Asparagus time

There is no crop more valuable than asparagus. Not just by financial measures either, though it can give good returns if sold, but also in terms of time, nutrition and flavour. Asparagus comes in very early when little else is productive, it is a green shoot packed full of vitamins and minerals, and that is why it tastes so good. Indeed it is one of the great gourmet pleasures and almost unchanged since Roman times; references and pictures show them eating asparagus exactly alike to ours today.

Asparagus is a native seaside plant found, though only rarely, around the coasts of Europe and the Mediterranean. Of course it has been picked since time immemorial; which is probably why it is so scarce now. Traditionally it would have often been mounded up with sand to blanch it. The French and most Continentals still prefer blanched asparagus which is white to pale yellow with a milder flavour and softer texture. In England we have long preferred the shoots exposed to the light which turns the tip end green (or in some cases purple) though the base is still partly blanched depending on depth of planting and any ridging practiced.

Although there are many varieties which vary slightly in colour and others varying to some extent in shape with slightly more pointed or rounded ends the flavour and texture are similar for all when grown on the same soil. Different soils do change the flavour marginally but the most important improvement is freshness and more sun which both make asparagus sweeter. Cut spears turn bitter and tougher within hours and standing old spears in water to revive them makes them worse!

There is only one pest that causes regular problems and that is a pretty little beetle, it’s the tiny slug like maggots of this that you find eating up the foliage in summer turning the fern into sticks. This weakens the crowns and loses us crop! The maggots can be killed with derris or other permitted dusts or sprays but a better solution is trapping them. If all plants are cut for spears save just one or two and these allowed to produce fern from the first then all beetles will be forced to lay their eggs on them. These sacrificials are then cut hard back and the fern burnt before cutting ceases removing all eggs and maggots from the first generations and knocking back the infestation considerably. The adults are also trapped in twiggy bundles left by the plants and burnt in early winter.

The major drawback with asparagus is the time taken to get the crop which takes two to three years. The bed needs to be well prepared and extremely well weeded before the young crowns are planted out as early in spring as the soil is workable. They then need at least two full years of strong growth to put on the reserves to enable them to crop. Even so cuts in the third and fourth years must be for only a short time or the plants may become too weakened.

Once the bed is well established cutting has to finish about six weeks after it starts so usually proceeds from the end of March till the beginning or middle of May in southern UK. Any longer and the plants are weakened. However providing you leave at least five or six strong shoots to become good fern on each crown you can steal any surplus spears which can give a small bonus picking every week or so into summer. Weaker crowns must have their shoots left to become fern from earlier on in the season. (If all the shoots from a crown are always spindly then that crown produces ‘sprue’ and needs eradicating and replacing by a better one.)

However once cutting commences it is important to cut all the shoots off each crown in order that more shall be produced; leaving poor and weak shoots to grow suppresses better ones. It used to be thought important to cut each shoot as close to the crown as possible, possibly to prevent rotting back. Now it is thought not so crucial and leaving stubs only detracts from the length of lower stem too tough to eat anyway. Leaving wee stumps above soil level may even be useful as indications of how many shoots each crown has thrown during the season.

The length of blanched stem can be increased by covering the crowns with a mound or ridge of soil. Simple enough to do this needs planning as dragging the surrounding soil for the purpose is only possible if it has been moved often enough to prevent the asparagus rooting into it. The root system is pervasive and may stretch for tens of metres each way in sandy soil though much less in light clay -and the roots soon die in waterlogged clay. Growing on the flat is widely practiced though it makes earthing up more difficult so this is then dispensed with. Mounding or ridging proportionately gives more blanched stem but as the crown is buried deeper this can make for a later or lighter crop. The benefit is maximized with a permanent ridge and furrow arrangement but this requires exceptional labour to maintain.

Mulching is also problematical, it can help with soil moisture retention in summer and suppress weeds but as it slows down the soil warming in spring it will also delay the shoots emerging. So it is wisest to incorporate as much humus forming material before planting as possible rather than applying heavy mulches later. However once the cutting has commenced with vigour well into the season it is possible to apply mulcheson pathways and between the plants though care must be taken not to rot the base of emerging stems by submerging them with anything rank. Rodents and slugs may also do more damage given the shelter of coarse mulches. Sharp sand deters slugs and is the safest mulching material over the crowns.

Covering the crowns with sharp sand marks the sites of the crowns, keeps them clean of weeds and enables the intervening spaces to be more easily hoed. This must be shallow hoeing so as not to damage the roots which are thick and spaghetti like. Asparagus being herbaceous dies down completely leaving no living part above soil level so I have found it convenient to flame gun the asparagus bed several times over winter right up until the shoots emerged; this cooked the weeds without disturbing the soil and saved most further weed control. Flame gunning once the shoots are emerging causes bent and twisted spears-as does hard frost.

As it is difficult to add compost or mulches once the bed is formed then any further soil enhancement has to take place with rock dusts, finely ground or pelleted fertilizers or liquid and foliar feeds and of these last seaweed spray is particularly beneficial. Two dressings are of especial use; soot and salt. Soot darkens the soil and brings forward the cutting time significantly; I dust mine on the surface from an old sock. Some may also wish to dress with salt as this is most traditional; it suppresses weeds and is said to improve the flavour but may cause soil greasiness on heavy clay. Most use of all though is a good watering during any dry periods from the start of the cutting season and on into early summer.

I have not mentioned spacing- this is contentious and variable. Those with rich moist soil can squeeze more plants into the same area. However the crowns expand and soon impinge on each other. I think it is foolish to plant closer than two per yard or metre in the rows with metre wide paths or thereabout. Wider spacing gives much bigger stronger crowns with bigger spears but less crop in total. Very cramped spacing gives slightly bigger crops of sprue; small shoots only good for soup. Commercial growers plant close, exhaust the plants early and dig them up. Gardeners usually plant wider and their beds then crop for longer with bigger spears.

The other way to bigger spears is not to grow the new all male F1 varieties. These have been bred to give large uniform crops of good sized spears per acre- but they do not give the biggest sprears. The shoots from female crowns are fewer but much fatter as they go on to carry the seeds. Thus if you want big spears and the total weight cropped per sq/m is less important then grow old mixed sex varieties and select for crowns with fat buds.

You can select fairly accurately from early on as the best crowns are usually already apparent after the first year. This is when they are dug and dispatched to you. It is a waste of money getting older than one year old crowns as though these are bigger they are slower to establish. It is better to spend the extra on buying more plants than you require, as soon as they arrive you can select the quality bigger stronger crowns with lots of fat buds on. Having choosen yours pass on the surplus to a friend.

The shipped bare root plants resent the digging, moving and drying out and need to be planted immediately, I dunk mine in seaweed solution while they are waiting their turn. Pot grown crowns are easier to deal with but every root must be teased out and spread carefully when planting. Separating a congested rootball is easiest by agitating it in a large bowl of warm water. The traditional way to plant the crowns is each on it’s own mound in a pit or trench. The roots flop over the mound whilst the buds on the crown are accurately held just under the soil surface and are not damaged whilst firming in the roots all around it. Then mark the centre with a spot of soot or sand so you can weed all round safely.

I have only mentioned planting crowns so far. This is the usual way, however in recent years more varieties of asparagus from seed have been offered and these have several advantages. Most of all the cost, they are cheap. Secondly by growing them yourself you can move them without much of a check. Further the very best plants are gained by sowing in situ and thinning at the end of the year. This does require superb weed control and the tiny seedlings are hard to spot. The best variety from seed I’ve found to be Gjinlim which outgrew all others to the extent that it looked as if it had a year’s advantage.

Indeed there is only one drawback with asparagus- there is never enough of it!