Gardening: Get next summer all sown up

One of the valuable gardening lessons that this summer’s fierce drought taught me as a flower farmer florist – and it taught me quite a few – is the importance of sowing hardy flowering annuals in early autumn rather than the following spring.

Autumn-sown annuals, you see, are far bigger, stronger, earlier-flowering, longer-flowering and more floriferous than their spring-sown equivalents. Given the great luxury of time to establish deeper, more extensive root systems, they can cope far better with less-than-ideal growing conditions. So instead of puny spring-sown cornflowers (Centaurea cyanus) forced to hurtle swiftly into summer bloom, you get large robust plants as high as your chest. Instead of weedy-looking love-in-a-mist (Nigella), you get stems that are strong and long enough to cut and put in a vase. The same goes for Ammi visnaga and Ammi majus as well as Orlaya grandiflora, all lovely, frothy "fillers" in a border or flower arrangement with their umbels of pale flowers reminiscent of cow parsley.

Other hardy flowering annuals that are far better from an early autumn sowing include larkspur (Consolida sp), the greater quaking grass (Briza maxima), annual scabious, Salvia viridis, honeywort (Cerinthe major) and various species of poppy including Shirley poppies (cultivated forms of Papaver rhoeas) in pastel shades of white, dusky pink and blush, and the Californian poppy (Eschscholzia californica), which comes in shades of gold, raspberry-pink and salmon. Pot marigolds (Calendula) also do very well when sown this way and in fact can often be seen happily self-seeding themselves around the garden at this time of year. Sweet pea are yet another example of a hardy annual that's much better for an autumn sowing, although it's best to delay sowing these until late autumn.

Propagate

How to propagate these plants? You can either sow the seed directly into well-prepared, weed-free ground, or into modules for transplanting later this autumn or next spring as young plants. The advantage of the former is that it saves on labour (there’s no need to prick out and transplant seedlings) as well as on compost and time, while it’s also better suited to certain species (Nigella is a good example) that resent any sort of disruption to their root growth. The disadvantage (why is it that there are always disadvantages) is that it’s more difficult to protect the emerging seedlings from pest damage, competition from vigorous weeds and weather extremes, while they’ll also need to be carefully thinned to a suitable spacing to allow them grow strong and big without competition from neighbouring plants.

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In comparison, sowing into modules/trays allows you to more easily monitor the emergence of young seedlings as well as to protect them from pests and diseases and to make sure that they get the best conditions for optimum growth. Its downside is that it’s more labour-intensive, more costly in terms of seed compost and as mentioned, not ideally suited to certain kinds of hardy annuals such as the aforementioned love-in-a-mist and poppies.

Before you rush off to buy and sow seed, it’s important to bear in mind the important distinction between hardy and half-hardy annuals. The first can tolerate a surprising degree of winter weather and frost so will happily endure an average cold Irish winter outdoors.

In comparison, the latter (examples include cosmos, nicotiana, tagetes and amaranthus) won’t tolerate any degree of frost, making them entirely unsuitable for autumn-sowing in this country.

If you do decide to direct-sow the seed, then it’s very important to prepare the ground well in advance. It needs to be completely free of weed growth and any kind of garden debris such as large stones, sticks etc, before being raked to a fine, crumbly tilth. You’ll also need to take precautions against slugs, snails and birds, which may eat both the seeds and/or emerging seedlings. Damp (but not sodden), warm, fertile, friable, free-draining soil in full sun or light shade offers the best conditions for rapid germination. So if yours is heavy, poor-draining and cloddy, then improve it before sowing by working in some coarse horticultural grit and some garden compost or very well-rotted manure. But bear in mind that poppies like a free-draining soil that’s not overly rich in organic matter.

If you prefer the idea of sowing into pots/modules for transplanting later this autumn or next spring, then make sure to use a good quality seed compost and to dampen it before sowing. After sowing, place the pots/modules in a shallow tray or bucket half-filled with tepid water to allow the compost to “drink” before covering the surface with a lid or sheet of glass or clear plastic bag. Don’t forget to label each pot or tray with the name of the variety and the date as well as the seed supplier. Then place the pots/modules somewhere bright where they’ll be in gentle heat; a glasshouse, polyunnel or heated propagator is great but they’ll also germinate successfully at this time of year if left outdoors on a garden table. You should see signs of germination within 7-10 days.

Seeds of most of these hardy flowering annuals are available from good Irish garden centres as well as from specialist online suppliers such as seedaholic.com, mrmiddleton.com, sarahraven.com  and chilternseeds.co.uk. But if you already grow some of these pretty plants in your own garden (or have a gardening friend who grows them), then don’t forget that seed is ripening on many hardy annuals at this time of year and can be collected in abundance and for free, proving once again that there are few things as generous as nature.

This Week in the Garden

Spring bulb planting season will soon be upon us so it's great to see suppliers beginning to take notice that many gardeners are asking for organic/ sustainably-produced bulbs free of environmentally damaging chemicals such as neonics. In Ireland, Cork-based Fruithill Farm offers a limited range while they can also be sourced online from UK-based suppliers including the Organic Gardening Catalogue. Well-known British bulbs supplier Peter Nyssen also recently announced that its entire range of tulip bulbs is guaranteed free from neonicotinoids (peternyssen.com).

September is a good time to take semi-hardwood cuttings of many kinds of plants including shrubby evergreens such as rosemary, sage, lavender, box, escallonia, holly, viburnum, hebe, camellia, ceanothus, cistus and choisya. Always use a sharp, clean secateurs, making sure to collect the plant material (roughly 10cm-15cm long, non-flowering shoots) in the morning and to choose a healthy parent plant free from pests or disease. It’s also important to prepare cuttings as quickly as possible after collecting them by stripping off their lower leaves and then very quickly “planting” them into pots filled with good-quality seed-and-cuttings compost (roughly five cuttings per pot). Water the pots, seal each pot inside a clear plastic bag sealed with an elastic band and then place them on a heated propagator out of direct sunshine. It’s also always a good idea to carefully label your cuttings to include the date they were taken, along with the name of the parent plant and the garden it came from.

There’s still time to make sowings of some winter vegetables for the polytunnel including winter lettuce varieties, oriental salad leaves, land cress, Florence fennel, broccoli and kale. Recommended seed suppliers include brownenvelopeseeds.com, greenvegetableseeds.com and seedaholic.com

Dates for Your Diary:

Today, Saturday, September 8th (4pm): Shankill Castle & Gardens, Paulstown, Co Kilkenny: Designing & Planting Your Garden, a talk by Irish garden designer Arthur Shackleton, admission €15, see shankillcastle.com for details.

Tomorrow, Sunday, September 9th: The Phoenix Park Visitor Centre, Phoenix Park, Dublin, the Annual Phoenix Park Honey Show in association with the Federation of Irish Beekeepers and the OPW, with competitive exhibits, tours of Ashtown walled garden and beekeeping talks, see phoenixpark.ie.

Saturday, September 15th: Mount Venus Nursery, Autumn Plant Sale with up to 40 per cent off some plants, see mountvenusnursery.com.

Sunday, September 16th (10am-5pm): The Walled Garden, Tibradden, Mutton Lane, Dublin 16, Fruitlawn Gardens, Abbeyleix, Co Laois, Garden Open Day & Plant Sale with rare and unusual plants for sale from Arthur Shackleton as well as Angela Jupe of Bellefield House, admission €5, see arthurshackleton.com for details.

Sunday, September 16th (11am-4pm): Fota House and Gardens, Carrigtwohill, Co Cork, Irish Specialist Nursery (ISNA) Plant Fair (the last of the 2018 season) with specialist plant sales by many of Ireland's best nurseries, see irishspecialistnurseries.com.