URBAN FARMER:It takes four years for asparagus to reach harvesting stage and growing it will put your patience to the test
THE BRITISH gardening writer, Sarah Raven, calls it “one of the most life-enhancing plants to grow”; Jamie Oliver refers to it as “one of the most nutritious vegetables you can eat”; while the food writer, Jane Grigson, wondered why gardeners everywhere don’t automatically plant a bed of it.
Three cheers, then, for asparagus, because it seems that these plump, lime-green and delicately flavoured spears, which are in season right now, are both delicious and good for you.
Vitamins B6, A, C, E and K; calcium; magnesium; zinc; folic acid (lots of it); potassium; copper; manganese; and selenium – asparagus has them all, making it one of the most nutritionally balanced of all vegetables. Rich in soluble fibre and low in calories, it’s also traditionally been considered an aphrodisiac.
But nothing is perfect and asparagus also has a few definite downsides, such as its tendency to make urine smell distinctly odd (more about that later) and the fact that it takes an age (three years) to produce a crop of any size.
In the OPW’s walled garden in the Phoenix Park, the asparagus plants (the high-yielding Connover’s Colossal) were planted in mid-April 2009 as one-year-old “crowns”, the technical term for the squid-like roots of the plant. Bought dormant and bare-rooted, (without a covering of soil/compost), the crowns were then planted into wide, raised beds (20cm high) in a sunny, protected corner of the garden, where the weed-free soil had been previously enriched with loads of deeply-dug, well-rotted manure. Here, they were spaced roughly 30cm apart, with the roots carefully spread out onto ridges of soil before being covered in a deepish layer of soil.
Originally a native of the seashore, asparagus hates a wet, heavy soil and so the OPW gardeners also dug in loads of horticultural grit before planting. “The raised beds also help with drainage,” says OPW gardener Meeda Downey, before adding that the gardeners have “done very little to them since then, other than to hand-weed the beds and heavily mulch the plants with manure last autumn.
“In fact, we mulched the plants so heavily that we had to pull away some of the manure this spring – it had formed such a hard crust that we thought it might be stopping the young shoots from pushing through the soil,” adds colleague Brian Quinn.
While a handful of the young plants didn’t make it through the icy winter and cold late spring, the rest did, and they’ve now started producing succulent green spears that look oh-so-temptingly good.
“But we can’t cut them at all this year,” says Meeda with a shrug. “We have to let them grow their ferny leaves like they did last summer and let the root system establish itself properly. If we harvested the spears now, it would weaken the plants too much.”
Instead, the OPW gardeners must wait until next spring before they get their first asparagus harvest, and even then it will only be a meagre one. “You only harvest for a couple of weeks the second year after planting, so it will be the following year , before we can properly harvest the young spears, beginning in late April and right through the month of May into early June.”
In the meantime, Brian and Meeda will continue to keep the plants weed free and well fed.
“We sprinkled the organic fertiliser Osmo on the soil at planting time, and we’ll continue mulching the plants with manure in autumn,” says Brian. “After that, it’s just a case of letting the ferns go brown each year before cutting them back to about 7-10cm above the ground. You’re also supposed to keep an eye on the depth of soil, as asparagus crowns tend to rise out of the ground a bit as they mature. The ideal depth is about 12-15cm below ground.”
While it’s clear that patience is a necessary virtue when it comes to this vegetable, the rewards, as asparagus aficionados will testify, are both long-lasting and plenty. Once well-established, these perennial plants can be productive for anything up to 20 years, amply repaying the initial efforts made in carefully preparing the site.
Harvesting, it should be added, is another art in itself, as the asparagus spears or shoots should be carefully cut about 5-7cm below ground, and when they’re about 12-18cm long. There are even special knives for this – check out Suttons (suttons.co.uk) which sells an asparagus knife with a curved, serrated, 25cm blade.
The only problem, as impatient gardeners soon discover, is avoiding damage to nearby roots and shoots while you do so.
And that funny smell I mentioned earlier? The one that makes some people’s pee smell funny or, as the writer Proust put it rather more poetically, the smell “that changed my chamber pot into a flask of perfume”.
Well, originally it was believed that only a certain percentage of the population metabolised asparagus in this way, resulting in that distinctively sulphurous smell, while the majority of us didn’t. Those who did were termed “excretors” by scientists researching the phenomenon, until they realised this wasn’t the case at all. Instead, almost all of us metabolise asparagus in the same way, and produce the same chemicals that create Proust’s distinctive “perfume” – the key difference lies in our ability to smell the chemicals.
Some 22 per cent of us, it appears, share that dubious distinction, but don’t let that put you off planting one of the true aristocrats of the vegetable garden. While it’s now (just about) too late to plant the bare-root crowns, you still have time to plant out potted plants, which are available in most good garden centres – just remember to keep them watered during any dry spells until well established.
If this sounds too laborious, then it’s a case of waiting until next March to plant out the crowns, with the prospects of a decent harvest some time in 2014. Yes, four years is a very long time to wait for your own asparagus, but just think of the decades of glorious gluttony that should follow and it will all seem worthwhile.
- A revised edition of the book by Stephen Alexander of Teagasc, A Guide to Vegetable Growing, is available free. For a hardcopy, contact Stephen at Teagasc, Malahide Road, Kinsealy, D17 (01-845 9048), or for a PDF version go to teagasc.ie where it's listed under publications
- 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. Open daily from 10am to 4.30pm
- Next week: sowing peas
- Fionnuala Fallon is a garden designer and writer
