the following year. They produce tall, elegant stems with showy blooms in a wide range of colours. Plant in full sun in well drained soil at around 10-15cm depth.
- Trillium: These woodland rhizomes go in during late summer while dormant and produce distinctive three-petalled flowers in mid to late spring. They need partial to full shade with moist, humus-rich soil and plenty of organic matter. Slow to establish but long-lived and rewarding once settled.
- Mertensia virginica (Virginian Bluebells): Plant these dormant rhizomes in August in a shaded or partially shaded spot with reliably moist, fertile soil. They die back completely in summer, so August is the right time to put them in. Clusters of nodding, tubular blue flowers appear in mid spring, and the plant disappears again by early summer. A genuinely useful gap-filler for shaded borders.
Planting Tips for August Bulbs
August planting is straightforward but the soil can be dry after summer, so there are a couple of things worth keeping in mind.
Water in well and keep moisture consistent: Newly planted bulbs and rhizomes need moisture to start forming roots, especially trillium and Mertensia which prefer moist conditions. Water after planting and check containers and raised beds regularly, as these dry out faster than open borders.
Good drainage matters for iris: Iris reticulata and Dutch iris are prone to rot in wet or poorly drained soil. Work grit into heavy ground or plant in pots with a gritty, free-draining compost mix to prevent rot.
Plant snowdrops at the right depth: Galanthus bulbs should be planted roughly three times their own depth, usually around 7-10cm. In heavy soil, add a little grit to the planting hole to improve drainage and help prevent rot.
Give trilliums a shaded spot with rich soil: Trilliums need organic matter, consistent moisture, and shade. They are slow to establish and dislike disturbance, so choose the planting position carefully before you put them in.
Don't let rhizomes dry out in storage: Trillium and Mertensia rhizomes can dry out quickly once lifted. Plant them as soon as possible after they arrive, and if you need to store them briefly, keep them in slightly damp compost or bark in a cool, shaded spot.
Aftercare Made Simple
August-planted spring bulbs need very little attention once in the ground. The main job is keeping soil moisture consistent through any dry spells, particularly for woodland varieties like trillium and Mertensia which need moist conditions to get roots established.
For snowdrops and iris, minimal watering is needed once planted in well drained soil. Let them settle through autumn and winter without disturbance. Do not cut back any foliage that appears; allow it to die back naturally so the bulbs can build energy for the following year's flowers.
For trilliums, aftercare at planting time is minimal. Resist the temptation to dig them up if nothing appears in the first season; they can take a full year to show any growth above ground. Once established, leave clumps alone and top-dress with leaf mould or compost in autumn.
Frequently Asked Questions
Is August too late to plant spring bulbs?
Not at all. August is actually the ideal time for several spring-flowering varieties, particularly snowdrops, Iris reticulata, and woodland plants like trillium and Mertensia. They are dormant now and go in best while the soil is still warm.
What spring bulbs can I plant in August?
August suits snowdrops (Galanthus), Iris reticulata, Dutch iris, trilliums, and Mertensia virginica particularly well. All of these are either at their planting peak or approaching it during August.
What is the best soil for autumn flowering bulbs?
It depends on the variety. Nerines need very well drained soil in a warm, sheltered spot, ideally against a south-facing wall, and perform poorly in cold, wet ground. Colchicums are more tolerant but still prefer well drained soil in sun or light shade. Cyclamen coum and hederifolium both do well in dry, partially shaded spots with good drainage and a little organic matter worked in. If your garden soil is dense or waterlogged, pots and raised beds give you more control and tend to produce better results with all of these.
Do snowdrops planted in August flower the same winter?
Sometimes, yes. Snowdrops planted in August or early September can produce flowers in their first winter, particularly if the bulbs are healthy and conditions suit them. Establishing them early gives the best chance of flowers from January onwards.
Do trilliums need to be lifted in winter?
No. Trilliums are fully hardy in most UK gardens and should be left undisturbed year round. They die back completely after flowering and show no growth above ground in summer, which is normal. Lifting and replanting is likely to set them back and delay flowering.
