WORDS: Simon Hart

Give The Worms Some Credit

We all want to use items that increase our garden’s fertility in the hopes of explosive yields. With that as our aim, there is one item that stands out as a must-have for all soil and soil-less gardens: worm castings. Vermicomposting is the use of worms to break down organic material. Worm castings are the result of their digestion process. This process will give you some of the highest quality castings available and help you create a more technical and successful garden experience without a lot of effort.

Current research show extremely complex benefits from the use of worm castings in agriculture. A green technology, vermicomposting is the epitome of reduce, reuse, and recycle. Research continues and our knowledge of these unsuspecting creatures in the soil shows a fascinating connection between the worms and overall ecosystem health. Their effects on soil biology, nutrient availability, and the complexity of their decomposition of organic materials are just some of the things being studied. Although we are just starting to understand the relationship between earthworms and healthy soils, worms have been fascinating people for millennia.

Cleopatra, queen of the Nile, decreed that worms were sacred and were not to be harmed. The Greek philosopher Aristotle declared them to be the guts of the soil. The great biologist, Charles Darwin, who may be best known for his theory of evolution, started his scientific work looking at earthworms. In fact, he spent the latter part of his scientific career looking at nothing but earthworms at Down House, his country estate just outside of London. He was fascinated by them and utterly convinced that worms were among the unsung heroes within the natural world; in 1881 he published his life-long research on earthworms. In one project detailed in his work, he took small coal stones, spread them over a field, and left them for 20 years. He then dug a trench to see how far down the worms had moved the coal. Talk about long-term research.

WORM WISDOM
Worm castings are an amazing soil amendment, but go easy on them! They typically contain 5 times the normal levels of nitrogen found in regular soils, 7 times more phosphorus, and 11 times more potassium! Worm castings also contain calcium, magnesium and other micro-nutrients as well as tons of beneficial organisms and microbes that help to restore soil life and begin recreating the soil food web. Worm castings rule!!

The Knowledge

The industrious nature of worms is a power that can be unleashed on all unsuspecting gardens. While all urban gardeners are familiar with worm castings, most buy their castings at their local shop because it is very convenient. But given just a little space, time, and knowledge it is possible to grow your own castings. Not convinced that it’s worth the effort? Have a look at the benefits and then the actual work involved in growing worms and supplying your own rich, microbial super-charged soil amendment.

Research shows that vermicompost stimulates plant growth even when plants are already receiving optimal nutrition. Improved seed germination, accelerated growth and development, and increased productivity and yield are all scientifically validated claims. There are new theories, such as the possibility of transient plant growth regulators being absorbed by the humates which form in rich worm castings. Other benefits, such as disease prevention and the ability to repel pests, are possibilities, but there needs to be more study to understand the mechanisms behind these potential benefits.

When compared to regular compost, vermicompost stands out as the winner. Higher levels of plant-available nitrogen, phosphorus, potassium, sulphur and magnesium make vermicompost nutritionally superior. Microbiology is also more complex in vermicompost than standard compost. Why? First, vermicompost is processed at a moderate temperature range that never comes close to the140 degrees Fahrenheit (60 degrees Celsius) or higher achieved in thermophylic digested compost. This means that your worm castings will have more microbes meant to live at normal temperatures when compared to compost. Although the process is not entirely understood, it is also clear that worms release more microbes than they ingest, meaning that they are actually creating microbes during their constant eating.

Many composters will tell you that you need a thermophylic reaction (140 degrees Fahrenheit / 60 degrees Celsius or higher) or pathogens will not be destroyed. Research has shown that castings produced in pathogen-rich environments, such as human biosolids (I’m glad I don’t research sewage) contain no pathogens. Dissections show that something happens within the first quarter inch (5mm) of the worm that completely removes pathenogenic substances. That being said, I do not recommend that any gardener feed their worms biosolids.

There are estimates that there could be over 1,800 species of worms worldwide. Many of the worm casting available in retail shops are produced by African nightcrawlers. However, for the urban gardener looking to start vermicomposting, this is probably not the right choice of species due to its specific growing requirements.

Eisenia Fetida, more commonly known as a Red Wiggler, is indigenous to most parts of the world. This particular worm is extremely tough and adaptable, able to handle a temperature range from 32-95 degrees Fahrenheit (0-35 degrees Celcius), and the eggs or cocoons can survive short periods of complete freezing. This species is commonly used in commercial vermicomposting and is easily accessed by hobby gardeners through Internet sales. Before you order your worms, you had better have somewhere for them to live. There are many small home-sized worm farm units available. Some are more efficient and complicated than others. Remember that vermicomposting is a type of farming, not an industrial process, so bigger isn’t necessarily better. A savvy gardener will want to master the basics prior to a significant investment in equipment.

The Experience (in brief)

My first experience with vermicomposting began last year when, to the horror of my colleagues, I placed a worm bin in my office. My boss was quick to inform me that if it started to smell that would be the end of it. The pressure was on, so I put in my bedding and a half pound of worms and started the feeding frenzy.

I placed approximately 44 pounds (20 kg) of food waste in the bin over 14 weeks. I was amazed at how quickly the worms processed material and everyone in the office was stunned that there was essentially no smell other than a mild earthy aroma. This first batch of quality vermicompost got me hooked, and I would like to pass this concept along as a suggestion from one gardener to another.

I have moved on from my office bin, which in the end was too small. I am going to move my worm adventures outdoors into a very straightforward continuous flow wedge. Essentially I am going to build a three-sided open-end structure made from straw bales. To begin, I will add material and then worms against the back wall. After that I will continue to put in bedding and food sources. Once the pile reaches the open end I will take the straw bales from the closed end and move them to the open end. At this point I will harvest the oldest material to use as vermicompost and begin moving the pile in the opposite direction. This will get rid of the issue of removing the worms from my compost because they will move into the fresh material as you take away the digested castings. This was an issue with my office bin where I had to take the castings out and create small piles, then remove the top layer as the worms retreated to the base of the piles. Follow this with taking the base of each pile (which contains most of your worms) and put it back in the bin with fresh bedding and food. You can always buy new worms every time you renew your bin, but this adds cost to the exercise. That money can be better spent on other things by keeping your worm population healthy and productive.

Giving Your Worms a Home

To manage your worms properly you need to consider five essentials:

1. A hospitable living environment: the best worm farms have the best bedding. Things like straw, peat moss, coir, newsprint, cardboard and even dried leaves all make excellent bedding and can provide different benefits when blended together. You are looking to create a moist environment with lots of air pockets and a high carbon to nitrogen ratio. I have found a blend of straw and coir to be an excellent mix. A pH range of 5-9 is acceptable with a level of 7 being ideal.

WORM WISDOM
Adding grit to your bedding can help worms process more material. Inputs such as soil, powdered limestone, rock dust, egg shells and zeolite can provide this abrasive material that worms use in their gizzards. Note that all of these items will also provide extra benefit when added to your soil-less mix as well.

2. A good food source: worms are what they eat, so your food source is very important. Vegetable and fruit peelings are excellent, and coffee grounds are great when available. Kelp meal is a good choice, but remember that worms are sensitive to salt. Corrugated cardboard is also a good food source because of the high protein glue used to bind it. Commercially, there are many more food sources, including manures; but for the urban gardener it’s fine to stick to what you might put in a standard compost bin.

3. Adequate moisture: worms need a damp environment to get the job done and be happy while doing it. The moisture content in the bedding should be somewhere around 70-90 percent. This means you may have to add water at the start, but as you pile the kitchen scraps into the bedding the moisture should balance out to a good range.

4. Worms need to breathe, so make sure there is a good level of oxygen. If bedding becomes too compact it will force worms out by creating an anaerobic environment, which kills worms and will smell like something you don’t want in your garden.

5. Protection from extreme temperatures. The Red Wiggler is a perfect worm for vermicomposting because of its temperature range. However, you need to keep direct sun off your bin or pile because it can overheat the environment. Remember, also, that direct sun is toxic to worms. Outdoor vermicomposting does require some shelter planning, especially in Canadian winters that sometimes spill into the northern states too.

WORM WISDOM
Space is premium in small urban gardens, but many worm bins are small enough to fit under the kitchen sink or under your flood table. Most common small units use a top feed bed where you are adding food material into the worm bedding as it becomes available. Looking to upgrade? Consider a vertically stacked tray system for even more castings out of the same area.

The Reward

So now you want to use some of the black gold that has been growing in your worm bin. The finished product will range from 10-50 percent of the original weight of the material. But don’t worry because the best ratio to mix into your growing medium is about 10 percent. You can add up to 40 percent, but using over 40 percent seems to decrease its value, and castings can then actually slow the growth of plants. Use it as a top dressing or mix it directly into your medium. As a growing tip, if you are simply looking to enhance the microbial diversity in your rhizosphere, then consider the use of an aerobic compost tea to enhance the levels of various bacterial species. Remember that vermicompost has a much broader diversity of microbes than standard compost, and they reproduce rapidly at room temperature, so to use it in an aerated tea is an exceptional way to stretch its value in your garden. Without question, the addition of worm castings provides urban gardeners with accelerated plant growth. And to those urban gardeners up for the challenge, small-scale worm farming produces a growth accelerator while decreasing the waste that leaves your house for the landfill. I hope that you see some of the benefits now, and will experiment to bring vermicompost into your urban jungle.

Simon Hart is the senior technical advisor for Grotek Manufacturing in Canada. If you have any questions regarding vermicomposting or anything else garden-related, post them below!

Countless people across North America are reconnecting with their food by making an effort to grow part of it themselves.  Some people are growing in their back yards.  Others are making use of a sunny balcony.  And some are taking the efforts indoors and growing food 365 days a year using grow lights.  Perhaps this recent spike in the popularity of the ‘Grow Your Own’ movement is a direct reflection of our concern over the global economy, or maybe the simple commonsense of local food production is beginning to naturally reemerge in our collective consciousness?  Whatever the case, like many others, I am making an effort to surround myself with more edible landscapes.  I’m learning as I go and having fun in the garden all the while.  My food garden is very unusual though – it’s in a forest.

I live on the West Coast of Canada – one huge rainforest – and I’m lucky enough to have a small acreage on what was once part of a family wood lot an hour outside of Vancouver, BC.  The Canadian Wildlife Federation has even certified my property as a wildlife habitat! Obviously, the special thing about living in the forest is the trees; so although I wanted to garden, I felt the responsibility of respecting the trees and all the biodiversity that coexists with them.  Being a temperate rainforest, the climate here is cool compared to tropical forests and this naturally limits plant selection and diversity.  While it’s important to work within your environment, it’s crucial to note that there are delicious, edible options no matter where you choose to garden.

Designing a Perpetual Garden

These 73 blueberry plants of 14 varieties could eventually produce about 1,000lbs of fruit per year.

My approach is based loosely on permaculture – a concept developed in the late ’70s which focuses on sustainable small-scale farming methods from the last 10,000 years combined with observations of functioning natural  ecosystems.  Permaculture is a complex form of garden management that works with the landscape by using topography and long term planning to create a garden that builds on itself to create a naturally chaotic equilibrium.  To look at a food forest is to look into natural chaos but that is entirely the point.  The natural world is quite disorganized, but functions as a balanced system.  This forward thinking garden design was developed by Bill Mollison and he was awarded the alternate Nobel Prize for his work.

The key to a perpetual garden is the use of perennial crops as your foundation.  Once established, trees and shrubs that produce fruit and nuts require far less work than annual crops and also provide the backbone on which to build a bio-intensive, layered garden system.  The most important point in the design stage is to create a multi-storey garden which provides a diverse group of plants, varied habitat and micro climates within the landscape.

Growing fruit is not a new idea, but my garden will be slightly unconventional.  Other than selective logging in the 1950s this land has never been worked.  I had to create the soil for my garden as I am growing in a flood plain with very thin topsoil.  The forest soil that was on the garden site was infested with Himalayan blackberry and had a pH of 3.7, which is more like vinegar than soil.  So I had to literally start from the ground up.

Before

My first job was removing large areas of invasive Himalayan blackberry vines by hand which was a thorny experience and took longer than I expected.  Because blackberries spread underground, if I had simply cut them down it would have made the problem worse.  Once the blackberries were gone it was time to start working on my first planting of blueberries, moving soil one wheelbarrow at a time to create raised beds.  In my initial raised beds, I used fallen cedar branches to create the sides. In subsequent beds, thanks to the abundance of river rock that covers the property I have used stone to define permanent fruit gardens. The beds don’t follow straight lines instead they follow contour lines away from the creek on the edge of my property.  The driveway, which winds through the fruit beds also follows topography; and the bed which meanders alongside acts as a swale to stop rain water runoff and helps it percolate into the raised bed.  I will take advantage of the gravel driveway (which releases radiant heat) to grow watermelons underneath my blueberries this season.

Soil Amendments

I amended all the soil for the raised beds with coir fiber, peat moss (untreated) and compost.  I have also used a variety of organic soil amendments such as alfalfa meal, fish hydrolysate, liquid kelp, worm castings and fermented soybean meal.  So far I have been using multiple organic inputs to provide extra nitrogen and other key nutrients, but this season I am also seeding legumes in open areas to incorporate into my onsite composting.  These legumes associate with nitrogen fixing bacteria which use nitrogen from the air to feed the plant roots they grow on.  I will be using white clover and lupines as a perennial ground cover under my berry shrubs.  Hairy vetch and fava beans will be harvested and worked into compost once or twice a season.  Supplemental nitrogen is probably the most important step to creating a self sustaining food garden, and these legumes offer a solution for onsite nitrogen while inhibiting invasive weed species from taking hold.  They also provide flowers for pollinators, and incredible mulch for the garden when mixed with fallen leaves.

After

I’m lucky to work with soil scientists – lucky because that means I can get my soil analyzed for free (which is how I knew that my soil pH was so low initially).  After nearly two years of management, my first blueberry bed now has a pH of 4.6 which is in an appropriate range for blueberries.  I should point out that any agricultural professional would have determined my land to be marginal for food crops due to the pH but I have successfully grown everything from Brussels sprouts to cantaloupe in my first two seasons in this garden.  I think this highlights the point that gardening should be about experimentation and learning from personal experiences and discovering what will work in your own unique situation.  It also shows that organic gardens can function effectively outside of the conventional agricultural knowledge base.

Dealing with Low Light Levels

My fruit garden only receives about six hours of direct sun a day during the summer because of the large trees.  This is less than what is recommended for most productive gardens.  However, I have found that all this means is slightly lower yields and less water consumption; lower yields can be compensated for by increasing the number of plants.  With watering in mind, I’ve made sure that all the beds are concave with higher sides to channel water.  They also slope slightly from one end to the other.  This keeps water from running off the sides of the beds and ensures the most impact from the water used.

Visually the fruit garden begins at the edge of 120 foot cedar trees. However, it continues under the canopy and into the dense shade.  By planting native fruit shrubs, I have found that it is possible to take advantage of lower light levels.  Behind the blueberries, evergreen huckleberries flanked by salmonberries grow in part shade.  In the deeper shade, are deciduous huckleberries and thimbleberries which still manage to produce a limited amount of fruit in the dense shade under the forest canopy.  Using native plants that require less light energy has provided a longer fruit season, and in addition has improved the habitat for beneficial wildlife around the garden.

I have had to make the difficult choice to use part of the sunniest area of the property to put in a wildflower meadow which I have seeded this spring.  Although this area will be agriculturally unproductive, I am experimenting with the concept that the increased diversity in habitat and blooms will encourage a wider variety of birds and insects into the area, thereby increasing the pressures on pests within the garden.

This season, I am planting grafted apples and pears and some hazelnuts to provide the 10-20 foot canopy which will shade parts of the food forest.  Vegetables will be grown in open areas: lettuce, carrots and potatoes in the shade; peppers and tomatoes in the sunnier spots.  Creating a perennial food garden is a long-term project, but I will watch patiently as the forest continues to grow, allowing me to enjoy the fruits (and vegetables) of my labor.

Simon Hart is the senior technical adviser for Grotek manufacturing in Canada.  If you have any questions regarding his forest food project or anything else garden-related you can email Simon at simonh@grotek.net

Don’t forget to tell us about your plant projects!  Email us at rant@urbangardenmagazine.com