Here are your September gardening jobs with links if I have more information on the subject. Some of August’s jobs are relevant to do now if you’ve fallen behind or if the weather’s been bad.
Week 1
Summer prune apple and pear trees to encourage more fruiting spurs. Put grease bands on fruit trees to catch wingless winter moths.
Keep picking autumn-fruiting raspberries and pruning out fruited canes on summer-cropping varieties.
Plant out rooted strawberry runners and pot some up to bring into the greenhouse later in winter for early fruits.
Vegetables to sow now include lettuces, spinach, land cress, purslane, beetroot, radishes, coriander, spring onions, calabrese, spring greens, turnips for their green tops, Swiss chard, winter spinach and hardy Japanese onions.
Sow hardy annuals to provide early spring blooms – pull up hardy annual plants if you don’t want them to set seed everywhere.
Harvest cucumbers regularly to promote further flower development.
Stop watering begonias and Gloxinia so they die down after flowering.
Start watering dormant cyclamen to bring them back into growth after their summer rest.
Catch earwigs in upturned pots crammed with newspaper or straw on canes among dahlias and destroy any you find.
Prune Pyracantha and train shoots to supports.
One of the most important September gardening jobs is planning for the future. Prepare the soil to plant evergreen shrubs and conifers by digging it over and incorporating lots of organic matter.
Prune lavender to maintain its shape, and take lavender cuttings by pulling off side shoots and inserting them in trays of gritty compost.
Prune rambling roses, removing shoots that have finished flowering.
Plant conifers, shrubs and hedging.
Buy spring-flowering bulbs like tulips, crocuses, narcissus and fritillaries.
Trim box topiary and hedging.
Hoe and hand weed borders.
Remove suckers from roses, shrubs and around the base of trees.
Pinch out the tips of wallflowers to promote bushier growth.
September gardening jobs – Week 2
Sow hardy annuals (Consolida, Calendula, Centaurea, Limnanthes, and poppies) where they are to flower next year.
If you sowed spring-flowering biennials such as Viola, Digitalis (foxglove) or Erysimum (wallflowers), earlier in the summer, they will now need planting out – nip out the tips to encourage bushy plants.
Deadhead annuals to keep them going until mid-autumn.
Inspect chrysanthemums for signs of white rust.
Plant up containers with Hippeastrum (amaryllis) bulbs and prepared hyacinths for a Christmas display.
Order mature or large plants now for planting next month or once the rains have moistened the soil.
Harvest apples, pears, plums and gages.
Now is an ideal time to apply biological controls for use on vine weevil grubs. Target fuchsias, succulents and container plants.
Pot up herbs, such as tarragon, to use in winter.
Plant out garlic, or start cloves in pots to transplant later.
Prune out fruited blackberry/tayberry/loganberry stems and tie in new shoots to supports.
Vegetables to sow now include spring cabbages, Japanese onions, turnips for green tops, winter lettuces, spinach, endive, corn salad, land cress and baby salad leaves.
Week 3
Continue to deadhead plants such as dahlias, delphiniums, roses and Penstemon to prolong the display.
Divide any overgrown or tired-looking clumps of alpines and herbaceous perennials, such as Crocosmia. This will invigorate them, and improve flowering and overall shape for next year.
Continue picking sweetcorn, beans and marrows.
Take cuttings of tender perennials, such as Pelargoniums (geraniums). If you don’t have a greenhouse, use a light windowsill to grow them on.
Bring inside tender perennials, such as Fuchsia, Gazania, Lantana and Abutilon.
Some tall-flowering perennials, such as asters, may still need staking to stop them being blown over in the wind.
Prune late-summer flowering shrubs such as Helianthemum (rock rose) and give evergreen hedges a final trim to make sure they are in shape for winter.
Start to reduce watering of house plants as light levels drop.
Ventilate conservatories during warmer days but close windows at night.
Top up pond water levels when necessary and continue to remove blanket and duckweed. You may need to thin out submerged oxygenating plants, as they can quickly build up and crowd the pond.
Make and repair compost bins so that they are ready for the autumn when fallen leaves will quickly fill them.
Pick ripe apples and store the best in fruit crates.
Dig up strawberry runners and pot them up.
Net autumn raspberries and blackberries to protect them from birds.
Lift and dry maincrop potatoes and store in paper sacks in a cool, dark place.
Sow broad beans and hardy peas for early crops next year.
Vegetables to sow now include winter radishes, lettuce and salad leaves, spinach, spring onions, and turnip for its green tops.
Check pears regularly to harvest when perfectly ripe.
September gardening jobs – Week 4
This is a good time to plant new perennials, as the soil is still warm, but moisture levels are increasing.
Wait for the first frosts to hit dahlias and cannas before lifting the tubers or rhizomes. In warmer regions, they may be OK left in the ground, but cover the crowns with a protective layer of straw or bracken.
If the weather is already autumnal, you can plant and move shrubs and trees.
Climbing roses can be pruned once they have finished flowering; side shoots from the main branches can be cut back to a couple of buds. Cut out dead, diseased, or spindly growth and tie new young shoots tied into supports, from the base. Remove old, thick, woody and unproductive stems.
Clear dead leaves once they start to fall, as they can be a source of disease. They can be shredded to help them break down quickly on the compost heap. It is one of the most vital September gardening jobs to throw out or destroy affected leaves.
When bringing plants indoors, check for pests and diseases, in particular, red spider mite, mealybug, and scale insect. Inspect rootballs and compost for vine weevil larvae and treat where necessary.
Cover the surface of ponds with netting to keep out fallen leaves. Debris can encourage the growth of algae and weeds, which will harm fish by reducing oxygen levels. Remove dead leaves from water lilies. Divide water lilies and other pond plants to increase stocks. Overgrown marginal plants can be cut back. A maximum of 50 per cent of the water’s surface should be taken up with planting.
Vegetables to sow now include winter radishes, lettuce and salad leaves, spinach, spring onions, and turnip for its green tops.
One of the important September gardening jobs is cleaning the greenhouse before bringing in all your tender plants. Pests and diseases can hide in tiny nooks and crannies. Hose down the structure and use safe cleaning products such as Citrox, and a non-abrasive scourer recommended for cleaning glass.
Prune out fruited blackberry stems and tie in new ones.
Sow sweet peas in a cold greenhouse for early summer blooms next year.
Sow turnips for spring greens in March and April.
Clear crops once they’ve finished and fork over beds. Cover with spiny branches to deter cats.
For October gardening tasks, see my week-by-week tasks page.
