Mulch magic?

I don’t often get requests, but last week my friend Perkin asked me to write about mulch. Perkin has acquired a pile of organic gardening magazines and has been struck by the number of references to mulch and the claims for its apparent magical properties. So, he got hold of some straw and mulched under his squashes. And, guess what? He created a fantastic habitat for slugs! He, therefore, asked me for my thoughts on mulch.

Mulching can work really well in some circumstances

Mulching can work really well in some circumstances

I too was seduced by the charms of mulching when I first read about it many years ago. My first experience of it was a wild success. I moved into a semi-derelict cottage around the time I got my first job. I had to hack my way through the vegetation to get down the drive and to the front door, so you can imagine the state of the garden. Anyway, I had read that squashes love growing in rotted vegetation, so the first spring I was there, I covered an area of rough grass measuring about 4x4m with black polythene, anchoring it round the edges by simply pushing it into the soil with a spade. I grew courgettes and patty pan squashes from seed in pots on my window sills (it may have been falling down, but the house had really deep window sills because of the two-foot thick walls). When It came time to plant out, the vegetation under the plastic had rotted down, the soil had warmed up and that summer I harvested a bumper crop.

When I moved house a few years later, I tried the same approach (although the garden was not so wild) and the results were nowhere near as spectacular. Over subsequent years I have experimented with various types of mulch – carpet, permeable membranes, grass clippings, cardboard, gravel, cocoa shell – but have never had the same success as that first time. There have been two main problems –  first, like Perkin, the issue of providing ideal conditions for slugs and, second, the mulch not actually suppressing plant growth (e.g. the permeable membrane which seems to let light through as well as moisture).

Sometimes, I have worked the slug problem to my advantage. The first year we kept hens, I mulched two raised beds with cardboard over the winter. By the spring, there were only a few spindly plants surviving in gaps around the edge of the mulch, but turning the soggy cardboard over revealed dozens of slugs. At this point I drafted in the chickens. They ate the slugs, consumed the weeds (mainly creeping buttercup), shredded the card, cultivated the surface of the soil and added some of their own special fertilizer: great job, girls! In fact, our garden has a smaller slug population now as a result of the presence of hens, but I still don’t want to provide them with perfect conditions to thrive.

Squashes of all varieties are flourishing in the 'four sisters' bed

Those big squash leaves prevent the growth of all but the most determined weeds!

The second problem can be avoided by selecting the right mulch – don’t use something that will blow away if you live in a windy place; don’t bother with permeable membrane unless it’s just one component of a layered system and so on. Chose a mulch that will deliver what you want – weed suppression, increased fertility, surface stabilisation, warming the ground, or any combination of these. Sometimes it’s better to incorporate organic matter into the soil than to apply it to the surface, sometimes a weed suppressant isn’t necessary if you plant a crop with big leaves or a ‘green manure’… think carefully before indiscriminate application of a mulch!

My experience is that mulches have their place, but they do not represent a magic solution and they are certainly not suitable for all conditions. As with so many suggestions, it’s a case of using mulch thoughtfully, knowing your specific circumstances and doing some careful experimentation to find out what works for you on your patch.

I’d be very interested to hear other people’s experiences with mulch, so over to you…

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10 Comments

  1. Gary Finch

     /  October 8, 2013

    similar problems regarding the slugs – mulching is fine for perennials or on a newly dug bed that has been cleared of pests – it’s usually the 2nd and future seasons that get the problems (i have managed to lose 8 meters of jerusalem artichokes to slugs because of continual mulching with the stems)- solution is to keep beds covered whilst bringing plants on in modules and pots etc and removing cover (and any moluscs hiding under it) and planting closely so that plants effectively much them selves (ala jeavons and ‘bio-intensive method) – skinny plants like garlic and leeks need interplanting approach

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  2. Planting closely and companion planting are perhaps the best alternatives. Squashes are good ‘self-mulchers,’ i found i don’t have to weed much when doing the three sisters style planting as the squashes act as suppressant.

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  3. I know nothing about mulch but this very morning, I purchased some trees to go in my front yard and the lady said “be sure and mulch well” . Then I saw your blog post. Serendipity!

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  4. Deano

     /  October 9, 2013

    I very rarely use mulch any more. I incorporate compost into the soil when a crop is harvested, and then where possible I plant my next crop. If no crop is going in I sow a green manure, and if it’s too late for a green manure I add more compost as a top layer (mulch), which is then incorporated in the spring before sowing.
    Not having mulch means that I can use a hoe for weeding.
    Close spacing of plants works well with sufficient rainfall, or irrigation, as long as you’re able to keep harvesting/thinning.

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  5. Sharon

     /  October 10, 2013

    I too tried straw quite enthusiastically this year, only to find that it was better for slugs than for cucurbits, so there were no cucumbers or squash this year 😦 I think I will stick with my close planting / interplanting.

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  6. After not really bother with mulching before I thought I would give it a go in time for this summer. I have spent the last month or so mulching our garden beds with pea straw mulch (fine straw, finely chopped and shredded) and have been really surprised with how well it retains the moisture in the soil and suppresses weeds.

    It is so fine that when you put it down it seems as though it will blow away, but a quick hosing mats it all together and the soil below stays damp even when the mulch is dried out. As you know keeping gardens sufficiently damp over summer down here is quite a feat, so this mulch can only be a positive thing. I haven’t noticed the slimy garden residents being more partial to it than the plain soil before either.

    An added bonus I have discovered when planting seeds is that all I need to do is to make a hole through the mulch with my dibbler and disturb the soil slightly below then drop a seed in. They seem to grow very happily like that and I have had more grow than I would have had I planted them in the soil normally.

    I imagine that plastic sheeting as mulch would be a disaster here, I have a small piece of tarpaulin that is on a corner of the driveway at the moment as a snail/slug trap, it is working so well that some lizards have moved in for the free feed! 🙂

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