
Why hügelkultur? Like much of Cascadia, I live in an area with heavy seasonal winter rainfall that results in a high water table or standing water mid-winter. Standing water in the root zones kills or stunts a lot of crops, delays planting and plant growth in the spring, and contributes to runoff issues in our waterways.
While winter flooding has always been an issue, increased development, deforestation and climate change, and increased regulatory challenges have turned the dial to 11 for lowland farmers. Last fall, the Snohomish Conservation District released a useful Wet Feet Farming guide to try to give local growers some viable agroforestry options: A valuable effort but home gardeners only need so many aronia berries and cider apples.
We bought one of these fields (on purpose) and have been working to restore its summer function as a hay field while respecting its winter role as a sponge. Despite it being a designated wetland, the previous owner had at some point tried to unlawfully fill the lot and reroute the drainage ditch, resulting in increased flooding across multiple ag properties. We worked with neighbors, King Conservation District and the King County ADAP program to legally repair the ditch, leaving us with huge amounts of unwanted woody debris and tailings. Out of desperation, more than anything, I decided to gather it into one place and make a hügelkultur bed.

Hügelkultur is a form of mound-based agriculture that has recently been popularized by the permaculture movement but is a much older form of technology. Various permutations can be found online and in books but the approach that is currently in vogue is to dig a small ditch, fill it with available large woody debris and top it with the soil removed from the ditch along with copious amounts of organic matter. We just piled the woody debris in a row, topped it with the excavated soil, topped it off with a full dump truck of compost, and let it overwinter. (This is definitely tractor work, not something you want to do by hand.) Then it was time to take it for a spin. Over the last two years, I have gone from worrying about a permaculture-fail to being completely sold on the concept for our region.
During the winter, our field gets wet. It no longer floods like it used to but you can still slosh around in parts of it. No tractor is safely getting in there to mow until May. When the field is waterlogged, the wood in the mound absorbs water. It then slowly releases that water to plants during the summer months. Meanwhile, higher on the mound, heavy seasonal rain drains through the soil, leaving the root zone sufficiently moist but not waterlogged. This allows the soil to warm more quickly in the spring and prevents overwintering and spring plantings from having to grow in cold, anaerobic conditions.
Lessons learned and strategies for the future

Over two years of growing in this bed, I have had some massive successes and made some mistakes. Here is what I have learned thus far:
Cover crop and fertilize in fall
When we threw this bed together, I did not really have a plan. If I am being honest, it was so low on the priorty list that I did not even take a picture of it being built. The first photo I have was from six months later, in April of 2023. Not much happening here other than some encroaching grass. This was an opportunity lost.

What I should have done that first fall was fertilize with organic fertilizer and plant clover as a cover crop. The first year, I had nitrogen tie-up issues related to microorganisims using the available nitrogen to build their bodies. Eventually, when they die, their bodies decompose and the nitrogen becomes plant-available. Until then, though, my squash seedlings had a rough start and I had to apply some liquid fertilizer to get them over the hump. Likewise, I missed an opportunity to plant a nitrogen-fixing cover crop that would have served two purposes. First, after growing and being chopped down as mulch, the tender leaves would have added nitrogen into the soil for the first year of production. Second, the plants would have been excreting microbe and fungi-promoting root exudates right out of the gate, promoting healthy soil life.

In Year 2, I drew on information from Oregon State University's Dry Farming program, which recommends applying fertilizer in fall in certain cases. The goal in dry farming is to get the plants in the ground as early in the spring as is safe in order to take advantage of spring soil moisture. In a dry spring, if organic fertilizer is applied just prior to planting, there may not be sufficient water for it to break down and become sufficiently plant-available. By fertilizing in the fall, the fertility is available for plants early in the season.
In the fall, I applied organic fertilizer where I was going to be planting garlic and shallots. I undersowed crimson clover as a cover crop everywhere else, even before I had harvested all of the crops. I also threw in some leftover cover crop blend, which included peas, vetch, clover, and annual and winter rye. I chopped and dropped the mulch around plants in the spring. The cover crop root system built organic matter and promoted healthy soil microbe populations. The chopped leaf matter served as mulch, protecting plants while adding nitogen to the soil. In the photo to the left, I applied an early chop and drop to where I was going to plant potatoes in a few weeks. This fall, I will top off the bed with a bit more compost and repeat this process.
Weed!
I think one of the biggest mistakes a person could make would be to ignore weeds in a bed. A few is one thing. If they eat your bed, they will rapidly smother your plants and you will not get the yield you want. Because we used the tailings from our ditch, the soil was filled with huge amounts of noxious weeds and reed canary grass. While it is never perfectly weeded, I do not let it get out of control.
Garlic, shallots, and onions

Garlic and shallots overwintered tremendously well on the plateau of the bed. For whatever reason, my Chesnok Red hardneck garlic outperformed my Silver White softneck variety. The hardneck garlic is some of the most robust and uniform I have ever grown, with incredible root systems. I fertilized in the fall prior to planting and then side-dressed again with organic fertilizer in the spring. I also applied crimson clover as mulch.

The major coup for the year was growing Walla Walla sweet onions without any irrigation. I purchase a set of transplants from Territorial Seed Co. and planted them mid-April. Where I had fertilized in the fall, I got full-sized onions without required a single drop of supplemental irrigation. Where I hadn't fertilized, I got plenty of smaller onions. Equally tasty but I will definitely be fertilizing the entire plateau of the bed this fall. This was an unexpected success. I have started overwintering onions from seed and will experiement growing them on the plateau over this next winter.
Shelling Peas

I am a new convert to bush shelling peas. I whacked four packets of Sienna peas on the sides of the bed, anywhere I had bare soil. In return, they fixed their own nitrogen, held themselves up, and we got an oversupply of peas for the year. I freeze-dried them and will enjoy them in soups and stews all winter. They rehydrate incredibly well.

Potatoes
These Red Norland potatoes grew themselves. A couple of weeks prior to planting, I mulched with chopped-and-dropped cover crop. I also fertilized with organic fertilizer. To hill up, I simply chopped-and-dropped more cover crop. Red Norland is a reliable early variety and they matured before soil moisture started to drop away. We had plentiful new potatoes and probably still have 2/3 of the harvest being held in the ground. I have not experimented yet with mid or late-season varieties. In areas with summer rains, it should be possible. In a Mediterranean climate, I am still growing my main-season crop with irrigation.
Zucchini, summer squash, and problematic pumpkins

Squash have never met a compost pile they wouldn't grow out of. Around the last-frost date, I soak squash seeds over night and plant them on a side of the bed. Zucchini and summer squash will produce all summer long. They might pause in the midst of summer heat but will pick back up with the first fall rain. Four plants are more than enough for our family of three.

Pumpkins. A conundrum. The first year, I planted pie pumpkins. They were goregous. They grew effortlessly. And they were just.....off. I don't know if they were simply underripe or if a lack of water resulted in toxic squash syndrome. What I know is that, even after having time to cure, the texture was always a bit too dense and eating them resulted in repeatable gastric.....distress. If I lived in a climate with heavy summer rains, I would not worry about this. Here, where we get very little rain between July and mid-September, I now grow my winter squash with irrigation.
Flowers

Sunflowers love hügelkulture. I planted some at the last-frost date in Year 1 and was rewarded with self-sowing plants in Year 2. I weed out anything in the wrong place. About the time I pulled my garlic and onions, the sunflowers were allowed to go wild. They are bird magnets.
I think you can whack any kind of drought tolerant flower or herb in a bed and just see what happens. Thus far, I have grown sunflowers, nasturtiums, calendula, and cosmos, because that is what I had on hand. Toss some seeds in the spring and be pleasantly surprised when they germinate in the fall and provide a late bloom!
Ongoing experiments: brassicas and tomatoes

Heading brassicas are notoriously finnicky. They don't want it too cold or windy. They don't want it too hot or they will bolt. Growing instructions always mention the need for plentiful water. I transplanted four broccoli 'Solstice' this spring. First, it was cold and windy. Then we had uncharacterstic weather in the 90s in May. Three of the four plants were stunted then bolted. The fourth, however, grew a small head followed by side-shoots that I am still harvesting at the beginning of August. I just keep removing any diseased lower leaves and the plant just keeps growing tasty broccoli without irrigation. Perhaps I will transplant a dozen starts next spring and get three productive plants?
I also have extra gai lan transplants tucked into the base of the sides at the last minute this spring. I have gotten a few decent shoots and look like I will get more in the fall. I am also potting up overwintering cauliflower and purple sprouting broccoli to tuck into the bed once the fall rains start.
Finally, I am experimenting with dry-gardening tomatoes. Spring King performed well in OSU's dry farming trials, so that was a good place to start. As of the beginning of August, the fruit are about half the size of those in my irrigated beds but the plants look vigorous and we'll see what happens next!

Parting thoughts
Every winter, we have doug fir, cottonwood, and big leaf maple trees crashing down in winter storms, providing us with all the free material we could need to build hügelkultur beds. Our area also has plenty of free compost. With a bit of tractor work, we could easily build and maintain highly productive beds that help us meet our needs without any supplemental irrigation, while allowing us to grow crops in areas with light seasonal flooding without disturbing the soil. In wet areas, care needs to be taken to not contribute to runoff issues by not overapplying compost or fertilizer. With judicious application and the use of cover crops, nutrients can be held in place until they can be used by the intended crop. Give your beds time to become productive, feed your soil microbes, try fall fertilizing, weed (!!!!) and you may find your hügelkultur bed outperforms your "real" garden. Mine did!

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