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
Aromatic, summer flower spikes and a bushy habit combine to make this evergreen shrub a must-have. Happy in most types of well-drained soil, use in borders, pots, or as edging. One order per customer (i.e maximum four pots).
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'Easy Wave Ultimate Mixed' is a blend of over 15 types of petunia flowers. Ideal for filling containers, hanging baskets and window boxes, they bloom from June to October in a range of cheering shades.
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Shortlisted for the RHS Chelsea Plant of the Year 2019, this unique clematis bears flamboyant, ruffled, double, rich purple blooms against lush green foliage from June to October.
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