September Gardening Tips
For most, September signifies the end of summer, with its generally cooler weather and shorter days. While there’s not as much to do in the ornamental garden, if you have a fruit or vegetable patch, you’ll be busy harvesting!
FLOWERS AND PLANTS
Continue deadheading and weeding.
Deadhead all your tender perennials. This will give them a new spurt of life.
Prune climbing/rambling roses once they’ve finished flowering. Remove suckers from the base of roses and trees. Remove any fallen leaves from the base of roses to prevent the spread of disease.
Later in the month plant spring bedding such as wallflowers, primulas and violas for a colourful spring display.
Start planting new perennials as well as trees/shrubs/climbers.
Order mature or large plants now for planting in October or once the rains have moistened the soil.
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.
Prune late-summer flowering shrubs and give evergreen hedges a final trim to make sure they are in shape for winter.
IN THE VEGETABLE GARDEN
Bean and pea plants that have finished their harvest can be cut back, leaving the roots to be dug in to the soil to provide extra nitrogen for future crops.
Sow spring onions – these will be ready to eat before the frosts get going in most parts of the country. Even if frosts are forecast, they are fine under glass or plastic to harvest through late winter and autumn.
Remove any crops that have finished leaving unneeded areas clear – weeding and tidying for the winter. Keep an eye on your brassicas for butterfly eggs and caterpillars; these will most probably be under the leaves.
Sow Swiss chard, winter spinach, broad beans and hardy peas.
Keep watering winter squash and pumpkins if the weather is hot. Use stored rainwater wherever possible.
Prepare a bed for autumn-planted shallots. Incorporate well-rotted compost into the area to improve fertility. If your ground is wet, a raised bed may be a better option. Plant the sets from the end of the month, with the tip just protruding from the soil.
Do a last outside sowing of radish. With the soil still warm and moist with dew, you should be eating these in four to five weeks.
Sow all your autumn-winter picking salad leaves and herbs if not done in August.
Cut and hang herbs to dry for using in the kitchen over winter.
If weather is dry, water well. Pot up less hardy herbs such as parsley, chives and French tarragon and bring inside into a sunny, frost free spot.
IN THE GREENHOUSE
When bringing plants inside, check carefully for any pests and diseases they may have picked up outside, in particular red spider mite, mealy bug and scale insect. Inspect root balls and compost for vine weevil larvae and treat where necessary.
Clean out your greenhouse to reduce the risk of pests and diseases overwintering.
If temperatures drop, close doors and vents over night to keep it as warm as possible.
Towards the end of the month as the light levels fall, remove shade netting from greenhouses or wash off shade paint.
Water plants sparingly, but damp down the greenhouse by watering the floor each morning. The humidity will mean you have to water less often.
IN THE FRUIT GARDEN
Once harvested, it’s time to start thinking about pruning back your fruit trees and shrubs to maximise yields next year. The sooner this is done after harvesting the better.
Pot strawberry runners to make new plants for next summer.
Cut back the fruited canes of summer raspberries, tying in the new green canes for next year’s crop.