It’s at this liminal time of the year – a seasonal change of nature’s gears as old as the planet itself – that the line between summer and autumn starts to become blurred. Growth slows, days shorten, leaves begin to colour up, and many plants – but not all – turn their energies towards the ripening of seeds and fruit rather than fresh growth and flower production. For gardeners, it’s also a time for savouring that special mellow beauty of the early autumn garden, while simultaneously trying to plan ahead. With all this in mind, here are some handy little pointers to help you do both.
Deadhead and liquid feed
Perhaps more than anything, a combination of strategic deadheading and liquid feeding is key to keeping the show on the road for as long as possible. In this way, plants’ energies are both boosted and diverted from seed production. I say “strategic” because it won’t produce useful results with all plants. But it will certainly help to greatly extend the flowering period of summer bedding (especially container-grown plants) as well as late summer/autumn flowering plants such as dahlias, amaranthus, chrysanthemum, roses and asters. Used on kitchen crops such as French beans, mangetout and tomatoes, it will also have a similar marked beneficial effect.
Just make sure to avoid synthetic feeds and instead either use your own or go for a high-quality natural product. I alternate between home-made nettle feed and Health-Sea liquid seaweed feed, a concentrated extract made from seaweed (Ascophyllum nodosum) that’s sustainably hand harvested off the Irish Atlantic coast and approved for organic use (fruithillfarm.com). Other options include home-made compost tea (just dunk a perforated bag of home-made compost in a bucket of rainwater for 1-2 days and then use the water as a feed, diluting it to the colour of weak tea. These kinds of natural biostimulants help to protect against disease as well as boosting plant growth in multiple ways, including fruit and flower production.
Boost soil health
In the kitchen garden or allotment, early autumn is also a good time to protect soil health and boost fertility by sowing green manures or mulching recently emptied beds. Bear in mind that often-quoted mantra of organic gardening, which is that “bare soil is bad soil”. Also bear in mind that nature abhors a vacuum and will very quickly colonise any areas of bare ground with a fast-growing carpet of weed seedlings, creating more work down the line when the time comes to replant.
A wide variety of green manures are suitable for direct sowing in late August, including phacelia, red clover, crimson clover, winter tares, buckwheat and mustard (seed stockists include mrmiddleton.com; fruithillfarm.com and quickcrop.ie). Suitable organic mulches to use as a protective, weed-suppressant winter blanket over bare soil include home-made garden compost, well-rotted manure, grass clippings, straw, chipped hedge clippings, fresh seaweed (only use this if harvested sustainably and with permission), and commercial products such as Envirogrind (see envirogardenandhome.com and quickcrop.ie), Gee-Up and Enrich (see geeup.ie; enrich.ie and landscapedepot.ie).
Protect from disease
Keats may have called autumn “the season of mists and mellow fruitfulness”, but it’s also naturally a time of decay and plant disease. Along with using liquid feeds as described above, vigilance is key to preventing the latter from shortening the flower power of your favourite dahlias or killing off your tomato plants before the fruit has fully ripened. This means regularly and carefully handpicking and bagging any obviously diseased leaves, fallen petals or decaying flower heads to prevent the spread of moulds and rots. Special attention should also be given to glasshouses and polytunnels in terms of generous ventilation and cautious watering (do the latter in the morning, ideally only to the roots unless liquid foliar feeding, and avoid overwatering).
Order spring bulbs
Now is also the best time to order spring-flowering bulbs such as daffodil, tulip, crocus, fritillaria, scilla, ranunculus, anemone, chionodoxa and hyacinth, while stocks are still high and the availability of the most desirable varieties is still guaranteed. Many won’t need to be planted until late autumn (don’t plant tulips until November), but can be stored in a cool, dry shed until needed. The exception is daffodils (narcissus) which greatly benefit from being planted in September. Recommended stockists include Dublin-based mrmiddleton.com and UK-based peternyssen.com.
Fill the holes
Early autumn is also a good time of the year to assess your garden in terms of possible holes in the planting that could be usefully filled with some late-flowering or ornamental fruiting/berrying plants to extend the display well into October. This includes varieties of Hydrangea paniculata, an ornamental deciduous shrub whose large, showy, long-lasting flower panicles are a delight at this time of year, often deepening in colour as the season progresses.
Examples include Hydrangea ‘Limelight’ (lime-green, then pink); H. ‘Pinky Winky’ (white, then deep pink), and H. Wim’s Red (white, then pink, then deep red). Other floriferous, long-flowering species guaranteed to add generous colour to the autumn garden until the first killing frosts include many kinds of ornamental salvia (examples include S. ‘Amistad’; S. Hot Lips’ S. ‘Wendy’s Wishes’); varieties of agapanthus, aster, sedum, chrysanthemum, dahlia and agastache; Verbena bonariensis and Rudbeckia ‘Goldsturn’.
Collect and sow seeds
Finally, early autumn is traditionally a time for both seed collecting and seed sowing. Choose a dry, still day to do the former, handpicking into labelled brown envelopes (if possible, list the variety, date and a brief description) and then placing these in a cool, dry, dark, rodent-free place under cover until you’re ready to prep them. Many varieties of both ornamental and kitchen garden plants are suitable for home saving, the exception being F1 or F2 hybrids.
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If you’d like to find out more, then the Irish Seed Savers Association is hosting a practical workshop on seed saving at its headquarters in Scariff, Co Clare next month, which will be given by the respected Cork-based organic seed producer and grower Madeline McKeever (irishseedsavers.ie).
As for seed sowing, late August/early September is an excellent time to sow seed of many kinds of hardy ornamental annuals including nigella, ammi, cerinthe, consolida, snapdragons and English marigolds. If you have a polytunnel or glasshouse, then these will all benefit from being grown under winter cover. So will some early autumn-sowed leafy food crops such as chard, kale, winter lettuce varieties, claytonia, lamb’s lettuce, landcress, rocket, chervil and coriander.
This week in the garden
Ponds and water features can often run low of water at this time of year as a natural result of evaporation. Keep them topped up, but make sure to use harvested rainwater, as tap water can disturb the natural balance and result in algal growth, as well as causing the temperature to suddenly plummet at the expense of pond life.
[ Reflect on nature in all its glory with a garden pondOpens in new window ]
Take cuttings of tender perennial bedding plants such as fuchsia, pelargonium and osteospermum to grow on under cover in a frost-free glasshouse or cool porch. Hardwood cuttings of many kinds of ornamental shrubs can also be taken in the coming weeks.
Dates for your diary
- Blight & Bounty: Glasnevin in the Famine Years: Guided tour at the National Botanic Gardens, Glasnevin, Dublin 9; today, Saturday 23rd and Wednesday 27th, pre-booking through eventbrite.ie essential, tickets €5.
- Irish National Vegetable Championships at the Moate Agricultural Show: The Showgrounds, Moate, Co Westmeath; Sunday, August 24th (10am-5pm). See nvsuk.org.uk
- Delgany and District Horticultural Society’s annual Dahlia Show: St Patrick’s Primary School, Church Road, Greystones, Co Wicklow; Saturday, August 30th. All entries are welcome but must be submitted in advance by email to the show secretary at ddhs.showentries@gmail.com on or before Thursday, August 28th. See the society’s Facebook page for further details.
