This is the month of Michaelmas daisies, the asters. September is also the month when the early flowering chrysanthemums and dahlias should look their best and when the large herbaceous sedums and tall rudbeckias should be in full flower. Borders should still be fed and watered occasionally, but some plants will have now passed their best and it’s a good time to lift and divide them. The summer bedding plants should still be in full flower, but we have to watch out for early frosts which may arrive this month, and to prolong the summer display it’s a good idea to cover up with fleece when the weather man gives us the warning. We can start to plant the winter pansies, Canterbury bells, forget-me-nots (myosotis) and primroses now. Certainly the winter hanging baskets should be started and there should be a good selection of suitable plants in the garden centre to choose from. Bulbs such as daffodils, tulips, hyacinths, crocus and a host of dwarf types are now on sale and should be purchased as soon as possible while there is such a good selection. Paperwhite daffodils and the like should be planted in bowls in bulb fibre for flowering indoors during the winter. For Christmas flowering, prepared hyacinths should be planted as soon as possible in bowls and kept in the dark for a month or so, but there is no hurry to plant outdoor bulbs just yet.
Potatoes, carrots and onions should be lifted by the end of the month and marrows and courgettes will need to be harvested before the frosts start. Garlic bulbs and the early onion sets can soon be planted and spring cabbage plants should be set out. Sow winter lettuce and late radishes as well. If the soil is heavy, September is not too early for starting the digging. Apples and pears should be harvested and greasebands should be put on the trunks of fruit trees. Lawns will still need to be mowed occasionally and it’s a good idea to scarify and aerate them now prior to applying an autumn feed. If there is a moss problem, use lawn sand instead of autumn feed, and if there are problem weeds on lawns, Verdone can be effective. Big problem weeds in the garden can be controlled by spraying with Glyphosate. With autumn approaching, now is the time to cover ponds with netting to prevent leaves getting in and to clear up garden rubbish before the weather deteriorates. September is a good time to start planting container-grown trees and shrubs, to take hardwood cuttings and to start taking cuttings of fuchsias and geraniums under glass. This is also the best month to sow sweet peas in the greenhouse so that they will be ready for planting out in the spring.
The gardens at Knebworth House are open on Wednesday 1 September and at Waddesdon Manor on Wednesday 22 September. Campden Cottage gardens at Chesham Bois are open on Sunday 12 September. The National Amateur Gardening Show is at Shepton Mallett on 3, 4 and 5 September and the Malvern Autumn Show is on 25 and 26 September. There is a Garden Show at Hatfield House on 3, 4 and 5 September and Chipperfield has its own Flower Show on 18 September.
Terry Simmonds