The Pros and Cons of Mulching

, written by Jeremy Dore gb flag

Garlic with a sawdust mulch

Mulching is the practice of covering the soil around the vegetables and plants you want to grow.  This is done to boost the various natural processes that help growth and to suppress weeds.  It’s something that nearly all organic textbooks recommend and is amazingly easy to incorporate into any garden system.  So why do more of us not mulch around our plants?

Mulching can be done in several ways: organic matter (such as woodchip, straw or leafmould) can be placed around plants and will eventually rot down into the soil improving its structure.  Alternatively, sheet mulches (such as cardboard or permeable black plastic) can be used or even more permanent materials (such as slate, stones or gravel), although the latter are only usually used for low-maintenance ornamental areas.

Strawberries mulched with straw

The benefits are:

  • Mulches suppress weed growth
  • Mulches retain moisture - particularly helpful in hot summers
  • Mulches reduce soil erosion – useful during winters and heavy rain
  • Mulches can insulate crops from extreme temperatures – especially useful for early and late crops
  • Organic mulches can rot down to provide soil nutrients and encourage beneficial soil organisms and worm activity
  • Mulches can be used to prevent some crops rotting (such as strawberries) by lifting them off the ground

There are some things to be aware of too:

  • Mulches can be homes to pests, although combining with other good organic practices should minimise this
  • Organic mulches usually need to be applied in a loose or partially-rotted state or the first stages of decomposition, otherwise they can lead to nitrogen being taken from the soil, or anaerobic decomposition which can lead to ‘sour mulch’ which turns acidic and damages the plants it is supposed to be protecting. 
  • Organic mulches usually need to be quite thick - generally a good 1 to 3 inches thick placed around plants; more if the mulch will rot down to something smaller.
Sweetcorn mulched with poached egg plant

I’ve been growing poached egg plant (Limnanthes douglasii) in huge quantities this year.  Apart from having wonderful flowers that attract bees and other beneficial insects, it makes an excellent ‘green manure’ to dig into poor quality sandy soil.  After clearing one area I was just about to dig it into the ground when a gardening friend suggested I use it as a mulch around my sweetcorn.  So, I now have most of my sweetcorn duly mulched, with a few left without to compare with (I always like to run little ‘experiments’ like this in my garden to learn from). 

I have also been growing the wonder-plant comfrey next to my compost bin, which has leaves rich in nitrogen, phosphates and potash.  Once harvested and dried, these will be used for mulching around hungry fruiting plants such as tomatoes and peppers to suppress the weeds and feed the soil.  And finally, I have a big bin of rotting leaves turning into leaf-mould which makes an excellent cover around plants – not rich in nutrients but very good for soil structure and weed suppression.

My big problem with mulches is generating enough organic material to do it well.  It’s like compost – fantastic in theory but you never seem to have enough to go round.  I’d love to hear what you do to generate good mulches and what successes you’ve had, so please do add a comment below.

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Comments

 
"I'm all for anything that keep the weeding down to a minimum, can the poched egg plant be grown amoung on under taller veg to be a living mulch? I'v been told that some green manure plants can be used as ompanion planting to keep weeds down is this true?"
maggie on Friday 6 June 2008
"Maggie, I would be hesitant about using it as a living mulch: Although it can provide quite a thick coverage it may not be adequate to completely deter weeds and I would be concerned about competition with the taller vegetables (for moisture and nutrients). However, I do garden on a sandy-based soil which easily loses both of these, so it may do well on a richer, heavier soil. If you try it then please do post the results here - definitely worth experimenting with it on a few plants with others using a different mulch to compare with."
Jeremy Dore on Saturday 7 June 2008
"jeremy, thank you for your thoughts on my dilema, I will as you suggested try this on a small part for as experiment. and will let you know on the outcome. maggie"
maggie on Monday 9 June 2008
"jeremy what kind of ethnic origen is the name dore? "
jeremy samsel on Thursday 2 April 2009
"Hi, just wondering, did I do a bad thing today when I mulched my vegetable garden with dyed black shredded mulch? Thanks, Bruce"
Bruce on Sunday 5 July 2009
"Bruce, it all depends on what the dyed black shredded mulch contains - is it a vegetable based dye (in which case it will probably be fine) or does it contain synthetic materials or chemical dyes that could leak out(in which case I would remove it). Finding out can sometimes be hard which is why many people recommend just using natural materials from your own garden as mulch."
Jeremy Dore on Monday 6 July 2009
"I was thinking of using straw to mulch around the strawberries in my inherited strawberry beds, to replace the rather rotten black plastic that I have just removed. Is it best to use brand new straw? I considered the used straw from my winter chicken shed, but think it will be too 'hot'."
Lisa on Tuesday 23 March 2010
"Hi Lisa, I don't know the answer to your question but, like you, I would be hesitant about applying chicken manured straw to strawberries. They do like Nitrogen but chicken manure usually has to be composted and well dug into the soil to prevent problems. Maybe try it on a small sample this year and let us know the results."
Jeremy Dore on Tuesday 23 March 2010
"Thanks Jeremy. Good idea to just use it on a sample batch! I'll update later ..."
Lisa on Wednesday 24 March 2010
"I used the incredible amount of scarified moss from our lawn last year - it makes a cosy, mouldable collar around and under all plants. "
A.Taylor on Monday 19 April 2010
"I've heard of people using grass clippings for mulch and I was just wondering what your thoughts were on this. Can you use freshly cut grass or should you wait a few days before mulching the garden. We do not use any sort of lawn fertilizers or treatment so I am not worried about chemicals from the lawn. Thanks."
Bethany on Tuesday 27 April 2010
"Hi Bethany, I think it's best to allow the grass cuttings to dry out a little first, especially if the plants are young. However, it's not something I have tried both ways so I would welcome other people's views on this."
Jeremy Dore on Friday 30 April 2010
"In my area, the south of England, we can buy truck loads of dried bracken from The Forestry Commission. This is a good mulch and soil improver but not a great compost. So the limited amount of compost that we do produce goes on the vegetable patch as it is not needed as mulch elsewhere."
Mary Palmer on Saturday 3 July 2010
"I, too, would like to use straw as mulch for my raised beds. I am growing all the staples; tomatoes, cukes, squash, peppers, eggplant, etc. Is it ok to use it as a mulch around all these plants? I really want to keep the grass down. My garden is a section of what used to be yard, so the grass keeps coming back."
Nick Manley on Wednesday 18 May 2011
"Nick, straw will work well but it doesn't add as much nutrient value to the plants as other mulches. The one thing I would caution you about is that slugs and snails love to hide in straw - last year I had large numbers of slugs hide in the straw mulch I used around my strawberries. I'm not sure but I think this is more of a problem with straw because it doesn't rot down as quickly as other mulches so it leaves more room for the slugs etc."
Jeremy Dore on Wednesday 18 May 2011
"I am very confused about what is a good mulch to use for an organic vegetable garden and, besides straw, I am not seeing any clear suggestions in the blogs. What about bagged cypress mulch or other mulches found in garden stores? I don't have a lot of other options besides mulching paper or newspaper. Is newspaper (with ink) OK for mulching around plants like tomatoes, peppers, etc.?"
Cheryl Koenig on Sunday 29 May 2011
"I have only just really got into mulching while growing veggies this year. I use to dig my plant residue and grass clippings in during the summer break to put some fiber back into my soil. This year I have been making a mulch/compost and adding it when one crop has finished before planting another crop. I now have it down to leaves and grass clippings for dry matter and then adding used coffee grindings, food scraps and green plant residue to speed the composing up. Add water and turn it over each week. After about a month it is half composted. I now have 2 neighbors supplying me with lawn clippings. During my summer break (too hot to grow things) I intend to do this process on the fallow garden. Will do about 4-5 piles along the garden and then dig it in when half composted. Also by using this product I hope to be able to prolong my planting in the spring and also start planting in the autumn earlier - along with using some shade cloth hoops. My garden is nearly full of crops - usually I have harvested them all by now. "
Mike on Thursday 30 November 2017
"I have been adding cartloads of semi-composted wood chips ( mechanically chipped logging debris) to our garden for three years now, probably 40-45 cubic metres. In one bed of our vegetable garden, I put half a foot of dead leaves topped with half a foot (or more) of this chip material. Then I planted directly into that. Many of the plants, which included garlic, squash, beets and chard, were not even rooted in the underlying soil, just the mulch. This area of our large French potager (vegetable garden) was the richest, densest, with no watering needed but still the best harvest. I found no problem of pests there and no issue of nitrogen depletion as the chips continued to compost. But then, I water with diluted urine every two weeks or so, which may have helped. I highly recommend using this material as mulch, as deep as you can make it. A year later, the soil in that bed is far lighter and carbon rich compared to all surrounding ones. "
Earthdave on Wednesday 1 May 2019

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