September is the ideal time to plant ground cover (Image: Getty)
September is the sweet spot for covering bare soil. The ground is warm, rain returns, and container-grown plants establish quickly before winter. Low growers knit together to suppress weeds, conserve moisture and give a year-round polish with minimal fuss.
Why September works
Ground cover planted now benefits from active root growth, shorter stress periods and fewer watering demands. It also fills gaps before winter, protecting soil, reducing weed germination and sheltering beneficial insects. In milder areas, you can continue planting into early October if the soil remains workable.
Read more: 3 plants that thrive in September to give you the best crops in autumn
Read more: Popular plant that ‘smells beautiful’ also repels spiders
Hedera helix ‘Glacier’ hugs the ground with variegated leaves (Image: Getty)
Choose and prepare the spot:
Match plants to sun or shade and note how dry the soil becomes. Clear perennial weeds, lifting out the roots, then work in some peat-free garden compost. Set the plants so they will meet within a season or two, watering in well, and finish with a light mulch to settle the soil. Add a porous edging or stone to define paths and keep the spread in check.
Evergreen backbone
Hedera helix ‘Glacier’ hugs the ground with variegated leaves. Interest now includes late flowers rich in nectar for pollinators. Plant now in sun or shade on well-drained soil and trim shoots to keep it prostrate. Euonymus fortunei ‘Emerald Gaiety’ forms neat, variegated mats that clip cleanly. Plant now for reliable, low-maintenance cover and winter brightness.
Hypericum calycinum still opens golden saucers into September (Image: Getty)
In bloom this month:
Hypericum calycinum still opens golden saucers into September. Plant now in sun or part shade and trim after flowering to keep it compact. Geranium ‘Rozanne’ sprawls gently and flowers from summer into autumn. Plant now for quick cover next year and a late pop of colour now. Persicaria affinis ‘Superba’ carries spires of pink flowers through September. Interest now with blooms deepening to crimson and bronzed foliage. Plant now in sun or partial shade.
Shade specialists
Pachysandra terminalis forms a dense, glossy evergreen carpet in partial to deep shade. Plant now beneath shrubs and along paths for dependable, weed-smothering cover. Vinca minor, neater than Vinca major, also thrives in shade and will tolerate sun if the soil stays moist. Plant now and trim any wandering runners to keep edges tidy. Expect the main flush of violet-blue flowers in spring, with occasional top-ups later.
Touch and aroma
Stachys byzantina ‘Silver Carpet’ offers soft, silvery, velvety leaves that invite touch. Plant now in full sun on free-draining soil and protect from excessive winter wet. Creeping thyme, such as Thymus serpyllum, knits tightly between paving, releases scent when lightly trodden and copes with light foot traffic. Plant now in a sunny, well-drained spot.
Practical notes
September suits planting container-grown ground cover. Water new additions in dry spells and keep mulch off crowns to prevent rot. Tuck in autumn bulbs between new plants for spring colour. Check local guidance before planting cotoneasters near wild spaces, and choose named, garden-friendly selections for urban plots.
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Top 5 Gardening Jobs
1. Buy autumn-planting onion sets now and plant from mid to late September in sunny, well-drained soil. Space 10-15 cm apart in rows 25-30 cm, with tips just showing. Water in and net to deter birds. Reliable choices include ‘Shakespeare’ and ‘Snowball’. Learn how at my YouTube channel, @daviddomoney.
2. As days shorten, begin easing back watering for containers and greenhouse crops. Check the soil first and water only when the top couple of centimetres feel dry. Water in the morning and empty saucers after 30 minutes. Reduce feeding, but keep newly planted trees, shrubs, and perennials watered until autumn rains are reliable.
3. Harvest the last cucumbers while nights remain mild. Pick regularly to keep the flavour and prevent seeds from developing. Remove old or mildewed leaves to improve airflow and pinch off new flowers so plants focus on ripening existing fruits. Clear vines once production tails off and clean the greenhouse before the next crop.
4. Scarify and aerate lawns to refresh tired turf. Rake out thatch with a spring-tine rake or a scarifier on a high setting. Spike compacted areas or hollow-tine with a lawn aerator such as the Ames Lawn Aerator in Stainless Steel, then top-dress with sand, overseed bare patches, feed with an autumn lawn fertiliser and water lightly.
5. Trim hedges now that the main bird nesting season has passed, but always check for active nests before you cut. Work on a dry day with sharp, clean blades and shape hedges wider at the base than the top. Avoid cutting into brown wood on conifers. Gather clippings and compost healthy material.
Focus Plant: Salvia
Salvias light up September, flowering as many borders fade. Spikes and whorls of bloom add movement and late nectar, keeping bees busy.
This month is peak display and a good time to plant container-grown salvias while the soil stays warm. For bold height and deep colour, try Salvia ‘Amistad’ with rich purple flowers on near-black stems. For compact shrubs in small spaces, Salvia microphylla ‘Hot Lips’ gives playful red and white blooms that deepen in cooler weather.
For damp sunny spots, Salvia uliginosa sends up airy sky-blue spires that mingle beautifully with grasses. Give them sun and free-draining soil. Water new plantings, then mulch lightly.
In containers, water in warm spells and feed with a high-potash fertiliser through early September, then ease off to help plants harden. Stake tall types in windy sites and deadhead to keep flowers coming.
Ensure good airflow and water at the base. Salvias dislike heavy, waterlogged ground. In pots, watch for vine weevil and refresh tired compost. If an early chill blackens soft tips, trim them away. Most shrubby salvias are cut back in spring, so leave top growth over winter to protect crowns. In colder gardens, protect borderline-hardy varieties such as ‘Amistad’ with a thick mulch, or overwinter a backup cutting under cover. You can also take semi-ripe cuttings in early September for plants next year.
Fun fact: Salvia is from the Latin ‘salvere’ ‘to heal’, reflecting sage’s history as a medicinal herb.
Did You Know?
Fig trees and fig wasps rely on each other. Most fig species pair with a specific wasp that pollinates inside the fig while the wasp completes its life cycle there, so both partners benefit from the relationship.
In Ancient Egypt, onions were revered as symbols of eternity. Their concentric rings and long-keeping qualities made them powerful emblems, so they featured in offerings and burials as a sign of everlasting life.
Frogs don’t drink like humans do. Instead, they absorb water through a specialised patch of skin on the belly and thighs, so staying on damp surfaces helps them hydrate without taking water into the mouth.
Rain’s earthy aroma is called petrichor. When raindrops strike dry ground, tiny bubbles fling plant oils and a bacterial compound called geosmin into the air, creating the familiar scent that signals a change in the weather.