Nights are drawing in, there is condensation on the windows and blackberries are dripping off brambles – this month every good day needs to be treasured. I see September as the beginning of the gardening year preparing for next season by taking cuttings, collecting seed, making plans and ordering bulbs.
This is the month to take semi-ripe cuttings – shrubs and herbs mostly tick the box. By definition a semi-ripe cutting is a stem of this year’s growth which has started to harden off at the base a bit but is still being bendy at the top. This year I have been collecting Hebe, Box, Yew, Artemisa, Rosemary, Lavender, Purple Sage and Osmanthus amongst others.
By taking a cutting you are essentially creating a clone of the mother plant so if there is one in your garden that you particularly covet and want more of, this is the way to do it.
It is also a great time of year to take cuttings of any tender perennials you might have – such as Salvias and Pelargoniums, whilst they are still in full growth mode. The trick is to bring them inside before the frosts and to keep them almost bone dry over Winter – only start watering in the Spring when new growth starts to appear. Take small cuttings, cutting just below a leaf node and removing most of the leaves, plant in a gritty compost mix, do not cover them and put on a windowsill – they should root in about 3 weeks at this time of year.
Many veg will keep going till the first frosts – they may need a little feed now and then and keep an eye on mildew. Now is also a great time to give your herbs a trim and perhaps pot some up to bring inside. Tomatoes are at their best right now – treat them mean by giving them very little water and feed as this will mature the fruits. And harvest those apples as soon as you can hold and twist them off the trees.
Plant out any biennials you have been growing over the Summer – things like Foxgloves, Wallflowers, Lunaria and Hesperis will all be good sized plants by the middle of September. Planting them out now while the earth is still warm will mean they can really get their roots down and come Spring you should have strong healthy plants to fill the gaps before the other perennials really get going.
September is a good time to prune yew hedging or topiary. All fledglings have flown the nest and, clipped now, the hedge will retain its architectural sharpness of outline right through the next nine or ten months. Work from the bottom up so that the trimmings fall away and you can see where you are going and make the hedge wider at the base and narrower at the top. This way it will stand up to the weather better and ensures that light reaches the base of the plant as well as the top which will encourage the best growth.
Dividing Herbaceous Perennials
Left to their own devices, perennials can form oversized clumps which lose vigour and die out in the centre, leaving gaps in your planting. Now is a really good time to divide clumps to keep them healthy and to add to your plant collection! Almost all perennials will thrive following autumn division, particularly species that flower earlier, such as Brunnera macrophylla, Saxifraga, Pulmonaria and hardy geraniums. The ground is still quite warm and moist, dig a spade in and lift the rootball of the plant from the soil. Separate the clump into small pieces making sure each has roots and leaf and replant as quickly as possible into moist soil.
Collecting seed from your own plants is hugely satisfying and everyone should give it a go! Seeds must be collected on a dry sunny day and when the seedheads themselves have not a trace of moisture. Have a look out for Lunaria, Verbascum, Silene, Ammi majus, poppies, and put stalks head first into a paper bag, storing them somewhere cool and dry, until you want to sow them.
A number of hardy annuals can be direct sown, but I am useless at telling the difference between a weed and baby seedling and so always sow in seed trays/9cm pots so I can have some sort of vague control! Once sown, germinated, and pricked out, plants can sit in a cold frame, be watered once every three days and have no need for any heat – in fact they don’t need much looking after all.
Catalogues fly through the letter box at this time of year and the first order always includes Hyacinth bulbs which really need to be planted up by mid September latest, if you are to have blooms for Christmas. You will need to make sure they are ‘prepared bulbs’ which simply means they have been chilled over the summer. Layer a bulb bowl or planter with compost or bulb fibre, bed in your bulbs, close but not touching, and then cover with more compost so the top of the bulbs are still showing. Place them in a dark cool shed (or with a bin liner over them) and water when drying out. When the shoots are 4/5cm long, bring the bulbs inside to a light cool spot inside to develop further. When really established bring them into the warm to flower on Christmas Day!
Tulips can wait till next month! There’s always something else to look forward to with this gardening obsession!