Essential tasks for September Keep your garden looking its best with our guide to essential jobs that need doing in September.

In this article

Flower garden Greenhouse

Kitchen garden General care

Add plants for autumn interest

Create a striking feature in your borders by using some plants that look good during the autumn months. One of the best plants to choose is Sedum spectabile 'Brilliant' which produces masses of flat, bright pink flower-heads on upright stems with succulent, glaucous leaves. Grow sedums in full sun in a well-drained soil and divide every few years to improve flowering. Other plants which are also good at this time of year include ornamental grasses, heleniums and perennial asters, Michaelmas daisies.

Plan for spring

Plant up patio pots or borders with erysimum, more commonly known as wallflowers, for a cheery spring show. Although they can be grown on their own, try planting tall-growing tulip bulbs in a contrasting colour first and planting the wallflowers over the top. The tulips will then grow up through them to provide an extra layer of height and colour.

Deadheading

Deadhead roses as the blooms fade, cutting off the flowers just above the uppermost leaf on the stem. Trim back lavender bushes after flowering to remove the old blooms and shoot tips, taking care not to cut back too heavily into any old wood. Removing faded flowers from perennials and annual plants will also ensure a continued display of blooms.

Attend to bedding

Give bedding displays, hanging baskets and pots a little attention to ensure their display lasts well into autumn. Pick over plants twice a week to remove any faded blooms, keep watering daily and control pests when you find them. Any tender plants you want to save for next year can also be potted this month, so they are established and ready to bring under cover when the weather turns cooler.

Support perennials

Put plant supports around tall, late-flowering perennials to prevent them from being damaged by autumn winds. Create your own plant support with our step-by-step guide to making a willow obelisk.

Greenfly checks

Look out for greenfly on winter-flowering pansies and other plants. Treat with a suitable insecticide.

Deadhead roses

Give roses a final deadheading when the blooms have faded and shorten tall stems slightly to reduce wind rock. However, leave those that have developed hips for some extra autumn colour.

Hardwood stem cuttings

Take stem cuttings of roses in early September by pushing cut stems straight into the soil in a nursery area of the garden, where they can be left to root and develop for about a year. Most types of rose can be propagated from cuttings, especially the rambling types. Just take a length of stem, removing the soft tip above a leaf joint, and cut below a joint at the base, removing all but the top three leaves. Then push the 30cm (12in) cutting into the soil to about half its length.

Lilies

Buy lily bulbs as soon as you find them for sale and plant them straight away. Propagate Asiatic lilies, such as Lilium 'Angela North', L. 'Ariadne' and L. 'Enchantment' by picking the small bulbils from their leaf joints and growing them on. Plant them in trays of compost and leave them to develop into new plants.

Gladioli

Enjoy gladioli spikes in the garden or cut them for displays in the house. Spray plants with a suitable insecticide if thrips start to be a nuisance. When flowering is over, the corms can be lifted, cleaned, labelled and stored carefully for planting out again next spring.

Dahlias

Give large dahlias an extra feed during August to promote strong, healthy growth. Regularly tie them to their supports to prevent the stems from breaking in the wind, deadhead garden displays and cut blooms to enjoy in the house.

Cuttings

Finish taking cuttings of fuchsia, heliotrope, verbena, coleus, argyranthemum and other tender plants, which can be overwintered on frost-free windowsills. Discover the best way to propagate tender plants with our guide to taking pelargonium cuttings.

Bulbs

Look out for indoor bulbs such as lachenalia and veltheimia, for autumn planting and daffodils that are prepared for early flowering at Christmas, such as Narcissus 'Fortune', N. 'Cragford', N.'Golden Harvest'. Start watering dormant cyclamen pot plants which have been left to die down for a rest. Freesia corms can also be planted in pots now for early, fragrant blooms next spring.

Harvesting crops

Regularly pick crops so that they are always tender and fresh. Never leave crops for too long before picking them, especially beans and courgettes.

Crops to sow

From August to early September the following crops can be sown directly outside:

• lettuce and salad leaves
• Chinese cabbage
• endive
• winter spinach
• turnips for their green tops
• final sowing of spring cabbage

A cloche cover can help speed up germination in colder areas.

Outdoor tomatoes

Pinch out the shoot-tips of cordon tomatoes grown outdoors once their third or fourth truss has set fruit.

Protect late crops of soft fruit

Cover autumn-fruiting raspberries, blackberries and other cane fruits with netting to keep the birds away. Do remember to check the netting daily to ensure that no birds or animals are trapped.

Apples

Keep an eye on early ripening varieties, such as 'Discovery' and pick the fruit as soon as it's sweet enough to eat. Most early varieties won't keep, so eat them while they are at their best. Hang wasp traps in the branches of fruit trees to prevent wasps from damaging fruit.

Peaches

Prune away all shoots that have carried fruit and tie in new ones that have formed this year. These will flower next spring.

Blackberries

Bury the tips of any shoots that have developed this year into the soil to raise new plants. These tips will quickly form roots and shoots will develop next spring, when the new plants can then be separated and planted elsewhere.

Sweet corn

When the golden silks of sweet corn have turned brown they should be ready to harvest. Peel back the husks to check that the cobs inside have swollen to their full size. Cook them within minutes of cutting them if you can, to ensure the sweetest flavour.

Herbs

Pick herb stems for drying, or chop them up and keep them in ice cube trays in the freezer.

Onions

Carefully lift ripe onions, breaking the roots and lay them out to dry before taking them into store.

Trench celery

Wrap several layers of newspaper or cardboard around individual celery plants, then pull up the soil around them. Excluding the light in this way helps produce clean, blanched stems.

Trim hedges

Make sure your plants are well shaded on hot days to prevent scorch. The easiest way to do this is to apply netting or shade paint to the outside of the glass. Scorch is exacerbated if leaves are wet, so take care when watering plants. Use our guide for further tips on pruning hedges.

Lawn care

Prepare areas of ground for sowing new lawns later in the month.

Collect seeds

Make the most of free seeds produced by perennials and other garden plants by saving them when they are fully ripe. Collect mature seed-heads in paper bags and hang them in a warm place to dry out. The seeds can be cleaned and sorted, then put into labelled envelopes and stored in a cool, dry place. Swap your seeds with your friends to share in each other's successes.