Tuesday, February 10, 2015

Adventures in Gardening: Hügelkultur Experiments

Periodically, I write about gardening on this blog. I'm sure some readers scratch their heads and wonder why, given that I generally focus on issues pertinent to weight or on pregnancy/birth/breastfeeding, but I view gardening as part of the mission of this blog too.

I write about gardening for several reasons. First and most importantly, I write about gardening as part of my Health At Every Size focus. I think it's obvious that as a society, we would be better off if we ate fewer processed foods and more whole foods, and gardening is an important part of the "slow food" movement. It promotes better nutrition and gives us exercise, all in one convenient package. Not that we all have to be perfect or obsessive, but striving for more whole foods is just common sense.

Second, I write about gardening as part of my Parenting focus. Kids will eat more vegetables and fruit if they help grow it themselves, and it's good for kids to appreciate the kind of work it takes to provide the food we eat. Far too many kids have no concept of how food reaches their table. Gardening also helps kids connect with nature, gets them outside, gives them exercise, and helps them learn to care responsibly for living things. I think every child should learn to garden in one degree or another.

Finally, I write about gardening as part of my Emergency Preparedness message. It's important as parents to have a stock of food on hand in case of a natural disaster or other emergency. Too many people are completely dependent on grocery stores for all their food, and most have very little stored food in reserve for emergencies. Gardening helps you have a renewable source of healthy food for your family. Gardening also lends itself to preserving, which helps you keep a stock of preserved food around. It's important that we keep gardening and preserving skills alive for our children, and it's also important to have a food reserve for our families in case of an emergency.

Gardening is a win-win all around on so many levels. Even though it might not seem like a logical topic for this blog on the face of it, it really does fit my blog mission too.

Today I wanted to share about a gardening experiment I've been toying around with this year. It's called Hügelkultur gardening.

Raised Beds on Steroids

Since a big car accident a few years ago significantly damaged my knees, I mostly garden in raised beds now. Saves my knees a lot of grief and my back likes it too. I'm a real fan of raised beds.

But raised beds have challenges too. They are more watering-intensive; they dry out sooner and need to be watered more often. Being the lazy, less-than-attentive gardener that I am, I'm not always good about watering regularly, which can be stressful on the vegetables.

Also, the soil in raised beds can get "tired out" and depleted of nutrients if you don't refresh them regularly. I prefer to garden organically, so I've been experimenting to see how I can best "feed" the soil in my gardens without having to resort to artificial fertilizers or additives.

It was in response to these challenges that I began to learn about a new/old technique called Hügelkultur Gardening (pronounced HOO-gull-cul-ture). 

Hügelkultur Gardening Basics

First layer of hugelkultur bed - pieces of wood in various
sizes. Image by Jon Roberts, from Wikimedia
Although Hügelkultur gardening has been practiced in several different cultures, the name is German and the idea was popularized by permaculturist Sepp Holzer.

Basically, it means "Mound Culture" or mound gardening. You pile a bunch of wood in various stages of decomposition at the bottom of the pile, water it in well so the wood soaks up the water, then add other layers of soil, kitchen waste, leaves, straw, compost, manure, bark chips, etc. until you have a mound. Then you plant in that mound.

Sometime the mound is small, sometimes it's large, but you basically are planting in a compost pile that's in process. Using different sizes of wood means that it processes slowly and that the nitrogen from the kitchen waste etc. does not overwhelm the carbon content, which is a common problem in many compost piles.

The benefits of hügelkultur are:
  • it improves soil fertility (through decomposing organic matter)
  • it aerates the soil and improves its structure (the soil around the logs naturally creates air pockets, which helps keep the soil from compacting to much, thereby improving its structure)
  • it improves water retention (water is released slowly over time from the water-soaked logs, necessitating less watering in the drier months after the first year or two)
  • it warms the soil (making it easier to plant earlier and longer in the growing season)
  • it promotes earthworms and other beneficial animals/fungi in the garden (they are attracted to the decomposing organic matter and help break it down)
Permaculturists like hügelkultur because it recreates replenishment of soil in the garden in the same way that it happens in nature:
Hügelkultur replicates the natural process of decomposition that occurs on forest floors. Trees that fall in a forest often become nurse logs decaying and providing ecological facilitation to seedlings. As the wood decays, its porosity increases allowing it to store water "like a sponge". The water is slowly released back into the environment, benefiting nearby plants.
Image from richsoil.com 
Personally, it's the watering benefits I'm most interested in. While my area of the country gets lots of moisture in the winter, we get very little during the summer, so we have to do a lot of watering in the summer. My new hügel bed is on the side of my house that doesn't have easy watering access, and it's far away from the raised garden beds that get my main (if inconsistent) watering attention. I wanted more gardening space but less upkeep, so I'm hoping the new hügel bed will help by giving me a new garden space that I don't have to spend so much time watering.

There are lots of different ways to do hügel beds. Although it is helpful to read up on ways to optimize the process, it's basically just planting into soil mounded over buried wood. Some online accounts make it seem complicated, but if you keep in mind the basics, the process is pretty forgiving.

Some people like to build their hügel beds in a trench. You dig a long hole, pile up woody debris in it, then fill in the gaps with kitchen waste, compost, straw, etc. until you have a good mound. The digging part can be a lot of work, so some gardeners don't bother with the trench; they just pile the woody debris directly on the ground and then fill in the gaps. Personally, I used a trench because I think it gives more stability to the mound and because putting the wood directly in the earth accelerates its decomposition, brings more worms, and enhances water retention in the dry months.

Some writers suggest building your hügelkultur beds to run in a line north to south. This is to maximize sun exposure (otherwise, the mound nature of the bed means one side of an east-west bed will get too much shade). Some surround the base of the hügel mound with rocks, logs, or other materials for stability and neatness; others do not. Rocks along the edges may help warm the soil better, but otherwise it's a personal choice.

It's important to use different sizes and ages of wood in the bed if possible. You want some to be old and partially decomposing already, some to be new, some to be thick pieces of wood, and some to be small thin twigs and branches. If you start with all-new and thick wood, your hügel bed may not do as well for the first couple of years, since it needs time to absorb water and start the decomposition process. For maximum benefit, use wood of various sizes and states of decomposition, and start your hügel bed in the fall so that the wood can absorb the winter moisture before planting in the spring.

If you don't have enough woody material of your own, look around. Tree-trimming companies, power companies, and government agencies often have some you can get, or you can collect fallen wood from a friend's back yard, etc. Just make sure it's untreated wood. No plywood or treated lumber should be used.

Another suggestion I've read is to put some of the wood in vertically instead of horizontally, especially if using less water is one of your priorities. Supposedly the wood wicks moisture more efficiently if it's vertical instead of horizontal. I can't speak to this but it seems plausible to me.

Some authors also suggest adding alfalfa pellets when building the bed in order to add more quickly-available nitrogen to balance the carbon dominance of the bed in the first year or two. If you don't have much manure available, this might help. After that, the wood should start breaking down and create its own balance of carbon and nitrogen.

(As an alternative, some people suggest pouring diluted urine or peeing directly onto the logs, but surprisingly, my teen-aged boys declined to do this. I thought they'd love the chance to mark their territory but they were absolutely appalled by the idea.)

Alternate layers of greens and browns in your pile, like in "lasagna gardening" (sheet mulching). Use kitchen waste, garden waste, bark chips, manure, straw, grass clippings, whatever you have on hand. Top it all off with a thick layer of compost and then straw or other mulch to help keep the soil in place and hold in moisture. When you plant, simply move aside some of this top layer and plant the start (or seed) directly into the pile. When you see the seedling is high enough, put the mulch back around it. The first year or two you will have to water seedlings more often, but after that you should have to water much less often.

The more organic material you add (especially nitrogen material) on top of the wood, the sooner your bed will produce results. If you have mostly woody material with minimal soil, it's going to take a couple of years to start breaking down and you won't get much results until then. But if you start with well-watered wood in all stages of decomposition, then add lots of nitrogen-rich material and soil layered with smaller carbon materials (like straw or bark chips), you should be able to plant in the first year and get reasonable returns.

Each year, the organic materials will break down more and more, so you'll need to occasionally add more compost, leaves, manure and bark chips to the hügel beds over the years. Just fill in the holes periodically. The best growing results are typically several years into the process.

But really, although these are suggestions to make hügelkultur more efficient, there's not a lot of strict rules to follow. It's a very forgiving approach, which is why I like it. You can make it what you want and adapt it for your own needs.

My Hügelkultur Beds

Hügelbed, minus top layer of soil.
(This is not my hügelbed, but mine looks
a lot like this, not very mounded yet.)
Image from Wikimedia.
Personally, I started my hügel bed in a small trench and filled it with fallen tree limbs, some firewood, and some old branches and logs from our school grounds. (If I were to do another hügel bed, I think I'd add in even more wood, as I don't think we have enough in there to truly go without extra watering.)

My hügel bed is more of a mini-hügel than a true hügel. The classic hügel is a very high mound with very steep sides. I do not have enough soil and compost right now to make a mound that high, so I'm doing what works at my property...a mini-hügel. It won't last as long, but it should still last several years. That's good enough for a first experiment.

I let the wood get good and soaked in the fall rains, then we began covering it up with layers of kitchen scraps, manure, straw, wood chips, grass clippings, half-cooked compost, the original soil from the trench diggings, garden leftovers, and dead leaves. At this point, it's not very mounded yet, so we need to add more compost, straw and other materials this spring to continue to build it up.

The top of the pile has last year's Halloween pumpkins on it; I'm hoping they seed and start new pumpkins in the pile for this year. Pumpkins are supposed to love hügel beds. My hügel bed is in the former rabbit pen, so it should have lots of good rabbit poo to make the pumpkins happy, and the pumpkins will have lots of room to spread out and grow, which was a problem in my raised beds.

I plan to plant several berry bushes of different types in the hügel bed this year, mostly huckleberry, josta berries, and blueberries. These will form the backbone of the hügel garden, the "perma" in my permaculture. Their root structures will hopefully grow strong over time and give stability to the bed.

Some people also put stuff around the edges of the bed to give it stability, but since mine was built in a trench and isn't very mounded, I'm not too worried about this. I probably will put down some cardboard and bark chips around the edges of it to create a walking path and hopefully deter the grass from growing up the sides, though.

I will plant some nitrogen-fixing plants like peas and beans this year, which hopefully should help provide balance for the carbon in the wood pile underneath. This may be especially important in the first year of growing, since a hügel bed tends to be carbon-dominant at first. I didn't add any alfalfa pellets, but I may look into getting some to add to the beds (since my teens aren't cooperating with territory-marking plan).

In future years I will add more variety of plants, intercropped between the more permanent plants, but for now, I just want to get the basics in the bed and get it up and running. I'll probably have some annual greens there this year as an interim plan.

I like the hügelkultur idea so much that I'm trying to convert some of my raised beds on the other side of the house to a hügelkultur hybrid bed. I have my teenagers digging up the dirt in the raised beds, shunting it to the side, putting old soaked wood and branches in the bottom, and then mixing in kitchen waste, half-finished compost, rock/mineral dust, straw, bark chips, and manure into the rest of the soil. They won't be true hügelkultur beds because they won't have nearly as much wood, but will hopefully give my raised beds a good shot of soil replenishment ─ and maybe lessen watering requirements if I'm lucky.

I wrote previously about my experiment with trench composting, i.e. composting my kitchen waste directly into holes in the raised gardens. Overall, that has been great (far better than messing with a compost pile!), but I did notice that some of my raised beds tended to have too much nitrogen this year. As a result, some of my tomatoes had tons of green growth but not as much fruit in some places.

So the hügelkultur hybridizing of my raised beds will hopefully also help bring more carbon to balance the nitrogen created by the trench composting, which I love and want to continue. Hopefully, a better balance between "browns" and "greens" in the garden will create maximum produce production.

Although it's still early in the process, I'm pretty optimistic about the Hügelkultur beds I'm creating. Since it simply re-creates the process as it happens in nature, I think it has a great chance of succeeding and will greatly add to the productivity of my garden. Better yet, I'm hoping it will lessen the amount of watering, fertilizing, and fussing I need to do, which would be great because I'm a very lackadaisical gardener. I enjoy it when I get around to it, but I have too many other time demands and interests to obsess about it too much.

If you are interested in Hügelkultur for your own gardens, check out some of the links below. Happy gardening!



Kirah said...

Thanks for this very interesting post. I'd never heard of this process but now I'm thinking about where to get enough wood to try it out ;)

Anonymous said...

I just wanted to agree that kids get excited about gardens. I have a brown thumb but managed a tiny 3x5 garden last summer, and my 2 yo daughter loved it! I could barely keep the carrots in the ground because she was so excited to pull and eat them.