18 April 2015

Planting an asparagus bed

Asparagus is one of the classic spring vegetables, available for a couple of months from about early to mid April. These days asparagus can be found in the shops all year round, much of it imported from Peru. Imported asparagus rarely has the flavour of English asparagus in season. Sadly, English asparagus always seems to carry a hefty price tag, even in the middle of the season. I saw a bunch of English asparagus for sale in Borough Market recently, right at the beginning of the season, for £6. I counted the bunch, there were 7 spears. Much as I like asparagus, I am not really willing to pay almost a pound a spear for it.

The good news is, asparagus is not actually all that difficult to grow. An established asparagus bed should crop fairly prolifically. We used to have an asparagus bed and picked so much that we had to come up with imaginative things to do with it. The only downside to such a surfeit of asparagus was the funny smell it gave our pee more or less continuously for about six weeks.

Asparagus is a perennial vegetable, meaning that once planted it can stay in the same place and will crop year after year. Once established, an asparagus bed shouldn’t require too much work. The hard work is all up front. Patience and self-discipline are required to allow the plants to establish in the bed, as one must resist the temptation to harvest any spears in the first two years. 

March and April are the ideal months to plant out an asparagus bed, and the bed preparation can be done over winter. We recently moved, and I decided to plant a new asparagus bed. I started digging over the bed in February and planted out the crowns in March. Most people start an asparagus bed from crowns, essentially one-year old dormant plants. It is possible to grow asparagus from seed, but this will require a three-year wait before you can pick any. I decided to go down the crown route – three years is too long a wait.

Preparing the asparagus bed

A healthy asparagus bed can crop for 10 or even 15 years, and it is worth spending a bit of time on bed preparation. There are three things to think about when preparing the bed. First, getting organic matter into the bed, to ensure the plants have enough nutrients. Second, removing perennial weeds – asparagus doesn’t like competition. Third, removing stones and other debris from the ground. If there is debris in the ground, the asparagus spears will develop kinks as they hit stones in the ground as they grow, and (at the risk of getting all Frankie Howard on my readers) no one wants a bent spear.

I dug my new asparagus bed out of the lawn. This has the advantage that once the turf has been skimmed off, there shouldn’t be much of a problem with weeds. That said, the soil underneath grass can often be fairly compacted, which can make digging harder. I am a bit old fashioned when it comes to digging new beds, and often opt for double-digging. Essentially this means that the soil is dug over to a depth of two spade depths rather than the one that goes with normal digging. This eases soil compaction further into the soil, and allows the introduction of organic matter deeper into the soil. 

First, mark out your bed. I decided to plant 20 crowns, and dug a bed approximately 8’ by 4’6” (about 2.6m x 1.5m). Starting at the edge of your bed, use a spade to strip off two spade-widths of turf off the entire length of the bed. Put the turf to one side. The aim is merely to skim off the turf and its roots. You don’t want to take too much soil with it. Then dig out the soil from the entire area from which you have removed the turf. Put the soil to one side, preferably near the other side of your planned bed, as this soil will go back into that side of the bed. A builder’s hippo bag is ideal for containing the soil. Then add some organic matter into the bottom of the trench. I use 6X for this – which is essentially well-rotted concentrated manure - but you could use normal manure, garden compost or even leaf mould. Fork this into the bottom of the trench. Remove any large stones or other debris that you find. There’s no need to worry about every pebble from this second layer, just the larger ones. In the second layer, you will probably start to get into the subsoil, so you might find a lot of sand or clay, or in my case, a mix of sand, clay, chalk particles and flints, all debris that washed off the South Downs during the last ice age.

Once you have forked over the bottom of the trench, add a bit more organic matter, then skim about a spade-width’s of turf off the next length of your bed. Place the turf upside down in the bottom of the trench. Use a spade to break it up a bit. The turf will rot down in the soil providing more useful organic matter. Then work along your new line, digging the soil out and placing it on top of the turf that you have just skimmed off. It doesn’t matter if the earth is quite cloddy at this point, you can break it down later. In the interests of growing straight asparagus, pick out any large stones, bricks, broken bottles or and other debris that you find. You might find something interesting – I’ve found clay pipes, bullet casings, bottles and uniform buttons whilst digging over gardens. Then add more organic matter, fork over, and start a new row as described above. When you get to the final row of your bed, add the turf that you skimmed off the first row, followed by the soil that you dug out the first row.  Add some more organic matter to the top of your new bed. The time spent picking stones out can feel a bit tedious, but it is worth it.

If you have left plenty of time to prepare your asparagus bed, you can leave your bed like this for a while, as a combination of frost, wind and rain should start to break up the soil a bit. Once you get close to March, start breaking the clods down into smaller lumps of soil, removing stones as you go. I use a cultivator for this, which is one of those tools gardeners used in the old days, a bit like a pitch fork with curved prongs, but which don’t seem to be made any more.

At about this time, remember to order your asparagus crowns. Then dig two shallow trenches, each about 12” wide and 8” deep at either side of your bed. Leave a small mound down the middle of each trench. If you do this before your crowns arrive, you will be ready to plant them once they arrive, which is better for the crowns.

Planting the asparagus crowns

When they arrive, the crowns look like some sort of prehistoric sea creature. Spread their roots out, and place them across the mound in the middle of each trench, about 12” apart. Cover them with about 2” of soil, a bit of organic matter and water in well. Once you start covering the crowns it is particularly important not to get large stones in the bed. I used a garden sieve to remove any stones from the top soil. A few weeks after planting the crowns, you will suddenly see spindly asparagus spears appearing from the bed. Cover these with a couple more inches of soil (preferably sieved to remove stones) until they are covered again. Keep covering them in this way until the trench is full. I found that once the spears started growing, they grew pretty fast, and needed more soil pretty regularly. Water well.

At this point you will see lots of enticing asparagus spears in your new asparagus bed, and have to resist the temptation to pick any. By summer, the asparagus spears will have become huge fern-like fronds. On exposed plots, these fronds may need some support to protect them from high winds. Remove any weeds that grow in the bed by hand, taking care not to damage any of the asparagus crowns. In autumn, the asparagus fronds will die off, at which point they can be cut back, and the bed mulched. 

The following year, you will once again have to resist the temptation to pick any asparagus, but the year after that you can pick it for up to six weeks. In following seasons you can pick the spears for up to eight weeks. Each autumn, the asparagus fronds should be cut back once they have died off, and a mulch applied. The bed should be weeded regularly, as asparagus doesn’t do well with competition.


There’s much to be said for cooking asparagus simply – either steam or blanch it, and eat it with vinaigrette, hollandaise or melted butter. It is also good raw in salads, grilled on a barbecue, and makes a fine risotto. For something slightly different, try my recipe for asparagus fritto misto.

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