4 May 2024

Edible Gardener Kath Irvine: everything asparagus

From Saturday Morning, 9:45 am on 4 May 2024

When it comes to growing asparagus at home preparation and patience are key, says gardening expert Kath Irvine.

Asparagus growing in Horowhenua

Photo: Supplied

It’s not a difficult crop to grow, she tells Susie Ferguson, but the home gardener often rushes in without sufficient planning.

“Before you prepare your ground, take a minute to understand what does asparagus need? And wild asparagus is a good pointer.

"So where does that grow? It grows in dunes and lowlands mostly around the coast and mostly around drier places. And that's our first clue.”

Good drainage, therefore, is absolutely essential for happy asparagus.

“Because it's a spring crop, we want to think how is our ground in springtime, and often in springtime there's an awful lot of people who have heavy clay and it's very wet in spring, so you definitely want to make a raised bed in that scenario.”

Because asparagus is coming up in mid to late spring find a spot with good sun at that time of year, she says.

“It's a perennial, so that's going to be there if you prepare it well, you've got 20 years of picking asparagus. “

So how to best prepare it the asparagus bed?

“People think it needs free drainage and I'm on heavy clay soil, add sand, really what you create then it's kind of like cement. Your best bet for drainage is to elevate and to add organic matter to your soil, homemade compost is the very best.”

You can aerate the bed with a fork first, she says, or get a specialised fork with extra-long tines.

“It's very different to digging, you just slide it and push it and pull it back and you're just cracking it open and getting that much needed air into it. Then you start layering up on top of that loads of organic matter and seaweed.”

Make a big stack of organic matter now and it will be well rotted by spring, she says.

"In spring when you're when your local asparagus grower or someone local that grows asparagus are selling crowns of asparagus, pop off to the farm and grab a whole lot and your bed is all ready to go.”

Because asparagus is perennial, deal with any stubborn weeds before planting, she says.

“It has a really fibrous root system, you get rid of any pernicious weeds first and by pernicious I mean the really hard dug-in ones like butter cup and dock whatever it is at your place.

“Clean those out first because you don't want to be managing them afterwards.”

If you have an established bed it’s still time to get prepared to maximise next spring’s season.

“When the spears finish in early summer, usually they head off and create these beautiful big ferns.

“And they are very flippy-floppy, I manage them through the season with short bits of bamboo and just run a string line and just hold them up so they don't get in my way and drive me nuts.

“These will start to die off as the cold hits. As soon as they've gone completely brown, which will, you know, be in winter sometime, just break them off, they just break off.”

A weed at this point is useful, she says.

“Way better to do it now because asparagus is so breaky, when the new spears are coming through, you really don't want to be weeding around that because you can knock them off so easily.”

Once the weeds are clear, layer up with a homemade mulch, Irvine says.

“Because it's a perennial I'd favour on a mulch that is veering more towards dry stuff. So, I wouldn't be mixing fresh grass clippings through my asparagus mulch, for instance, I'll be using more hay or even some lovely mixed woody chip or arborist chip.”

It’s a short season and once the fat spears are finished, she says, it’s best to avoid picking the skinnier ones.

“You're wanting to support the perennial to keep on going. So, at times you have to make those tough parenting calls, right we're going stop [picking] now.”