What to do when it comes to the crunch

Celery is a crop on the rise, and if you take a few precautions, growing it can be simplicity itself

GIVEN its evocative name, and the fact that it’s growing in what is, after all, a restored Victorian garden, visitors to the OPW’s walled kitchen garden could be forgiven for thinking that the neatly planted patch of Celery Victoria is a classic example of a “heritage” vegetable variety dating back to the 19th century.

All the more so when you consider what staunch royalists so many of the great Victorian nurserymen and plant breeders were, especially when it came to naming many of their newly introduced varieties of vegetable and fruit in honour of the recently crowned Queen Victoria and her consort Prince Albert.

For example, the patriotic English nurseryman Joseph Myatt, gave gardeners Rhubarb Victoria (1837) and Prince Albert (1840), while Suttons Seeds catalogue of 1852 (this long- established seed company was founded in 1806), includes varieties of pea such as Queen of England, Carter’s Victoria and Victoria Marrow.

In the case of Celery Victoria, however, the name is most definitely a red herring when it comes to any clues about its origins. For instead of being Victorian, this F1 hybrid (the very first celery F1 hybrid) is a child of the late 20th century, and the result of very modern breeding techniques. A relative stripling in the vegetable world, it was introduced to gardeners by Dr Peter Dawson of the British company Tozer Seeds in 1991.

Yet, despite its status as a newcomer, Victoria has already firmly established itself as a particular favourite amongst both commercial and private growers. In his recent book, Vegetables for The Irish Garden, Klaus Laitenberger describes it as "an excellent variety, great flavour, high quality and long-standing ability", meaning it lasts better in the vegetable plot than other varieties once it's reached maturity. The garden writer, Joy Larkcom, also singles out Victoria as a celery cultivar especially worth growing, as does the vegetable expert, Medwyn Williams.

In the walled garden, OPW gardeners Meeda Downey and Brian Quinn have also found Victoria to be a relatively trouble-free crop in comparison to other celery varieties. But having said that, the gardeners held a very powerful trump card in their hands when it came to defeating one of celery’s very worst pests, the dreaded slug.

“Last year, slugs destroyed the celery crop,” remembers Brian. “They hid deep inside the plants where you couldn’t see them and just munched away to their heart’s content. It was only when it came to harvesting that we realised the extent of the damage – they’d eaten little tracks right through almost every one of the stalks.

“So this year, we were determined to make sure they didn’t get away with it and we used the biological control Nemaslug, which contains nematodes that are the natural predators of slugs. It worked brilliantly – there’s virtually no slug damage at all on this year’s celery plants.”

“Part of the problem is that we’ve found with the celery plants that you have to keep them well-watered, otherwise they just gets tough and stringy,” adds Meeda. “But regular watering just encourages the slugs even more.”

Those urban farmers who are in any way squeamish may not enjoy reading exactly how Nemaslug works (if so, skip to the next paragraph), for it does so by virtue of thousands of microscopic eelworms (called Phasmarhabditis hermaphrodita) that release a deadly bacteria inside the body of the slug.

“Yuck” might be the initial reaction of most gardeners, but less so when you realise just quite how effective this organically acceptable biological control is, and even less again when you discover that it’s harmless to bees, wildlife, animals and humans. So forget beer traps, bran, coffee grounds, broken eggshells, copper strips or even copper-based slug pellets – as far as Brian and Meeda are concerned, Nemaslug outdoes them all when it comes to killing one of the gardener’s most hated pests.

But, brilliant as it is, Nemaslug does have some downsides. For one thing, it’s expensive – the standard packet, which costs €17.95 from Mr Middleton (mrmiddleton.com) is only enough to treat 40sq m, and lasts for just six weeks after application. Secondly, its effectiveness is dependent upon certain conditions – it must be applied in a solution of water onto damp soil, and where the ground temperature is above 5°C at the time of application. Be warned, also, that the product is less successful when used in gardens with waterlogged or heavy clay soils, while it shouldn’t be used very close to garden ponds as it may affect water snails. Finally, Nemaslug isn’t that effective against the really big slugs, which are those monsters (usually the Black Slug) that are more than 7.5cm long.

Having said all that, if your vegetable plot suffers badly from slug damage, Nemaslug is certainly well worth considering, even for occasional use, particularly given the speed with which these pests multiply.

The Grey Field Slug, for example, which is one of the most damaging slugs in Irish gardens and can be active above ground even on mildish winter days, is estimated to produce something in the region of 90,000 grandchildren per individual slug, while other experts reckon that just one acre of farmland can harbour up to a quarter-of-a-million slugs.

Now – as autumn arrives – is a particularly good time to consider using this biological control, because most slugs that are resident in your fruit and vegetable patch are busily laying their eggs. These will overwinter before hatching out next spring just in time for the young slugs to feed on new plants. Slugs, in particular the Keeled Slug, can also be especially damaging to potato crops at this time of year, and the more so the longer that the crop is left in the ground.

Back in the walled garden, the OPW gardeners are busily harvesting their beautifully slug-free celery crop before the first frosts arrive. Ideally, as Klaus Laitenberger points out in his book, this should be done early in the morning when the plant is at its freshest.

Cut away the foliage with a sharp knife to leave about 25cm of stem, and (like all vegetables) ideally eat or cook the sweet, crunchy stems as soon as possible. Having said that, the stems will keep for a couple of weeks if kept bagged in the fridge. And if you’re not a fan of celery, consider recent research that suggests that it’s a kind of “vegetable viagra” for any men that eat it.

Fingers crossed, you might well add, that the same isn’t true for slugs.

• The OPW's Victorian walled kitchen garden is in the grounds of the Phoenix Park Visitor Centre, beside the Phoenix Park Café and Ashtown Castle. The gardens are open daily from 10am to 4.30pm

• Next week Urban Farmer will cover growing pears

• Fionnuala Fallon is a garden designer and writer