The cold, hard truth is that winter is not too far off in the garden

You can’t afford to bury your head in the soft ground of autumn. Prepare for November.

If you sowed seed of hardy flowering biennials such as foxgloves, Canterbury bells, wallflowers and honesty earlier in the summer, move these young transplants into their permanent growing positions as soon as possible.  Picture: iStock

Like a lot of people, I try my best at this time of year to ignore the fact that autumn has arrived while winter is fast approaching. 

But of course, this head-in-the-sand approach only ever works for so long. Instead, everywhere in the garden are unmistakable signs of the seasonal shift, from trees heavy with fruit and spiderwebs silver-beaded with dew, to shades of gold and nutmeg in the hedgerows. Much as we might wish summer to linger a little longer, the year is inexorably turning, a signal to us gardeners that it’s time to take stock as well as to plan ahead.

Any recently emptied vegetable and cut-flower beds, for example, should be covered with a thick organic mulch of well-rotted manure, responsibly foraged seaweed or home-made garden compost to prevent weedy growth from quickly colonising all that bare ground, bearing in mind that nature abhors a vacuum.

Or if that seems like too arduous, time-consuming or expensive a chore, then the alternative – a good one – is to sow a green manure such as winter vetch, grazing rye, white mustard or winter field beans to nourish and protect the soil. Failing that, cover any emptied beds with a layer or two of brown cardboard or strong black plastic sheeting weighted down with stones, or with the edges neatly trenched into the ground.

Just make sure to strike while the iron is hot. Now that heavy rains have refreshed thirsty soils and the latter are still warm from repeated heatwaves, conditions are ideal for optimal germination and quick growth. But they’re less likely to be so in a month’s time.

Which is not to say that there aren’t any very useful overwintering food crops that can still be sown or planted over the coming weeks. For example, it’s well worth leaving some growing space uncovered to sow or transplant varieties of hardy winter salad leaves such as mizuna, mustard, pak choi, tatsoi, claytonia and corn salad (stockists include greenvegetableseeds.com and brownenvelopeseeds.com), as well as to plant spring cabbage (these as young transplants) and overwintering varieties of onions (these as sets). Hardy varieties of garlic and broad beans can also be sown or planted next month, all crops that will prove their worth next spring.

If you sowed seed of hardy flowering biennials such as foxgloves, Canterbury bells, wallflowers and honesty earlier in the summer, move these young transplants into their permanent growing positions as soon as possible so that they can establish decent root systems before growth slows.

That same window of opportunity will also soon close for sowing seed of decorative hardy annuals for flowering next summer. So grab the chance while you can to sow seed of orlaya, ammi, cornflowers, snapdragon, larkspur, Chinese forget-me-not, Argentine forget-me-not and marigolds for the reasons outlined above. Most of these will happily survive an average Irish winter outdoors without help, but in cooler parts of the country where harsh frosts are likely, they’ll benefit from either a protective layer of fleece or being overwintered in an unheated glasshouse.

At the risk of being shot for mentioning the C-word so outrageously early in the year, mid-September is also the cut-off point for planting Christmas hyacinth bulbs in time to force them into bloom for the festive season. Just make sure to use bulbs that have been specially treated for this purpose (try mrmiddleton.com).

Speaking of flowering bulbs, this is the time to start getting most kinds of spring-flowering bulbs in the ground or into pots, from narcissus, fritillaria, camassia and crocus to scilla, alliums and snowdrops. But hold off from planting tulips until late autumn or early winter to minimise the risk of disease.

To avoid accidentally introducing the latter into your garden, it’s always worth paying that bit extra for large, plump, firm, high-quality bulbs free of obvious blemishes and sourced from a reputable supplier. Along with most of those mentioned above, recommended stockists include most good Irish garden centres and peternyssen.com.

Make sure to plant these bulbs to the correct depth (typically roughly three times their own height), which helps protect their fleshy structures from temperature extremes and prevents them from drying out before they’ve had a chance to plunge their roots into the ground.

In gardens where raiding squirrels are a serious problem for freshly planted bulbs, it’s best to plant them in informal groupings and then place a protective layer of fine-gauge chicken wire over them (13mm-25mm openings, using the larger size for larger bulbs) before backfilling with soil. The same technique can be used for pots. Alternatively, make a small protective cradle of chicken wire to contain the bulbs before planting them to the correct depth.

Meanwhile, if you delayed doing so last month because of concerns about the negative impact on plants of this summer’s drought and intense heat, be reassured that beech, hornbeam, thuja and Leylandii hedges can all be given a final clipping so long as it’s completed by the middle of the month. So too can privet, yew and Lonicera nitida hedges.

September is also the ideal time to move or transplant conifers and other evergreen shrubby species. But it’s always a good idea to use a wind-filtering meshed fabric such as Bionet to protect the young plants against desiccating winter winds until their root systems establish, a process that will take at least until next spring.

Finally, consider planting up some containers using a mix of handsome evergreen and bulbous species for an eye-catching display that will give valuable interest through winter and into spring. Suitable evergreen species include grasses such as Carex buchananni, Chionochloa rubra and Carex testacea; ferns such as Polystichum setiferum and Polystichum polyblepharum; shrubs or sub-shrubs such as fatsia, Euphorbia wulfenii, camellia, skimmia, pieris, pittosporum and culinary bay; plus trailing ivy. Winter might still feel a very long way away, but when the days shorten and the temperatures begin to bite, your future self will thank you for it.

This week in the garden 

Keep deadheading dahlias to prolong their display and to protect emerging flowers from damage and disease.

Reduce watering of glasshouse and polytunnel crops such as tomatoes, aubergines, peppers and cucumbers to a minimum and remove any dead, damaged or decaying leaves or fruit to maximise productivity and plant health.