Plant Guilds

     A guild is a grouping of plants that compliment each other in some way, or hopefully in more that one way.  It is really a natural extension of the concept of companion planting.  My favorite definition of companion planting is "a collection of facts and folklore concerning the relationships between plants".  I think it's important to remember the folklore part of that definition.  Not that being folklore makes a thing necessarily untrue, but often the mechanisms at work can be misunderstood; and there is so much we don't understand about the relationship between plants. Still, there are some things that we do know which can be very useful in arranging garden plantings.  I think it is a huge step forward as a gardener to have this realization.  That each plant has different needs from and effects on the other plants and animals around them.  Then, getting to know each species as individuals becomes a worthy, though endless, endeavor.

     Our young Bing cherry tree guild, pictured above, offers a good example of some basic plant guild concepts at work.  Arguably the most important family of plants is the legumes, also known as nitrogen fixers, represented here by the lupines to the right of the tree.  These plants work symbiotically with bacteria in their roots to take nitrogen from the air and "fix" it into the soil in a form that is usable by other plants.  Since our atmosphere is somewhere around 70% nitrogen, and since nitrogen is the nutrient that the majority of plants need the most of, it seems like a no brainer to always have some type of legumes around the garden to fertilize for you.  It is a huge family of plants ranging from the tiny clovers to black locust trees towering over 100' tall and every size in between.  There are even edible legumes including all peas and beans.  This family of plants will give off some nitrogen during life.  But, if the roots are left in the ground, can continue to feed the plants around them for years afterward.

     Out of sight behind the lupines are several large dandelions.  We didn't plant them.  As most people know, they are really good at planting themselves.  Most people around here hate them, and go to great lengths to eradicate them.  Often resorting to dangerous chemicals that add stress to their already overworked natural body defenses and affect the environment at large in a similar way.  I think dandelions are awesome, and beautiful, and they play an extremely important role in nourishing our young cherry.  They are one of many plants that play the role of dynamic accumulator.  Dynamic accumulators have deep tap roots that can reach way down to sub soils where vast amounts of nutrients have washed down, out of reach for most plants.  In the case of dandelions specifically: Phosphorus, Potassium, Calcium, Magnesium, Iron, Copper, And Silicon are all brought to the surface and into the leaves.*  The leaves die back in the autumn automatically depositing nutrient loaded mulch on to the surface.  It's like having my own army of fertilizing robots.  No wonder the lawn chemical companies want us to wipe out the mighty dandelion.  It's probably similar to the reason everybody stopped including clover as a feeder in grass seed mixes in the 60's when chemical fertilizers hit the scene.  There are many other dynamic accumulators including comfrey, fennel, and parsley to name a few.  The lupines act as both legumes and dynamic accumulators, bringing Phosphorus to the surface as they fix Nitrogen from the air.

     The garlic on the left is also a dynamic accumulator, providing Manganese and Sulfur, but the main reason we have it there is for it's ability to repel pests.  Garlic seems to drive grubs and other critters from the soil, including the dreaded Japanese Beetle, which totally defoliated this tree the year we planted it.  Garlic is our first line of defense here, and we basically have it planted everywhere.  Not only is it a delicious addition to a huge variety of recipes, it is an important medicinal plant as well.  Garlic seems to drive illness form the body just like it drives grubs from the soil.

 

     Pictured above in the center foreground you can see the distinctive silvery green leaves of a daikon radish.  This annual vegetable is serving a role here other than food for us.  Although we could harvest and cook it's root for dinner, instead we will leave it in the ground past maturity to serve as a Soil Buster.  This plant has a deep and very powerful tap root, that can penetrated compacted soil, heavy clay, even stone in some cases.  The root can grow quite large as it creates a path downward.  We will leave it in the ground, where it will rot leaving a column of organic matter that less aggresive roots can use to reach deeper.  Worms and other composters will also follow this path, mixing the organic matter from the soil buster into the clay and rock as they go.  This is tilling with a surgical precision at depths measured in feet instead of the  few inches our clumsy mechanical tillers and plows can reach.

       There are other important interactions going on as well.  All of these plants provide shade, acting as a living mulch to prevent the sun from evaporating water out of the soil below.  In turn, the shade from the tree helps the plants below in the same way, up until that point where they are not getting enough sun to thrive anymore.  The plants offer shelter to a host of beneficial insects that we depend on in a variety of ways.  The blossoms attract pollinators and feed tiny parisitic wasps that are critical for managing catarpillars.  Then lets not forget the benefits to us!  Of course most of these elements are offering us food, but I also appreciate the beauty and scent of the flowers and some shade too.  The best part is that they are doing all the heavy lifting of fertilizing, water management and weed control for us. 

     So there you have it.  A simple example of a plant guild and some of the terms we use to identify the interactions happening.  This is a vast subject, that is unique to each location due to differences in climate, soil compostition, moisture, and a host of other factors.  It is very exciting to me to be experimenting in this young but growing field of study.  Thankfully, we have the luxury to experiment right now, and are not dependant on our garden to survive.  Having the unprecedented ability to share information about these experiments gives me great hope for the future, as we begin to face the challenges presented by limited energy and an unstable climate.

[* Source: Gaia's Garden, by Toby Hemenway]

Online Resources:
An explanation of guilds from TC Permaculture.
A free Plant Guilds E-book from Midwest Permaculture

Related Books: