Make the most of the late summer in September; continue with dead heading and weeding to extend the flowering season and keep soil nutrients and moisture for your plants and not the weeds.
Sowing and planting:
Bulbs make fine displays planted in containers or borders, especially daffodils, snowdrops and tulips in springtime. They are one of the easiest and most rewarding garden plants to grow. Most spring-flowering bulbs should be planted by the end of September with the exception of tulips which should be left until November. Look out for new varieties as well as much loved old favourites. When planting daffodils in containers its worth planting two layers of bulbs, slightly staggered one above the other. This will ensure a spectacular display. Plant the bulbs deeply enough to allow you to plant winter and spring bedding, such as winter pansies, primroses, violas and wallflowers on top.
Sweet pea lovers may find that sowing seed in autumn produces stronger plants. Do not soak the seeds as they are liable to rot. Use Seed and Potting Compost and sow the seeds in root trainers, sweet peas tubes, pots or trays. Cover the containers with glass or put them in a propagator and keep at around 15 C (59 F). When the seedlings appear transfer them to a cold frame. Pinch out the growing tips when the plants are about 10 cm (4 inches) high.
Once summer bedding has gone over, plant up containers/baskets/fill gaps with autumn and winter bedding such as winter pansies, Violas, Cyclamen, Wallflowers and Sweet Williams.
Now’s the time to go around your garden collecting seeds from perennials and annuals. Collect seed heads in paper bags and leave them in a warm place to dry for a few days before cleaning and storing in small envelopes. Some gardens that are open to the public offer seed collecting days – a great way to find something unusual!
Shrub roses and ramblers can easily be propagated from stem cuttings at this time of year. Take a length of stem about 30cm (12 inches) long and trim it off just below the bottom leaf. Remove the soft tip. Take off all but the top two or three leaves and push the cuttings into a well dug trench in the garden to about half their length. They should be left for twelve months to root and develop.
Continue to take cuttings of tender perennials and divide herbaceous perennials.
Prune late-summer flowering shrubs and give evergreen hedges a final trim.
Prune climbing roses once they have finished flowering, removing any dead, diseased or spindly growth. Cut side shoots from the main branches to a couple of buds. Tie in new young side shoots to supports. Any old, thick and woody unproductive stems can be removed from the base to stimulate more vigorous growth.
In the greenhouse:
Damping down usually becomes unnecessary as the month progresses. It is best to do any watering early during the day so that the greenhouse is dry before evening. Dampness during cool nights could cause Botrytis (a fluffy grey mould) and damping off of seedlings (a disease of seedlings caused by several different fungi and fungus-like organisms which causes seedlings to collapse.)
Ventilate during warmer days, but reduce ventilation once the cooler weather arrives.
Reduce shading towards the end of the month as light levels fall.
Raise the height of cut as as the growth rate of the grass slows down, mowing less frequently during autumn.
Apply an autumn lawn feed which is high in potassium after scarifying and aerating. Do not give summer feeds that are high in nitrogen as this will only result in weak, soft growth, which will be prone to disease in the autumn weather.
This month is the last chance to use lawn weedkillers to control perennial weeds such as daisies and buttercups.
This is an ideal time of the year to create new lawns or repair patches with seed or turf.
In the south of England you can still sow quick maturing salad crops such as summer lettuce, radish, rocket, sorrel, chicory and fennel. If you’re sowing out of doors this month you can speed up germination by putting a cloche over the seeds.
Continue to sow spring cabbage, turnips, Oriental vegetables and overwintering onions.
Sow green manures such as crimson clover and Italian ryegrass to act as a soil improver and to cover bare areas. When dug in, they conserve nutrients and improve soil texture.
Pick autumn raspberries.
Dig up remaining potatoes before slug damage spoils them.
Ensure all vegetables are watered well during dry spells. A consistent supply of water will aid healthy development and help to avoid diseases, disorders and bolting.
Prune soft and bush fruit such as plums, gauges and damsons immediately after harvest.
Cover autumn-fruiting blackberries and raspberries with netting to keep off the birds, but check daily to ensure no animals or birds get trapped.
Good hanging basket/planted container maintenance can keep displays going until mid-autumn. Continue deadheading, watering and feeding. When they are past their best, re-plant using winter bedding (click here for details) and spring flowering bulbs (click here for details).
Deadhead plants such as dahlias, roses, penstemons and delphiniums to prolong displays.
Cut back perennials that are fading and dying down.
Plant or move trees/shrubs as the autumn weather arrives. This is the ideal time as they will have the winter to settle in before new growth starts in spring.
Clear dead leaves promptly once they start to fall, as rotting leaves can be a source of disease in the garden. They are, however, useful on the compost heap and can be shredded first with a shredder or mulching mower to help them break down quicker.