A Year-Round Native Bulb Planting Calendar for Large Projects and Net Gain Sites

Bulb planting is usually thought of as an October job. On a garden scale that is close enough. On a housing scheme, a country estate or a biodiversity net gain site, it is not. Bulbs have to be specified, ordered, stored, planted and then protected by the mowing regime, and each of those steps has its own window.

This bulb planting calendar sets out what to do and when, across the whole year, for native wildflower bulbs on larger sites. It covers the different planting windows for dry bulbs and bulbs “in the green”, how to fit bulbs around seed sowing and construction, and what to write into a long-term management plan.

It is aimed at developers, landscape architects, councils, estate managers and ecologists. For planting depths and techniques, see our practical guide to planting wildflower bulbs. For choosing species to suit your soil, see our guide to native wildflower bulbs by soil type.

Why the planting window depends on the type of bulb

Native bulbs reach you in three forms, and each has a different planting window. Getting this right is the difference between a full drift and a patchy one.

• Dry bulbs (bluebell, wild daffodil, Tenby daffodil, wild garlic, wild tulip): plant in autumn, September to November.
• Tubers and rhizomes (wood anemone, winter aconite, wild cyclamen): plant as soon as they arrive in autumn, because they dry out quickly.
• Bulbs in the green (mainly snowdrops and winter aconite): plant in late winter, just after flowering, with the leaves still on.

On a large site, these windows rarely line up neatly with the construction programme. Plan the bulb planting at the same stage as the landscape specification, not at handover.

The bulb planting calendar, season by season

The calendar below runs from the start of the year. On a new scheme, the planning tasks in spring and summer usually come before the first autumn planting.

January to March: in-the-green planting and baseline checks

• Plant snowdrops and winter aconite in the green as soon as flowering finishes, usually February into March.
• Plant in mild spells only, never into frozen or waterlogged ground.
• Record existing snowdrop, aconite and early daffodil colonies on the site while they are visible. This is useful baseline evidence for ecologists.

April and May: survey, check and protect

• Walk the site while bluebells and wild garlic are in flower. Native bluebell colonies are much easier to map in flower than in leaf.
• Note any Spanish or hybrid bluebells near planting areas, so they can be removed before native bulbs go in.
• Keep machinery and storage compounds off existing bulb colonies. Crushed leaves weaken bluebells, and recovery takes years.

June and July: let the foliage die back, then order

• Leave bulb foliage uncut until it has yellowed, usually around six weeks after flowering. This is when the bulb rebuilds its reserves.
• Take the meadow hay cut in July or later on areas with bulbs in grass.
• Place orders for autumn delivery. Large volumes of native bulbs are limited, so order early in summer.

August and September: prepare ground and plant the early starters

• Prepare planting areas: clear dense grass from bulb drifts, relieve compaction and avoid adding fertiliser.
• Plant wild daffodils and Tenby daffodils early, as they root in early autumn.
• Plant wood anemone rhizomes and wild cyclamen tubers on arrival.
• Sow wildflower seed in the same areas from mid-August, so bulbs and seed establish together.

October to December: the main dry-bulb planting

• Plant bluebells, wild garlic, snowdrops (dry), wild tulips and fritillaries through October and November.
• Plant in clusters and irregular drifts rather than even grids, for a natural look.
• Late deliveries can go in during December if the ground is workable. Store bulbs somewhere cool, dry and airy until then.

Fitting the bulb planting calendar into a construction programme

On development sites, the landscape phase is often squeezed into whatever season handover falls in. Bulbs are less forgiving than turf or containerised shrubs. Missing the autumn window usually means waiting a full year, or switching to more expensive in-the-green stock.

The practical answer is to phase the planting. Plant trees, hedges and seed in the first suitable autumn after the soil works are done. Add woodland bulbs once hedgerows and tree belts are established enough to give some late-spring shade. Plant grassland species such as wild daffodils into the meadow areas in the first or second autumn, once the sward has started to settle.

Retained woodland and old hedgerows are the easiest win. Their soils already suit woodland bulbs, and enhancing their ground flora is often a straightforward part of the habitat management plan.

Quantities, spacing and drift design

On a large site, the temptation is to spread a fixed number of bulbs evenly across every planted area. The result is a thin scatter that looks like nothing in particular. It is better to plant fewer, denser drifts in the places people will see them, and let them spread.

As a starting point, plant wild daffodils at roughly 10 to 20 bulbs per square metre within a drift, and smaller bulbs such as bluebells and snowdrops at 25 to 50. Vary the density, thinning out towards the edges, so drifts fade naturally into the surrounding grass or woodland floor.

Concentrate effort along paths, entrances, woodland edges and the views from homes or offices. Those are the places where a bulb planting earns its keep with residents and visitors, and where it will be noticed if it is mown at the wrong time.

Storing and handling bulbs on site

Large deliveries rarely go straight into the ground. Weather, site access and other trades all get in the way, and bulbs are living material that deteriorates in poor storage.

• Unpack on arrival and check for soft, mouldy or shrivelled bulbs.
• Store dry bulbs somewhere cool, dry and well ventilated, in open crates or net sacks, never in sealed bags.
• Plant tubers and rhizomes within days, as they dry out much faster than true bulbs.
• Keep in-the-green stock damp and shaded, and plant it within a few days.

Brief the planting team on species and drift layout before they start. A bag of bluebells planted in full sun on an open bank is a common and avoidable waste.

Biodiversity net gain bulbs: what they can and cannot do

In England, mandatory biodiversity net gain has applied to major development since February 2024 and to small sites since April 2024. Developers must show at least a 10% gain in biodiversity units using the statutory metric, and secure the habitat’s management for a minimum of 30 years.

Units are calculated from habitat type, area and condition. Planting bulbs does not create a new habitat type, so bulbs on their own do not generate units. Where they help is in reaching and holding the target condition of woodland, hedgerow and grassland habitats that are counted, and in delivering the early-season flowers pollinators need.

In Wales, there is no statutory metric. Planning Policy Wales asks every development to deliver a net benefit for biodiversity, and native ground flora in retained and new woodland is a natural part of that case.

• Name native species by Latin name in the landscape and ecological management plans.
• Record where bulbs are sourced, using cultivated, not wild-collected, stock.
• Write the mowing and grazing restrictions into the 30-year management plan.
• Include spring monitoring visits, timed for flowering, in the plan.

Common bulb planting calendar mistakes

Most problems with bulbs on larger sites come from timing rather than technique.

• Ordering in October for October planting, when native stock has already sold out.
• Leaving bulbs in a site cabin over winter and planting them dried out in spring.
• Planting snowdrops as dry bulbs in autumn when in-the-green stock would establish better.
• Handing over a maintenance plan with a spring mowing regime that cuts bulb foliage.

Managing bulbs year after year

Most failed bulb plantings on public and commercial land are not planting failures. They are mowing failures. Contractors cut on a fixed schedule, and bulb foliage goes in April before it has done its work.

For bulbs in grass, set an exclusion zone with no cut until late June or early July, then take a hay cut and remove the cuttings. On amenity land, mark bulb drifts on the maintenance plan so they are not cut with the surrounding lawn. On floodplain meadows with fritillaries, avoid spring grazing entirely.

Expect a modest first spring, particularly from bluebells and wood anemone. Colonies build over three to five years, and a well-managed native planting should keep spreading for decades. In winter, use the quiet months to check drifts for damage and plan any top-up planting.

Bulbs and seed from Wildahome

Our spring bulbs range includes native Bluebell, Wild Daffodil, Tenby Daffodil, Wild Garlic and Wood Anemone, with Snowdrops and Winter Aconite for estate and amenity settings. The Woodland Wildflower Bulb Collection gives a ready-made mix for woodland edges.

For larger schemes, we supply bulbs and wildflower seed together, matched to the same zones and programmed so both go in during the same autumn window.

Programming bulbs into your scheme

If you are planning a housing scheme, public space or net gain site, send us the landscape plan and your programme. We will suggest native species, quantities and planting windows for each phase, and quote for bulbs and seed together. See also our guide to large-scale wildflower projects for the wider planning steps.

Frequently Asked Questions

When is the best time to plant native bulbs on a large site?

Plant dry bulbs such as bluebells and wild garlic from September to November, with daffodils early in that window. Plant snowdrops and winter aconite in the green in February and March, just after flowering. Order in early summer, as large volumes of native bulbs are limited.

What does planting bulbs in the green mean?

Planting in the green means planting bulbs just after they have flowered, with their leaves still attached. It is mainly used for snowdrops and winter aconite, which establish more reliably this way than from dry bulbs. The usual window is February to March.

Can you plant bulbs in December?

Yes, if the ground is not frozen or waterlogged. Late planting is better than storing bulbs until spring, when they will have dried out. Keep them cool, dry and well ventilated until you can plant, and expect a slightly later or weaker first flowering.

Do bulbs count towards biodiversity net gain?

Not directly. Biodiversity net gain is measured in habitat units based on habitat type, area and condition. Native bulbs do not create a habitat on their own, but they can help woodland, hedgerow and grassland habitats meet their condition targets under a 30-year management plan.

When can you mow bulbs in grass?

Wait until the foliage has turned yellow, usually around six weeks after flowering. In practice that means no cutting until late June or early July in most areas with spring bulbs. Cutting earlier starves the bulbs and the display declines within a few years.

How should a bulb planting calendar fit with wildflower seed sowing?

They overlap well. Sow wildflower seed from mid-August to late October and plant dry bulbs from September to November, so both can go into the same prepared ground in one autumn. Plant bulbs first or alongside sowing, then roll or tread the surface.

How many years do native bulbs take to establish?

Expect three to five years for a planting to settle. Bluebells and wood anemone are slow: the first spring is often sparse, and colonies thicken each year as bulbs and rhizomes multiply. Daffodils usually flower well from the first spring.