September
In collaboration with Charlie Harpur
September Growing Guide – Charlie Harpur
At Knepp Wildland, September is one of the most rewarding months. The air is fresh, the light softens and the whole landscape feels alive with fruit, seed and movement. My work here is all about rewilding – working with nature to create a garden that is full of life, resilient, and beautiful. This September growing guide is about striking that fine balance: harvesting what we need, guiding the garden with a light touch and leaving plenty for the wild residents that call Knepp home.
Image: Knepp Wildland
Hedgerow care
Hedges at Knepp are vital corridors for wildlife, so we cut them just once a year and only after the bird nesting season (March – August) has finished. In September we trim back our beech and other hedges – not to rigid, or formal shapes, but into soft, organic lines. This keeps them dense and healthy while still providing cover and food for birds and insects.
Bulb orders
September is also the month we plan our bulb orders for the walled garden. Our choices are guided as much by ecology as by design – we want bulbs that extend the season of nectar and pollen for pollinators, as well as bringing joy to visitors. This year we’ll be adding narcissus, cyclamen, iris, muscari, scilla and allium. We’ve learned over the years which bulbs the voles leave alone, so we stick with those – rewilding means working with what’s here, not fighting against it.
Image: Knepp Wildland
Harvesting highlights
The orchards are alive with fruit and buzzing with life. We’re picking plums, damsons, gages, apples and pears. Much of the harvest becomes organic juice for the Wilding Kitchen. What we can’t reach, we leave – along with windfalls – for birds, badgers and insects to enjoy. A rewilded orchard is as much about feeding the ecosystem as it is about feeding ourselves.
Seeds – collecting & sowing
Seeds are the lifeblood of rewilding and September is a month full of potential. At Knepp we:
- Collect perennial seed from the walled garden to propagate.
- Scatter seedheads to mimic natural dispersal and encourage natural regeneration.
- Leave plenty for birds and small mammals to feast on over winter.
Image: Knepp Wildland
It’s also still warm enough to sow:
August isn’t just about picking—it’s also a crucial time to maintain plants and prepare for the seasons ahead.
- Late vegetable crops like spinach, salad leaves, and hardy brassicas.
- Autumn annuals such as poppies and cornflowers, which root in now and leap into growth come spring.
Cues to care
A rewilded garden isn’t a free for all – it still needs thoughtful editing. September is when we gently intervene to keep balance. We graze (weed) ruderals that would otherwise dominate, rake paths and pile the fallen organic matter into habitat heaps and build features like dead hedges and log stacks.
These are what Joan Nassauer calls ‘cues to care’ – visual signals that show this isn’t neglect but intentional stewardship. Visitors see that the wildness is purposeful, not abandoned, which helps them connect with the space.
Image: Knepp Wildland
Wild lawns & grassland
This is the time to boost diversity in wild lawns and meadows. Sow a mix that includes yellow rattle to reduce grass vigour, or strew species-rich green hay from a local meadow. Leave it on the surface for a fortnight to let the seeds ripen and drop before removing.
Cuttings
We also take semi-ripe cuttings now from herbs such as sage, rosemary and thyme. They go straight into an outdoor sand frame, where they root quietly over winter. Next year we have a new generation of plants ready to join the garden.
Image: Knepp Wildland
Final thoughts
September at Knepp is about cooperation, not control. We harvest, sow, trim, and tidy – but always with the bigger picture in mind. Every pile of sticks, every patch of seedheads left standing, every hedge shaped softly rather than sharply is a small act of rewilding. It’s a month for shaping a garden that supports life in all its forms.
About the author
Charlie was our guest speaker at our Annual Lecture 2025 – a fascinating discussion on rewilding and how it shapes the work at Knepp. Charlie Harpur is Head Gardener at Knepp Wildland, one of the UK’s most influential rewilding projects. He creates spaces rich in biodiversity and beauty, showing how gardens can be places where people and nature thrive together. Knepp is open to visitors, with guided tours and self-led walks offering a chance to see wildlife, habitats, and people coexisting in a thriving landscape.
Where to find out more
Instagram: @charlie.harpur
www.knepp.co.uk
September brings a golden shift in the garden, alive with fruit, seed and movement. This month we work with rewilding in mind – trimming hedges softly after nesting, scattering seedheads and leaving plenty for birds and insects. Bulbs are ordered for spring pollinators, late salads and hardy annuals are sown, and herbs are taken as cuttings to root over winter. Each small act strikes a balance between harvest and habitat, keeping the garden full of life as autumn takes hold.
FAQs: September Growing Guide
September is where the garden shifts from active growth into a more reflective phase. You’re no longer pushing for productivity in the same way, you’re observing what’s been produced and deciding how to respond.
In a rewilded setting, that means working with what’s there rather than trying to control it. Some crops are harvested, others are deliberately left behind, and that balance helps maintain both productivity and biodiversity. It’s a month where small decisions have a lasting impact on how the garden carries into autumn and beyond.
In a rewilded garden, leaving fruit and seedheads isn’t an afterthought, it’s part of how the system functions. As natural food sources begin to decline, these become essential for birds, insects, and small mammals.
It also allows plants to complete their lifecycle. By letting seedheads remain, you encourage natural regeneration rather than relying entirely on planned planting. Over time, this creates a garden that is better adapted to its environment and less dependent on constant intervention.
Hedge cutting is one of those tasks where timing makes all the difference. During spring and early summer, hedges are often full of nesting birds, so cutting too early can disrupt breeding and reduce habitat.
By September, the nesting season has passed, making it a safer time to trim. Even then, the approach tends to be softer and less formal. The aim isn’t to impose shape, but to keep the hedge healthy while preserving its role as shelter and food source.
September offers a rare window where both collecting and sowing can happen side by side. Mature plants are producing viable seed, while soil still holds enough warmth to support germination.
At this stage, the focus is on working with what the garden is already offering. You might collect seed from plants that have performed well, while also sowing crops that benefit from early establishment.
Typical options include:
- late vegetable crops such as spinach and salad leaves
- hardy brassicas that can establish before winter
- autumn annuals like poppies and cornflowers
This overlap is what makes September so productive, even as the season begins to slow.
Autumn is when bulb decisions are made with the next season in mind. Rather than choosing purely on appearance, the focus often shifts towards how bulbs fit into the wider ecosystem.
That might mean selecting varieties that:
- provide early nectar for pollinators
- are less likely to be eaten by pests
- return reliably year after year
Planning at this stage gives you time to choose properly and plant at the right moment, rather than rushing decisions later on.
One of the challenges with rewilded spaces is perception. Without obvious structure, they can easily be mistaken for neglected or unmanaged areas.
“Cues to care” are small, intentional actions that signal the opposite. Maintained paths, thoughtfully shaped hedges, or deliberate habitat features all show that the space is being actively looked after.
These cues don’t reduce the wildness of the garden, they help people understand it. That balance is key in making naturalistic gardening both effective and accessible.
Improving biodiversity isn’t about completely replacing what’s there, it’s about gradually shifting the balance so more species can establish.
In September, this often involves introducing plants that naturally reduce dominant grasses and create space for others to grow. Over time, this leads to a more varied and resilient mix.
Common approaches include:
- introducing yellow rattle to weaken vigorous grasses
- spreading species-rich hay from established meadows
- allowing seeds to settle and establish naturally
It’s a slower process, but one that builds long-term stability rather than quick results.
At this point in the season, many herbs are producing semi-ripe growth, which is ideal for propagation. The material is firm enough to be stable, but still active enough to root successfully.
Taking cuttings now allows them to establish gradually over winter, without the pressure of rapid growth. By spring, they’re already rooted and ready to develop, giving you a strong, reliable set of new plants for the year ahead.
