With back to school comes back to work in the garden, as you set to repair broken lawn edges, replace summer bedding and cover late salad crops with fleece as the cooler weather threatens.

[Read more: Top tips to give your vegetable patch a head start for the autumn]

And there’s still plenty of harvesting to be done. Here's some jobs to put on your to-do list for September.

Give your flowers some TLC

- If you need some new border perennials to fill gaps or replace lost specimens, many are suitable to plant in the autumn as the rainfall in the cooler months should keep plants healthy. Fork over the planting areas, adding in some well-rotted organic matter.

Choose days for planting when the soil is moist and the weather not too cold. Water the plants in and continue to keep them moist until they are well established

-Transplant summer-sown biennials into gaps left by the summer bedding that you’ve cleared.

- Plant spring-flowering bulbs including daffodils and fritillaria to give early colour and pot-grown wallflowers to compliment them.

- Take cuttings of regal pelargoniums in case you lose the main plants over winter. They should root in four to five weeks on a heated bench or open propagator. Never cover them with a lid as this will increase humidity and make them rot. Never let the compost dry out at the roots.

- Visit local dahlia shows and gardens to identify new varieties you want to grow.

Think about container displays

- Plant up winter containers now, so they can establish themselves before the really bad weather sets in. Try cyclamen, winter-flowering heathers and pansies for colour, as well as container-grown shrubs including small-leafed hebes and skimmia, while ornamental cabbages bring form and colour to winter pots.

- Don’t forget to plant spring bulbs in window boxes and containers. Zingy yellow dwarf narcissi, deep blue muscari and other dwarf bulbs including scillas, chionodoxas and early crocuses are perfect for pots.

[Read more: 12 of the best plant pairings to keep pests away from your vegetable patch]

Pep up your lawn

- Now’s the time to pep up your lawn. When the wet weather comes, scarify and spike your lawn to remove moss and dead grass, improve oxygenation and relieve compaction.

- Give the lawn an autumn feed and add top dressing, especially if you have clay, chalk or sandy soil

Don't forget your vegetable patch

- Continue to harvest courgettes, sweetcorn, French and runner beans, lettuce, autumn cauliflower, pencil leeks and the last of the globe artichokes.

- At the end of the month, cover late crops of salads, carrots and courgettes with horticultural fleece or cloches to protect them during the cold nights.

- Sow overwintering onions in vacant rows on the veg patch, thinning them out in October.

- Early-maturing dessert and cooking apples for storing may be ready for picking in the second half of the month. Store large crops by wrapping them individually in newspaper and packing them in boxes.

- Pick early dessert pears when still hard and ripen them indoors. If you are storing them, pears should not be wrapped, but stood on trays or shelves.

- Pick plums and cherries as they become ripe but beware of wasps when picking.

- Prune summer-fruiting raspberries, cutting down the stems that have fruited this year to just above the ground. Tie in the new canes that have grown this year, which will carry next year’s fruit.

In the greenhouse...

- Gradually reduce feeding and watering of all greenhouse plants as their growth slows and flowering stops.

- Bring in tender plants from their outside summer quarters, pick off any damaged leaves and remove the top layer of compost, replacing it with fresh.

- If you want spring colour under glass, plant some spring bulbs in an unheated greenhouse, to flower several weeks earlier than bulbs outdoors.

- Remove the growing tips of indoor jasmine (Jasminum polyanthum) and keep the plants in a bright position as the flower buds form. Water well and continue to feed every two weeks.

Tidy up

- As marginal pond plants begin to fade, remove old flower heads from them and cut back the top growth of plants that will die back naturally anyway, before they collapse and decay in the water.

- Erect a net over your pond or water feature if it is near deciduous trees, to stop leaves from falling into the water and decomposing.

- As you empty your finished summer bedding, give your pots a really good clean to stop pests overwintering in them and if you are not going to replant containers with winter displays, put the pots away in a shed.

- Get ahead by cleaning the greenhouse if your summer crops such as tomatoes have already come to an end. Prepare greenhouse border soil and sow winter salads.

- Clip hornbeam, beech Leylandii and thuja hedges before the middle of the month or you may not be able to keep on top of them.