Slug Control

When we find damage in our yards and gardens that resembles the poor rhubarb on the right, careful eyes are very likely to discover that the slugs are out of control.  

Organic slug control begins with nurturing the soil.  Soil may seem like an odd place to start a discussion on slug control, but the easiest way to control slugs over the long term is to invite slug predators to do the job for you.  Slugs are at their most vulnerable to predation as eggs in the soil and as tiny hatchlings that live for months beneath the soil surface.  To permanently reduce slug populations we need to think about our garden soil as a living and complex ecosystem.

 

E.O. Wilson, in the Nova DVD, Lord of the Ants,  waxes poetic about the soil beneath our feet.  He mentions that most people think of the surface they walk on as two dimensional.  However, he goes on to explain that soil is one of the most complex and most diverse environments on the planet.  In most natural undisturbed ecosystems this is still absolutely true.  But it may not be true in your garden, which Wilson was not considering.  

The soils were we garden have often been compacted, leveled, and groomed to death.  In addition, our gardening habits may work against the soil ecosystem.   Baring the soil to the sun causes oxidation of humus and death to most soil organisms.  Further, chemical fertilizers are toxic to most soil organisms and beneficial insects, and if your soil has ever been treated with pesticides or herbicides the soil environment has been further compromised, or possibly completely massacred. 

We can, however, turn the soil around.  This is important to slug control.  A complex living soil environment will nurture and protect the beneficial predatory insects which will happily devour slug eggs and young slugs.  By improving the soil environment, we also improve the productivity of our gardens.  That’s a double win, more productivity and less damage!

In building and nurturing living soil, we may find we need to expand our ideas of what appropriate soil care is, what we might want to dig in and bury, as well as what we think is appropriate to use as mulch.  To encourage a diverse soil environment, a diversity of organic matter needs to be incorporated into the soil.  This feeds and creates habitat for a self supporting web of life, which will help keep pests in balance and protect our gardens.

This photo is from a hole I dug in a bed in my Hoopa garden, to remove mature parsnips, garlic, potatoes, and giant snow drop bulbs.  It was about 12 inches deep, possibly a little more.  I didn’t work the soil after digging.  That's just what the bottom of the hole looked like.  And, by the way, I didn’t need a shovel, I just used my hands.  The important things to note are that there are different types and different sizes of organic matter present.  And the soil, even though it is moist, is a loose assortment of various sized crumbs.  This is your goal!  Soil that is crumbly, full of air spaces and organic matter of different types and sizes is exactly what plant roots need, exactly what the soil nutrient cycle needs, and exactly what the predatory insects that dine on slug eggs and slug hatchlings need as well.

You can achieve soil like this, easily, and without spending any money.  Everything you need is probably already produced in your garden and kitchen!   This technique is a variation on an old fashioned and little known British technique.  It is variously called garbage gardening or trash gardening, and it utilizes all kinds of organic matter.  In this technique, the garden row is prepared by trenching,  the trench is then filled with organic matter including kitchen waste, weeds, and other garden debris,  which is them buried under at least six inches of soil, and the resulting mini berm is then planted.  My modified version has been named “The Compost Hole Method” by my friends, and just uses planting holes instead of trenches.  Some of my friends have further adapted the technique to their gardens, environments, and resources.  At the community garden where I am now the coordinator, we have re-adapted the technique once again; using wide trenches and probably a full ton of weeds buried under eight inches of soil.  The two photos below show two different groups of tomato plants grown in the same garden, one over the trenched and buried weeds, and the other of tomatoes that were planted in our soil in an area that was tilled, top dressed, and then had finished compost worked into the planting holes.  The tomatoes on the left were grown over the buried weeds, the ones on the right by more traditional organic methods. The difference is amazing!

Burying your compostables including weeds, garden debris, and kitchen waste pays dividends, the very first season!

"Soil both craves life and wants to produce more life, even a hundred fold."  Fred Bahson, Soil and Sacrament, page 3.

Before we get going on the Compost Hole Method, which you can modify back as a method to prepare whole rows or to prepare wide beds, I want to share a little secret with you.  Amongst all the other organic matter you will utilize in building your living soil environment, you will want to include short sections of sticks and stalks. They are the secret ingredient for super powering organic slug control in your garden.  

Many of our garden plants produce strong stalks when we allow them to flower and begin the process of setting seed.  Clip the excess stalks into sections from about 2 – 4 inches long.  These carbon rich sticks provide plenty of surface area for beneficial bacteria, protozoa, mycelium, and other beneficial soil organisms to colonize, and the green plant matter that forms the skin and pith of the sticks (as well as the other organic matter you will be burying) provide the beneficial microorganisms with food.  As the sticks and stalks are colonized and broken down, they often become hollow.  

The combination of this hollow structure and the presence of beneficial organisms creates the perfect home and food source for the tiny soil living creatures that devour slug eggs and young slugs before they emerge from the soil.  These predators will arrive in your garden as eggs laid by their mothers.  They do not come out of their eggs big enough to slay slug eggs.  They need other smaller organisms to devour while they grow.  The hollow sticks, in addition to offering them an excellent food source, also provide them with shelter from larger predatory soil creatures.  Your soil is definitely going to be a jungle of tiny creatures.  But that’s the way it should be, and it will make your work so much easier!

In the post on Slimy Slugs, I mention creating a coarse mulch of clipped sticks.  This mulch of clipped sticks is important to mature slug predators, but now you also know how important it is to include some of these sticks in the soil itself.  An abundant garden will produce enough of this material to provide for both needs, however, it may take a few years of soil building to get to the point that you have enough sticks in production to do both.  If you don’t have a source of fresh sticks and stalks to clip, check out the straw offered for mulching and bedding at your local feed store.  Most straw is actually the leftover stalks from a variety of grain crops.  Look close at a bale, and you should see that it contains hollow tubular stems.  While these stems will decompose faster than most garden stalks will, they will serve you very well until you get an ample production of stalks from your own garden.    

Check the straw out before buying, to make sure it has fairly sturdy hollow stems.  You don’t want hay.  Hay decomposes too quickly, it has very few hollow stalks, and it is full of grain and weed seed that will sprout in your garden.  Be sure to clearly ask for straw and check it out before you purchase it.  Yes, yes, I know I did say that you could do this without spending money, and you can.  It will just take a little longer if you don’t now have fresh sticks and stalks to clip.  The fresh sticks and stalks are actually superior to straw, because they still have lots of juicy plant material that will feed beneficial microorganisms, and those microorganisms will be right inside the hollow tubes where the baby slug predators can eat them while they take shelter and grow.  Sticks and stalks are better.  Straw will help if you don’t have them.  If you don’t have money for straw, just plant extra of whatever you are growing, and let it bolt and flower—your garden can easily produce plenty of stalks in a season or two.  (Weed stalks work too!)

A couple of other sources of hollow sticks you might already have around your yard are butterfly bush and elderberry shrubs.  They both attract pollinators and beneficial insects, and elderberry has the additional benefit of producing berries that are edible and medicinal.  Once well established, both of these shrubs can withstand being cut back severely, and will generally regrow vigorously.  Once you’ve clipped your sticks, you might want to allow them to dry before burying them and using them or using them as a coarse mulch.  Sometimes those short clippings will sprout and root if you utilize them fresh.  That has never happened in my gardens, but I know of other gardens where it has happened.  Another alternative is to take your chances, and then pot any up that start to grow and share them with your gardening friends.  Fresh sticks are better than dried, but dried are better than none at all.  Meanwhile, you may have other plants that produce hollow stems, twigs, or sticks in your garden.  Give them your love, they deserve it!

Ok, let’s quit talking and get to work!  The first thing to do is build soil. We’ll start with The Compost Hole Method, and build some really fabulous living soil. Once your soil will provided a comfy nursery and larder for your slug eating predators, you will want to  attract their parents to your garden.  All you need to know is covered in the post on Slimy Slugs.

You are also going to want some help cleaning up the slugs the beneficial insects miss before they emerge from the soil.  Those mature slugs are the ones we hate the most after all.  Unless you live in the desert, toads and other amphibians are probably your best bet.  You will find lots of information here on creating amphibian habitat in your garden:  http://harvestsgardeningsecrets.blogspot.com/2010/11/hedging-for-amphibians.html 

If on the other hand, you live in a warm dry environment, you will want to create habitat for lizards and snakes.  Piles of rocks and downed wood, that have lots of protected and hidden spaces for hibernation, egg laying, and escape from predators are the ticket.  If you have a large garden, you will want to include this sort of reptile habitat in strategically located spots around your yard or garden.  Snakes prefer to enter their lair at the ground level.  Lizards generally like an elevated look out, say two to two and a half feet about ground level, with safe hidey holes directly below their look out. And since snakes will eat lizards, you might want to choose which creatures you want to attract to your garden and design with them in mind. In addition, all reptiles prefer their dens to be located in the sun, and to have flat areas for basking.   Think in terms of creating garden art as you create their habitat.  It doesn’t have to be a messy pile of unsightly rocks and downed wood.  It can totally be attractive, and it can include the odd whimsical element to make it fun for other sorts of garden visitors as well.

Speaking of other garden visitors, many species of birds also have a reputation for eating slugs.  While I have not ever personally found them particularly helpful in this regard, they do provide a wide range of pest reduction services.  Attracting birds for the purpose of getting them to eat pests is a little different than simply attracting them to feeders.  Learn more here: http://harvestsgardeningsecrets.blogspot.com/2012/01/mystery-in-garden.html

It is going to take a little time to get your garden environment productive and diverse enough to keep the slugs from over populating.  In the meantime I suspect you will be hand picking, just like me.  I am gardening in a new location and still have lots of work and planning to do!  I use a plastic bag as a glove when hand hunting slugs, and I stash them in a jar with a tight lid. While I forgot to leave any head room in the half gallon jar pictured below (don’t forget!),  I filled it with slugs in about a half hour.  Ugh!  Left in the sun for the day, the slugs were dead the next morning.  I promptly buried them for their nitrogen boost to the soil and to garden plants.  When you do this, don’t let them age in the jar, they create a terrible stink; but when buried the soil forms a filter and the microorganisms make quick work of the rest, there’s no smell at all once they are buried.  (Quick tip, dig your hole before you open the jar!)   

Beware!  Slugs can carry disease.  Before you try this, contact your health department or cooperative agricultural extension and ask if slug borne meningitis is a problem in your area.  If it is, just get yourself a couple of plastic bags that have no holes, use one as a glove to collect the slugs, and the other as a receptacle.  When you’re done, knot the bag closed with the slugs inside, and stash it and the ‘glove’ in the trash.  And be sure to wash your hands!  Slug slime is gross!  Oh, but slug slim is actually good for the soil.  It helps the soil form that very desirable crumb texture and the beneficial soil microorganisms love it.  Slugs are not all bad.  But an over population of slugs is terrible. 

We are beginning to learn to think of the garden as an ecosystem, where all things exist in balance.  The role of the gardener is to steward that balance and in return to be deeply nourished . . .

Questions?  Additional organic slug control tips?  Please leave a comment!

~~~

Text and photos copyright Harvest McCampbell, 2015.  Updated 11.20.2016 with a quote and minor edits.   Please feel free to use the buttons below to e-mail, re-blog, tweet, share, or pin this post.  All other rights reserved.

Compost Hole Method, Part 2

Please see Compost Hole Method, Part 1.

Step 6, on your right: Sweep your floor, or gather fall leaves or twigs, or tear up junk mail. Animal hair (as shown) or even human hair is a great addition. It tends to discourage rodents, it adds slow release nitrogen, and it helps keep the soil from compacting--which allows it to breathe and provides plenty of habitat for soil microorganisms to colonize.





Step 7: Layer dry organic matter into the top of your hole, alternating with crumbled soil. Here we see pet hair, which is a nice slow release source of nitrogen.












Step 7, continued, on the right: Fallen leaves and twigs also make good materials to layer with soil as you fill the hole. They will prevent compaction, provide pathways for roots, and food and habitat for micro-organisms. As they break down they also provide nutrients for your plants.







Step 7 continued, on the left: Layer in dry organic matter . . . here it is a torn up cellulose egg carton . . . Which will have the same effect as dry leaves. Junk mail, newspaper, cardboard, really any dry organic matter you have handy will work.










Step 8, on the right: Top off with a layer of crumbled dirt.


















Step 9, on the left: Smooth the surface.














Step 10, on the right, optional: Build a mini berm to keep the seeds from washing or blowing away. The same effect can be accomplished by leaving the the hole slightly depressed, however as the organic matter decomposes the soil level will subside leaving a nice watering basin at the base of your plants.



Continued in Part 3.




All text and photos Copyrighted, 2011, Harvest McCampbell

The Compost Hole Method, Part 1

This post explores a variation of the technique originally described in this blog way back in 2006, "A Simple Garden Routine - useful for bad backs, no time, short budgets." The primary difference being that the photos show using the method with seeds planted in place, rather than starting with seedlings started inside. This little technique has come to be called "the compost hole method" by my friends, for lack of a better term.

Before we get down to the compost, I thought I would share some photos of a garden grown with this technique. Every plant you see in this picture, started out over or next to a compost hole--including the trees.

All the photos are from my garden in Hoopa, CA, where I lived for over a decade. The photo to the left is a detail from the border pictured above. At the bottom of the photos is a cross between red Russian Kale and an ornamental cabbage. At the top is ruby red chard. Both beautiful, both edible.










On the right is another detail from the same border, pictured is another crossed kale, as well as some parsnips, and violas.














On the left is another detail from the same border. Pictured is giant red Japanese mustard. All these pictures were taken on 5.17.08. Now we can move on to the compost method these plants where grown by.








Below, you see the first step in creating an incredibly productive and diverse garden. Choose a spot and dig a hole. You want your hole to be at least 12 inches deep, and no more than 18 inches. This keeps your compostables in the biologically active zone, so they will properly decompose and not leach nutrients into the ground water.


















Below is step two, add between a quart and two quarts of compostables to your hole. Don't compact them, as the air spaces are important for providing oxygen and habitat for the nutrient cycling soil organisms.

Next, comes step three, below. You can add the grass or weeds that your removed when you started digging your hole. Just bury them deep enough that they can't grow, either at the bottom of the hole, or upside down right over the compost. Many beneficial organisms will be in the soil around the roots of the grass and weeds. They will help cycle the nutrients in the buried organic matter.



















Step four: crumble a shallow layer of dirt loosely over the compostables, weeds, and grass. (Below)
























Step five, below: sweep your floor, gather fall leaves or twigs, tear up junk mail. Animal hair for instance, or even human hair is a great addition. It tends to discourage rodents, it adds slow release nitrogen, and it helps keep the soil from compacting--which allows it to breathe and provides plenty of habitat for soil microorganisms to colonize.

















Continued at the link:
http://harvestsgardeningsecrets.blogspot.com/2011/02/compost-hole-method-part-2.html

All text and photos Copyrighted, 2011, Harvest McCampbell

Let Worms do Your Work!

The lowly earthworm is really a knight in shinning armor when it comes to garden soil. They tirelessly work to improve water retention and drainage, decrease run off and erosion, aerate the soil, and improve tilth and structure. They also increase nitrogen and the bio-availability of other plant nutrients. They do all this for free and with very little help. All they ask is a safe place to live and plenty of organic matter. You can encourage worms in your garden and let them work for you. Here’s how:


Throw away your rotor-tiller:

I know this might sound sacrilegious to many gardeners, but tillers kill worms. And worms turn soil. While you are out there tilling that soil – risking injury, straining your back, and burning up expensive fossil fuel, you are killing the very creatures that will do the work for you, for free. Tilling soil encourages erosion, topsoil loss through oxidation; and the formation of hard pans. While you are loosening the top layers of the soil by tilling, you are also compacting the subsoil. Repeated tilling on the same plots eventually causes the subsoil to become impervious to water and roots. Worms on the other hand will gradually loosen and aerate all levels of the soil, recycling nutrients that have leached into the subsoil back into plants active root zones.

OK, you ask, if I can’t use my tiller, what do I do? There are many options available to home gardeners. These methods generally involve mulching with plenty of organic matter, or building raised beds. “No Till Gardening” was first made famous in 1959 by Ruth Stout in her book How to Have a Green Thumb Without an Aching Back. Fortunately for us, there is a new edition: Gardening Without Work: For the Aging, the Busy, and the Indolent, published by Lyon Press (1998). A more scientific look at no till gardening can be found in Weedless Gardening, by Lee Reich, published by Workman Publishing (2001).

Feed the Worms:

Worms like organic matter, and plenty of it. They are living creatures; they need to eat. They don’t actually live on dirt, however they do ingest plenty of common garden soil. That soil is used as grit in their digestive process, which also involves beneficial bacteria. (These bacteria fix nitrogen, improving your soil for free!) What fuels a worms metabolism is the organic matter that we burry, mix in to the soil, or use for mulch. As that organic matter begins to decompose worms work their magic.

Worms prefer freshly decomposing organic matter. That organic matter gets mixed with the grit from garden soil, beneficial bacteria, and, well, worm slime inside the worm’s gut. The worm extracts its energy and nutrition and out the other end comes what is referred to as “worm castings.” Lots of research has been done on this substance. Worm castings are high in nitrogen and nitrogen fixing bacteria, which continue to improve the soil after they have been cast. Their digestive process reduces or eliminates harmful bacteria and soil born disease organisms. The castings are also a unique chemically bound composition of mineral soil, worm slime, and organic matter. They have very beneficial effects on plant health and nutrition.

Worms deposit their castings through out the soil and at the soil surface as they go about their business tunneling and searching for food. I find that by the end of summer, any organic matter that I buried in spring has become pure worm castings. When I make my fall planting holes I use those worm castings to top dress my garden. Then I burry more organic matter for the hungry worms and plant broccoli or kale for my own dinner. Fall buried organic matter is usually not completely devoured until the following fall, but the spot can be used in summer by tucking in your plants and providing them with plenty of mulch.

"There is an entire ecosystem in a handful of soil: bacteria, fungi, protozoa, nematodes, earthworms.  Through their breeding and dying such creatures vivify the world."   Fred Bahnson, Soil and Sacrament.

Worms, worms, where are the worms?

If you don’t find several worms when sifting through a shovel full of your garden soil, you may want to purchase some to supplement those that may be hiding. The red wigglers and night crawlers available for use as fishing bait make a dynamic garden duo.

Red wigglers work the top few inches of soil, and will happily consume manure, decomposing mulch, and other organic tidbits. When temperatures turn hot, they will burrow deeper into the ground. If you have buried organic matter down where the soil stays cool, they will thrive through the summer months.

Night crawlers, when well fed, can grow to tremendous proportions. They form semi-permanent burrows and feed at the surface and on buried organic matter. They will also pull grass cuttings used as mulch down into their burrows adding more organic matter to your soil.

Between the two squiggly creatures your soil will be thoroughly cared for. Just make sure you have a shady spot with good drainage and plenty of organic matter before you hire them on. They will multiply and spread through out your garden with very little effort on your part.


More Benefits:

Besides saving your back, and improving plant nutrition, worms benefit the soil in many ways. The very slime that glues the organic matter to the mineral soil in worm castings prevents erosion and top soil loss. This glue reduces the ability of the soil to dissolve in water and get washed away by normal irrigation. The granular nature of the castings reduces the soils tendency to turn to dust and get blown away. The physical structure of the castings also benefits plant roots. Worm castings resist compaction (unless you work at it). The spaces between the castings provide room for air and moisture in the soil. And the loose structure of the castings are easily colonized by plant roots.

Worms are wonderful. They improve the soil both nutritionally and structurally. If we let them, they reduce the work of gardening immensely. They are out there right now, waiting to go to work for you.
More info:

For more information see the following articles from my blog:
A Simple Garden Routine - useful for bad backs, no time, short budgets – this article tells in detail exactly how to garden for and with the worms.

If you missed the article on organic matter, Nurture Your Soil for Free, you can read it here: http://harvestsgardeningsecrets.blogspot.com/2006/05/nurture-your-soil-for-free.html

You can also use the search function in the upper left corner of this blog to find more information on worms, soil, and organic matter: http://harvestsgardeningsecrets.blogspot.com/

For the low down on the research related to worms and gardens check out this site:
http://mypeoplepc.com/members/arbra/bbb/id19.html




Copyright 2006 Harvest McCampbell, from my column "Digging the Dirt," published in The Hoopa Valley People Newspaper, June 20, 2006. Posted here with permission.


Updated with a book quote and minor editing on 11/17.16.  Text and photo copyright Harvest McCampbell.  Please feel free to use the buttons below to share.  All other rights reserved.