This year’s weather has resulted in a spectacular strawberry crop in the walled garden

In the unlikely event that you’ve ever stopped, if only for a second, to wonder exactly how much space would be needed to grow 600 strawberry plants, I can tell you that it’s rather a lot, requiring something close to the size of a small town garden.

But when, like OPW gardeners Meeda Downey and Brian Quinn, you’ve got a large, 2.5 acre Victorian kitchen garden that’s roughly one-and-a-half-times the size of an average football pitch, you don’t have to worry about such inconsequential matters. Instead, you think big. “Thinking big” is the reason Meeda and Brian are now in the wonderful position of being ankle-deep in thousands of sweet, ripe strawberries, all the more so because the baking hot summer sunshine has encouraged the plants (all 600 of them and all at once), to produce a sudden glut of fruit.

The gardeners, unsurprisingly, aren’t complaining. “They’re really delicious, every one of them,” grins Meeda, when asked to name her favourite of the three strawberry varieties (Cambridge Favourite, Elsanta and Eros) that are growing in the walled garden.

“My favourite strawberry is a ripe strawberry,” says Brian by way of confirmation. “And to be honest, the varieties that we’re growing have got a little bit muddled over the last few years anyway, because we tended to pop in ‘runners’ (young offshoots of the parent plant) wherever we saw a gap or wherever a plant had died.

“So it’s sometimes hard to be sure what variety we’re actually eating. The most vigorous of the three seems to be Cambridge Favourite but they’re all doing well for us.”

All three strawberry varieties the OPW gardeners are growing are classified as mid-season, meaning that a flush of fruit is produced over a period of two to three weeks but is then finished by mid-summer.

Cambridge Favourite, the earliest fruiting of the three, is one of the best known modern strawberry varieties and a reliable cropper, with large, tasty, crimson-coloured, wedge-shaped fruits.

Elsanta is the high-yielding, long-lasting, Dutch-bred variety that superseded Cambridge Favourite as the popular choice among professional strawberry growers (hence it’s often seen for sale in supermarkets), although neither this nor Cambridge Favourite gets top score for disease resistance.

Eros, the last of the three varieties being grown by Meeda and Brian, is the offspring of a cross between Elsanta and another variety called Allstar and is also a highly productive variety that’s popular with professional growers.

But all strawberry varieties are terribly vulnerable to viruses that gradually weaken the plant to cause a slow decline in health and productivity, or worse. In fact, so vulnerable are the plants that in his book, Forgotten Fruits, the author, Christopher Stocks, refers to strawberries' "genetic Achilles heel: their susceptibility to viral infection".

It’s the reason why so very few “heritage” varieties of strawberry have survived from the past (Tomkins refers to these lost plants as the ghosts of another age), as well as part of the reason why modern breeders place such an emphasis on disease-resistance.

As old varieties succumb, they need to be replaced, and so every year, thousands of new strawberry varieties are trialled on the basis of taste, vigour and disease-

resistance, with very few making the grade.

There’s one, however, called Albion, that has proved to be a big hit with both growers and strawberry-lovers since it appeared a few years ago, so much so that it’s already becoming the most popular choice among organic growers. Classed as an “everbearer”, Albion starts fruiting in May and continues to do so in several flushes throughout the summer and into October. On its website, Thompson & Morgan describes the fruit as “mouth-wateringly sweet” whose “big dark-red berries stay delicious and juicy throughout the summer”. It’s also a very healthy variety that shows excellent disease resistance, making it the perfect strawberry variety in many people’s eyes.

• 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 the Urban Farmer will cover growing salad leaves

• Fionnuala Fallon is a garden designer and writer