- Doug Tallamy’s ‘Best Bets’: Native woody and herbaceous plants listed by number of caterpillars they host. A must for butterfly gardeners.
- ‘Plant Communities of the Georgia Piedmont’ by Connie Gray details many of the native plants and where they are found within each community.
I’ve been reading a number of books about permaculture recently. For those not familiar, it’s a set of guidelines/principles that seek to integrate human settlements into the natural landscape and make them sustainable. It’s still on the fringe of mainstream ecology and the scientific community has been hesitant to embrace it, and rightfully so, because it is more of a philosophy than a scientific discipline. That being said, I think it is a step in the right direction toward changing the way that we view and interact with natural systems.
The main tenet of permacultural principles that I think also meshes well with the scientific method is that of observation. Only by observing intact, healthy ecosystems can we know how the natural world works to produce clean water, humus-rich soils, nutrient-dense plants/fruits, and how it cycles death and decay into life and sustenance. Observation of the natural world can inform our decisions as to what plants belong where, and what species grow well together. This hits close to home for us at Beech Hollow, as our entire operation is an attempt to place native plants back into the landscape, but if the plants are put in an inhospitable environment they will perish and all our work will be erased.
In an attempt to inform ourselves, and later our customers and readers, as to the ideal environment in which to place the plants we propagate Pandra and I have decided to start visiting some of the intact fragments of the Piedmont’s varied ecosystems to observe just where each specie thrives. Pandra gave me an excellent book for Christmas to guide us on this quest: Favorite Wildflower Walks in Georgia by Hugh and Carol Nourse. It has us planning excursions to numerous public lands in order to get a glimpse of what the landscape once looked like, and hopefully how we can mimic nature with our plantings . I took a trip this past weekend to the Chattahoochee River National Recreation Area with a few friends to see if anything had started blooming yet. The CRNRA is fully engulfed by the massive sprawl that is Metro Atlanta, and yet these small pieces of land survive relatively intact in their natural state.
The hike I took was on the West Palisades Trail, which is within a mile of two major interstates, and surrounded by apartment complexes. Despite the urbanization around it, this trail will transport you from what is essentially a parking lot for a giant apartment complex to a bend in the broad river teeming with birds and the only sounds you’ll hear are the wind and the water. The bluffs across the river from this trail have their own trails system and rise about 300-400′ above the water, and in the summer months brave/foolhardy people jump from the lower bluffs into the frigid waters below as hundreds of kayakers pass through the shoals known as the Devil’s racecourse. On a windy day in February the only life on the river was of the avian variety:
In addition to this and other Blue Herons, we saw Canada geese on their way north, Mallard ducks courting on logs, and numerous sparrows and finches flitting about the wooded slopes. The main reason for the hike was to see some plants, and despite it being early February, we were not disappointed.
Trout Lilies (Erythronium umbilaticum) were blooming by the hundreds on the steep banks. Their tiny yellow flowers tend to blend in with the decaying fallen leaves, but once you see a few, the rest just jump out. These tiny, delicate plants take many years to reach maturity and flower from the corms they form deep underground.
We also saw several Trilliums (Trillium cuneatum) getting ready to pop open. These plants take seven years to reach maturity and flower when grown from seed. Sadly, many populations of these beautiful, but slow growing plants have been dug up and collected over the years, and they just can’t replenish themselves in the face of such rampant theft. Fortunately there are still quite a few that survive near this trail.
Look for pictures of these lovely, threatened flowers in the coming weeks as I return to observe and document the succession of spring blooms in this hidden gem of Atlanta.
Atlanta and the surrounding metro area are blessed with an abundance of trees compared to other cities of similar size. It’s unusual for a yard to not have at least a couple of trees shading part of it, which leads to the most frequently asked question at plant sales, “What grows well in shade?” While most people are thankful for the shade that these trees provide from the summer sun, the thankfulness turns to irritation in the fall because the trees drop their leaves and dead branches. Seasonal pruning of shrubs also creates piles of ‘yard waste’ that most people bag up and set on the curb. There is another option for disposal of this material that will enhance your garden beds and return the nutrients that the trees and shrubs have removed from the soil back to square one, thus completing the nutrient cycle.
Hugelkultur translates roughly from German as “mound culture” (so I’ve been told…) and was a common practice in Europe centuries ago. It is a technique that is regaining popularity with permaculturists and gardeners because it mimics the nutrient cycling that naturally occurs in forests. It also helps the soil to better retain moisture which reduces the need for supplemental watering of plants and helps them to survive prolonged periods of drought. Trees and other woody plants naturally accumulate and concentrate minerals from the soil as they grow, so by incorporating woody materials back into the soil these minerals are released and made available to plant roots as the materials are broken down by soil microorganisms. All-natural fertilizer, less watering, and healthy plants. Sounds like a win-win situation.
A hugelkultur bed can be started on the existing ground surface or can be partially buried depending on the desired final height. The photos in my example are from a vegetable garden bed that I constructed in my back yard using 1) Branches from pruning back shrubs, 2) Fallen leaves and small branches from oak trees, 3) Partially composted kitchen scraps and 4) The topsoil that I dug out of the bed area prior to starting. You will need some soil to cover the top of the pile, so if you want to start on the existing ground surface and end up with a raised bed you can either remove the top 2” of soil or find another area to borrow some topsoil. The latter option is a necessity if you start on eroded or clayey soils that lack a good topsoil layer. Once the necessary materials are gathered and the site chosen it’s time to get started.
I made my bed outline 3 x 8’ because that’s how big my other raised beds are, but your bed can be any shape or size. Rectangles are kind of boring, so don’t be afraid to get creative.
I saved the dirt I removed on a tarp so it would be easier to replace it once I finished.
Once I started hitting clay I stopped digging. I’m fortunate that my garden area has had 50 years or so to build up a nice layer of topsoil since the house was built, so I was able to go pretty deep. Soil transition layers vary widely, but once you hit clay or mineral soil you should probably stop.
Chopped up twigs, sticks, pruned branches, etc. go in the bottom of the trench. This was my first attempt at building one of these beds and subsequent reading has made me wish I had put some larger diameter branches/logs on the very bottom. The larger branches have more biomass, will take longer to break down, and have the ability to hold more moisture than the small stuff I used. C’est la vie. Next time. Water down the woody materials well before proceeding to the next step.
Partially composted kitchen scraps went on the wet branches. This is what I had available, but anything with a high nitrogen content, such as fresh manure, alfalfa, green grass clippings, or coffee grounds will work. The fresher and greener the better. My material was partially composted, so had lost some of that valuable nitrogen, but it was what I had on hand, so it was what went in. I drink enough coffee that it was probably 1/4 coffee grounds anyway, so I wasn’t too worried. The reason that high nitrogen material is needed is that the woody material is high in carbon, which is slowly broken down by fungi and microorganisms in the soil. These decomposers need the easy to digest simple sugars and nitrogen in the green material to build their bodies and secrete the enzymes that allow them to break down the more complex carbon compounds in the wood.
Soil goes back on top. That’s about 6-8” of soil, but as little as 1-2” would suffice. Just enough good soil so that plants can have a healthy root zone to start growing in until they are able to tap into the bounty below.
This is the bed as it is today with some pepper plants growing in it. I surrounded the bed with several large sections of an oak branch that came down during a storm a few weeks after I built the bed. It helped define the bed and prevent soil erosion during heavy rains. The soil has settled considerably as the woody materials have broken down.
My anecdotal evidence for improved moisture retention is that the pepper plants in this bed showed less leaf wilting than their counterparts in my other beds that are just straight soil on many hot summer afternoons. We also utilize woody debris (often tree trunks) in the propagation beds at the farm and our plants there are doing great. I see fungal mycelium strands running through those beds every time I weed or plant something new. Fungi break down the wood, and in the process create vast networks of mycelia (think of them as ‘roots’ for fungus) that transfer nutrients and water throughout the area. Most plants can “barter” with the fungi for nutrients in exchange for some of the sugars they exude from their roots. Search for “soil food web” if you’d like to learn more about this fascinating process.
So, there you have it: hugelkultur. Hard to spell, relatively easy to do. A little internet searching will help you to find people and sites more knowledgeable on this subject than I am, but I hope this was a good introduction and has gotten you to think about reusing the woody debris that property maintenance inevitably produces.