green manure – options to avoid digging?

[Jasper ShawParticipant]

Hi Charles,

In September, faced with the prospect of having many empty raised beds on my allotment over winter I decided to sow green manures on a number of my beds – Phacelia on 2 (Sown Sept 17th) and Mustard on 3 of them (Sown Sept 22nd).

At the time I thought I was being quite smart until it dawned on me that this is pretty much incompatible with the no-dig approach.

These seeds have germinated well and I have about 1 foot high leafy growth across the beds. It is quite mild here in London and I don’t expect there will be frosts soon or severe enough to kill of the mustard plants before they flower.

What I’d like to ask is if you were in this situation, what might you consider doing to rectify the beds in a way which is consistent with no digging?

I’ve thought that maybe I could…

1 – pull up all the green foliage (roots included) and compost this material before lightly mulching over what remains on the beds with some manure for over winter

2 – cut down the foliage on the beds and leave it insitu to rot down on the surface as a mulch over winter

3 – cover over the beds with plastic sheets to kill of the plants and let them rot down over winter

Any advice you might suggest would be kindly appreciated. I’ve attached a photo of the beds if that helps with making sense of my question.

Many thanks,
Jasper

[charlesModerator]

Hi Jasper and congrats on your lovely plot.
Mustard sown September may have time to flower before winter, but not set seed at all. I would leave them to die overwinter, and if there has not been enough frost by mid February say, cut them at base and compost all the tops, the roots will not regrow.
Phacelia is more persistent and you could do your option 1, and/or try cutting some too at ground level. I am unsure if phacelia may regrow, but it’s better for soil organisms if roots are left there to decompose.

[RhysParticipant]

Charles

I have used phacelia as a quick cover crop in early spring on border patches I will not plant with e.g. Sunflowers until May. I have never had much regrowth subsequently. You do get the odd plant, but I assumed it was previously non-germinated seeds.

[Jasper ShawParticipant]

Hi Charles, thanks for the quick reply. Yes I’m very much enjoying the use of the plot – this year has been more structural work than planting but should be able to make more use of the growing space for vegetables next year.

I shall follow your suggestion regarding the mustard – is good to know that it may not seed before winter but will keep a close eye on the frosts over winter. I’ll give it some further thought regarding the phacelia and perhaps try 2 different methods with the 2 borders to experiment whilst the opportunity is there.

And thank you Rhys for your point there too – interesting that regrowth in your experience has been pretty limited. Can I ask when you have grown phacelia as mentioned how did you deal with it when it was no longer required – i.e. did you cut it down and compost it before flowering?

[RhysParticipant]

Jasper

Yes, I harvested and composted, usually because you need 3-4 weeks to compost in situ and I usually do not have that time to spare. I usually give the bed a brief hoeing with a copper tool before replanting…..

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