Questions and answers

[charlesModerator]

Q from Judy, April

"Perhaps I can ask one of my questions now as our new greenhouse is almost ready for use – the builders are doing the final tidying up. We have a raised bed on two sides for tomatoes etc. Kevin (husband and head gardener!) wants to fill it with top-soil and compost. I’m suggesting newspaper at the bottom and then a mixture of multi- purpose, well-rotted manure and our own compost and possibly some grit?"

A from Charles

"Yes there is no need for soil, or grit, and paper may also be unnecessary if the depth is six inches or more, because that amount of organic matter is an effective mulch for all weeds – although any bindweed will eventually grow through and must continually be removed. Do firm the compost and manure with the back of a spade."

 

Q from Nick Barnard

"We want to grow salads and veg outside the office in London in some old bulk food bags, 500kg capacity and about 1.5′ deep. They are made of woven white plastic. What medium should we use and do they need gravel at the bottom for drainage?"

A from Charles

"Some scalpings/gravel (about 2") would be good if you are placing the bags on a non-draining medium such as concrete, although even then if the ground is sloping they are not necessary, just compost would be best. Green waste compost could be your main ingredient although I would hope to put some animal manure with it to add nutrients, it all depends what you can find in Wandsworth: I think the Royal Mews have some excellent spare compost."

 

 

Q from Susan Harley, April

"I need some more of your invaluable advice in creating my new veg haven. I have cleared a large patch of ground , covered it with good compost and well rotted manure and a plastic sheet. I want to create an Asparagus bed and  the new crowns arrived yesterday. Last night I read your book on the appropriate section and my concern is that some nettle and couch grass will still be present in the "new patch". You advise waiting until the bed is clean possibly until the end of summer. I am prepared to do that, but my question is what to do with the new crowns in the meantime. Should I put them in pots or on a clean piece of land and move them in the autumn ?.

I was also reading an article about companion planting and one suggestion was to plant tagetes marigolds in areas you want weed cleared as their roots go deep and crowd the "buggers"out. So I would welcome your thoughts on this subject."

A from Charles,

"You could pot up the crowns into any pot large enough to accept their full spread of roots (quite big pots though!), worth it for getting the soil clear of couch above all. Nettles do NOT grow from residual root pieces so a careful dig of their main crowns should see them gone. Be thorough with couch – and I tried the Tagetes once, it is a bit of a myth, sure they discourage couch grass, but not massively and not enough to really make a difference. Adding compost/manure is more effective as it makes the couch ‘redundant’ in the end, in the sense that couch roots are an anti-compaction healer for soil, among other things. You could then plant your potted crowns next spring, or in the autumn if soil is clean."

 

Q from Janet Halliwell, April

"Another question I do hope you can answer for me. Our daughter, Rachel, has been allocated an allotment which we went to see yesterday. The council have skimmed the top off & laid flags as paths down each side. She has been told by the council man that they prefer raised beds, and as the soil is poor he suggested putting down a weed suppressant membrane & buying in top soil. This horrified John & me, but Rachel said that, as she has asthma, she couldn’t use the no dig method because of the spores in the manure. As we were leaving, another plot holder was shifting his delivery of manure;  talk about black gold, it was amazing stuff. He said that he thought it was ten year old horse manure; it looked more like compost. Do you know if the spores become less active as it gets older ?  If that happens, is it then no longer any use to the soil?

The way we would like to go is to dig out the perennial weeds we can see which are docks. I did take my spade & the soil was hard to get into but I could see bindweed & horsetail. As the manure looked so good, could we put the 6" layer down & plant through it? I feel it would be hard to get into the soil so do you plant into the manure or into the soil?  Would the roots find it hard to get into the soil? We would make the raised beds before doing the planting."

A from Charles,

"Basically the answer is yes that I would dig out docks & then mulch with 6" of dark manure and plant into that, I did something similar last autumn with two year old manure. Spores do diminish, as you say the manure becomes more like soil and has rather less value after about three years or so; hopefully she will be alright with it. Keep pulling the bindweed & horsetail!"

 

Q from Emma Chambers, February

" Have just agreed a 3 year lease of a derelict walled garden I am sharing the total area with some friends so my plot will be 30m x 60m. Half of the plot is solid nettles and the other half is solid couch.  My friends are keen to arrange for a small tractor to plough and then harrow but I’m worried that this may not be best approach. If I did agree to get the area ploughed I was thinking of putting a third into veg for this year,  a third under black matting and a third green manure.  I just don’t know whether this is madness.

 Also where can I buy the large seed modules and do you recommend any particular compost supplier?"

A from Charles,

"The answer depends partly on how quickly you want to crop. Couch needs at least 6 months light-excluding mulch, or you could plant certain wide-spaced veg like winter squash through a mulch (also brussels/large brassicas, courgettes but not salad, leeks, carrots or beetroot).

The nettle area is easier & could be mown, then mulched for about 4 months, from now until early June, then grow almost anything. But I expect there is some couch among the nettles, so be careful of that & be prepared to trowel it out if needed. Couch can, most emphatically, be got rid of this way over a year or so. But it risks always spreading in from edges where it persists – so maybe mulch the path/edges of the garden right to the walls.

Alternatively you could agree to ploughing and then mulch. The area with nettles, if only nettles, will then be croppable from about April or May and can revert to no dig. I would aim to spread 3 or 4 inches of compost after the ploughing. Your one third crop idea is good, I would do the other two thirds black mulch.

Or if mulching from scratch, spread the same compost first before mulching. Re compost, check out green waste from your local dump, sieved to 15mm maximum, should cost around £20 ton delivered, you could use a full 14 or 16 ton load (around £300, good investment!), maybe after that find cheaper animal manure, or use some now as well with the green waste, keep the latter on top as it is weed free. For module compost, look up West Riding for multipurpose.

Re module trays, B&Q do plastic 60 cell trays @ £1 each. Maybe also 40 cell polystyrene – both sorts are reusable many times. Avoid flimsy trays.

Be prepared for it to look a little messy this year, your transition year, and more beautiful thereafter."

[paulineMember]

Hi Charles
I am very interested in your methods. I have just taken on a heavy-clay allotment infested with couch grass (and bindweed) so was very interested in your reply to Susan Harley. At the moment trying to kill it by covering with a tarp. Would be really grateful if you could please expand a bit on what you meant by
” compost makes couch redundant in the end, couch roots are an anti-compaction healer.” Sorry I am being slow here but cant quite get my head round this!

Many thanks

Pauline

[charlesModerator]

 Hi Pauline

Yes it may seem strange especially when couch can be such a fiendish weed to deal with. I have noticed in my heavy soil that couch is mostly in compacted soil around field margins, where tractors had pounded and squashed the soil more than in the middle of the field. So that suggests it develops where soil is lacking air. 

Then I have noticed that after six months to two years (depending on the infestation) of mulching with some compost and manure, with cardboard or any other light excluding material on top, the couch disappears and also is less inclined to spread in from the grassy edges where it had also been rampant. Which suggests to me that once soil is well structured (by compost-fed worms and other soil life) there is less need for couch roots to open up the soil and allow air to enter.

Sorry if that all sounds rather esoteric but my experience over the years leads me more and more to see patterns in weed growth that suggest a reason for their presence. Above all, leaving soil undisturbed is the most powerful way of avoiding too much weed growth. The opposite case is abundant chickweed after soil has been rotovated…

In your case, the tarpaulin will surely be weakening the couch and it will be more effective if you can spread some reasonably well rotted organic matter on the soil underneath it, thus encouraging more soil organisms to proliferate.

[urbansmallholderMember]

Hi Pauline,
The only thing I can possibly say about couch is if you’re pulling it by hand then please wear gloves, I have been speared and it does hurt. But it does feel good when you pull a whole piece out completely!!!

[Don WoolleyMember]

Is it possible that not digging encourages mares tail ?
I have not dug my allotment for many years now.In the last two years M.T. has caught up with me but seems to be leaving neighbouring ,dug plots, largely alone

[Author]

Posts