Undercropping Asparagus?

[anubeon]

Greetings All,

I started a raised bed of asparagus last year and I was wondering if there were any beneficial 'companion' plants (e.g. green manures) which could be used to 'undercrop' (if that's the correct turn of phrase) the plants.

Obviously growing asparagus leaves a fair amount of bare soil which is prime real estate for weeds (in our garden its wood sorrel, amongst others, that fills that gap) and I'd rather cut down on weeding to minimise disturbing the asparagus' shallower roots. I'm not looking to grow any crops per se, as I'm sure the asparagus plants wouldn't welcome the competition, but I was wondering whether there were any low or matt forming nitrogen fixers which might serve the asparagus plants well (i.e. put more nitrogen into the soil than they take out?) whilst simultaneously squeezing out the weeds (I love the taste of wood sorrel, but it's a bugger to weed once it's established, and it gets everywhere in our garden).

I'm rather new to gardening, so I'm net entirely au fait with nitrogen fixation and green manure. I know that green manure strategies typically involve growing a nitrogen fixer such as red clover in the off season and then digging the plants in. However, do nitrogen fixers have a NET beneficial impact whilst growing as well? This was my reasoning for the above.

[Jeanied]

The problem with asparagus is that it hates root disturbance and competition from weeds. If you tried growing green manures you would have to dig them in and that would harm the roots of your asparagus crowns. The only solution I can think of for you is to use chopped plants as a mulch on the bare soil - and see if you can source some well rotted manure for the beds as well.

[RaptorUK]

Greetings All,

I started a raised bed of asparagus last year and I was wondering if there were any beneficial 'companion' plants (e.g. green manures) which could be used to 'undercrop' (if that's the correct turn of phrase) the plants.

I had the same thoughts as you . . . a Nitrogen fixer would seem to be the obvious choice but I'm not going to risk my Asparagus without some pretty substantial recommendation from someone who has already done it, I search the net but didn't find anything.

I have some Fenugreek which I will be sowing next week when I clear the last dregs of my Broadbeans, perhaps it would be an option, the RHS says it won't fix nitrogen in the UK.

[anubeon]

The only solution I can think of for you is to use chopped plants as a mulch on the bare soil - and see if you can source some well rotted manure for the beds as well.

I do have to 'earth up' a little more sometime this year as the soil level has dropped through settling, and I also have some wood-chip/bark mulch which I had intended to add this autumn. I suspect that the the later will certainly provide some protection against wood sorrel at least.

It'd still be nice to have a generous matt forming, perennial and evergreen companion plant that'll be a boon (or at least negligible) to my asparagus plants. Is that too much to ask for? ;-)

I had the same thoughts as you . . . a Nitrogen fixer would seem to be the obvious choice but I'm not going to risk my Asparagus without some pretty substantial recommendation from someone who has already done it, I search the net but didn't find anything.

I think the determining factor must be whether or not the presence of symbiotic azobacteria (the source of all nitrogen fixation?) more than compensates for the effect on established root systems and broader soil fertility. Like you I've searched far and wide and found nothing definitive, although I did locate a study on inter-cropping asparagus with legumes, which unfortunately due to the ever parasitic nature of closed access journals in inaccessible to the hoi polloi*.

The other issue is that many of the green manures and other nitrogen fixers I've heard of are themselves annuals (at least in the UK) and so they'll need to be pulled if not incorporated once they expire anyway (although I suppose one could leave them in place to self-mulch). As Jeanied says, asparagus doesn't like root disturbance, Although does this become less of an issue as the bed establishes and develops deeper roots?

Thanks for the responses, hopefully someone who's been brave and tried something like this will come along shortly. :-)

Regards,

Lee

* It's scandalous really if you think about it. Often publicly funded research, written up by University academics on behalf of for-profit enterprises, who demand copyright over any paper, pay neither the author (their primary and in many cases sole content creators) nor the peer reviewers (to whom they are reliant for the entire business model) and whom then lock away the research behind pay-walls.

[ButternutSquash]

If you have a hedge, then shred the prunings and use as mulch. I am sick of shredding my bloody 20 metre hedge. Each year I do it, and hate it. I still have to reduce the height by a metre. If you do not have a hedge, your neighbours would be overjoyed to get rid of trimmings. And it is far greener than buying in mulch.

[anubeon]

If you have a hedge, then shred the prunings and use as mulch. I am sick of shredding my bloody 20 metre hedge. Each year I do it, and hate it. I still have to reduce the height by a metre. If you do not have a hedge, your neighbours would be overjoyed to get rid of trimmings. And it is far greener than buying in mulch.

We certainly have a regular supply of privet cuttings, although I've been using them mostly to balance out the green/brown ratio as well as to aerate my compost piles. I should have a load due in a weeks so I'll mulch the Asparagus bed with them then.

I have heard that adding 'green' mulches, such as mowed grass and recent hedge cuttings, can deplete nitrogen in the underlying soil. Is there any truth to this and if so is there are way to mitigate the effect?