What to do during September in your garden and greenhouse.
Your monthly gardening checklists
Flowers
- Sow hardy annuals, such as cerinthes, ammi, scabiosa and cornflowers, for flowers early next summer
- Lift gladioli corms, dry them off, then store in a frost-free shed or garage over winter
- Plant wallflowers, pansies, forget-me-nots and other spring bedding in pots and borders
- Collect ripe seeds from your favourite flowers and store in labelled envelopes, ready to sow in spring
- Plant up containers for autumn interest, using cyclamen, heathers, heucheras and other colourful bedding plants
- Bring any houseplants that you moved outside over summer back indoors, before temperatures start to drop
- Lift, divide and replant congested clumps of perennials, such as achilleas, once they finish flowering
- Apply vine weevil control to pots if plants show the tell-tale sign of notched leaf margins
- Fill any gaps with late-flowering perennials, such as sedums, to provide nectar for pollinating insects into autumn
- Plant spring bulbs, including crocuses, daffodils, hyacinths, bluebells and snake's-head fritillaries in pots and borders
- Take cuttings from fuchsias, salvias and pelargoniums
- Keep summer bedding flowering in hanging baskets and pots until the first frosts by deadheading and feeding regularly
- Trim conifer hedges to neaten them up and control height
- Leave sunflower seedheads in place for birds to feed on
On the forum: share your growing tips with other gardeners and ask for advice
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Fruit and veg
- Sow hardy greens, such as kale, land cress, pak choi, mizuna, lamb's lettuce and mustard, for winter pickings
- Prune out all the fruited canes of summer raspberries, cutting down to the base, and tie in new canes to supports
- Pot up herbs, such as chives and parsley, and place on a sunny windowsill to use during winter
- Start sowing hardy varieties of broad beans and peas for early crops next year
- Plant onion and shallot sets in a sunny spot, 10cm apart, with the tip just showing above the soil
- Cut away any leaves covering the fruits of pumpkins, squash and marrows to help the skins ripen in the sun
- Plant saffron crocus bulbs (Crocus sativus), so you can harvest your own saffron this autumn
- Pick apples and pears before the wind blows them down, and store undamaged fruits if you can't eat them fresh
- Store chillies by threading the stalks onto strong cotton or wire and hanging up to dry somewhere warm and dry
- Cut off trusses of unripe outdoor tomatoes before the weather turns cold, then ripen them indoors
- Lift maincrop potatoes, dry off and store in hessian or paper sacks, in a cool, dark, well-ventilated place
- Complete summer pruning of both free-standing and trained apple trees, to encourage good fruiting in future years
On the forum: which fruit and veg varieties are you growing?
Summer prune apple and pear trees
Greenhouse
- Plant prepared hyacinth bulbs in pots or hyacinth glasses, for fragrant indoor flowers at Christmas
- Take down greenhouse shade netting or wash off shading paint by the end of the month, as light levels start to fall
- Stay vigilant for pests and diseases in the greenhouse, and treat any you find immediately
- Plant dwarf spring bulbs in pots, including irises, crocuses, chionodoxa and scilla, for early flowers
- Pot up tender perennials, such as fuchsias and osteospermum, from summer displays and bring indoors before temperatures drop
- Repot moth orchids after flowering if they look like they're about to burst out of their pot
- Water houseplants less frequently and move them off particularly cold windowsills at night
- Plant hippeastrum (amaryllis) bulbs in pots for spectacular flowers over the festive season
- Plant Anemone De Caen corms for a vibrant indoor display in early spring
- Pay close attention to greenhouse ventilation, shutting vents on cool nights
- Check greenhouse heaters are in good working order
- Maintain good plant hygiene, picking off faded blooms and dead leaves before fungal diseases can take hold
- Look out for forecasts of early frosts and be ready to bring tender potted plants under cover
- Move potted peaches and nectarines into a cool greenhouse or porch
Pot up Hyacinths for fragrant indoor flowers.
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Garden maintenance
- Rake thatch from lawns, aerate well-trodden areas by spiking with a garden fork, and re-seed bare patches
- Put netting across ponds to stop autumn leaves falling in and rotting
- Water autumn-flowering asters regularly to deter mildew
- Clean out water butts and check downpipe fittings in preparation for autumn rains
- Remove duckweed, pondweed and algae from water features and ponds
- Check that tree ties and plant supports are firmly in place, ahead of any autumn gales
- Wash and disinfect bird feeders and tables to maintain hygiene
- Collect fallen leaves to store in a chicken-wire cage or bin bags to make leafmould
- Hunt for rosemary beetles on lavender and rosemary, picking off the striped metallic beetles and their grey larvae
- Collect up and bin apples, plums and pears infected with brown rot, to reduce the spread of this fungal disease
- Order bare-root fruit trees to plant later in autumn or winter
- Check roses for signs of fungal diseases, such as blackspot, and pick off and bin all affected leaves
On the forum: join in the discussion, share your wisdom and ask for help
Pick off and destroy any leaves with blackspot
This long-flowering patio sunflower came in third place in the 2018 RHS Chelsea Flower Show Plant of the Year competition. This showstopper will add colour to your garden throughout summer and autumn.
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This hardy perennial bears sweet-scented small white flowers from April to July. This pretty plant is ideal for ground cover in shady garden areas. Buy three 1L pots for just £14.99.
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Robust, mildew-resistant variety flowering, in an array of bright colours, from June to November. These plants will quickly spread filling pots and borders - and are happy situated in sun or semi-shade.
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