Grow Beyond Your Zone: Easy Hügelkultur Beds for Citrus, Olives, and More

My husband loves olives, so it was no surprise to me that he did not leave empty-handed when he saw some olive trees for sale at a local store. In fact, he left with one tree in each hand. Now, we have a small homestead in the Appalachian Mountains and sit just a little too far north of the best zones for growing olives. But, even so, I didn’t discourage him, because I consider myself an adventurous gardener.  This was a fun challenge for me to address, and soon I found a very intriguing solution: hügelkultur.

If you’re wondering what hügelkultur is, I like to think of it as a dry fire. It is a mound primarily built of wood and decaying organic matter, which generates heat and can therefore be useful in growing plants that normally would grow a zone or two warmer than your zone. For us, that means we have the possibility of growing zone 7-9 plants in our zone 6b region. The word hügelkultur is derived from German and literally means “hill culture”, or “mound culture”. While this raised-bed technique has probably been around much longer in some areas of Europe and Eastern Europe, it gained recognition in recent decades thanks to publications that featured it (largely inspired by Rudolph Steiner’s biodynamic agriculture philosophy) and gained momentum among permaculture advocates. I became aware of hügelkultur thanks to an Irish gardener who mentioned it in one of her videos. She said a fellow gardener in Ireland had been using hügelkultur beds to grow lemon trees. I was intrigued: if he could do it in Ireland, I can surely do it here.

We made two smaller hügelkultur mounds to plant the olive trees my husband purchased early in the spring and then we started another bigger bed that I have now planted with my citrus trees and also some lemongrass, ginger, and even a pineapple plant. I have hopes these will do well in the winter, but don’t plant your prized plant in the bed until you have experimented at least one winter with the hügelkultur bed and determined you can keep the plants warm enough. I did not plant anything in my beds that I would be devastated to lose. I have my frost blankets at the ready, or I may rig up some greenhouse plastic on a simple wood frame to help keep the heat level high enough in the dead of winter. You might want to consider keeping such things ready too as you experiment with hügelkultur.

Hügelkultur Step-by-Step

I am going to spell out step-by-step how we created hügelkultur beds on our farmstead. Some hügelkultur bed design is very elaborate and requires digging down into the soil, but I will present a method that I believe is easier and just as effective that requires no digging. We are largely no-dig when it comes to our gardens for multiple reasons including maintaining healthy soil structure, excessively rocky soil, and the sheer fact that it requires extra labor that appears to be unnecessary.

You will need:

• Logs. A variety of sizes is okay, we used some longer ones on the bigger bed and some shorter ones on the smaller beds. The logs can be old and rotting or freshly cut, the critical thing is that they make a good frame for your bed.
• Plenty of decaying organic matter. We have big woods on our property and collected leaves, twigs, and larger decaying branches. If you don’t have access to a forest, use grass clippings, straw, corn stalks, and other plant matter from clearing your garden at the end of the season. You could also use scrap lumber as long as it is untreated and chemical-free, and ask neighbors if you can have their bagged raked leaves in the fall. Around our farmstead, we say they’re called leaves because you’re supposed to leave them on the ground, but plenty of folks still rake them up, especially in residential neighborhoods.
• Sawdust. Not everyone may use this in their hügelkultur, but I think it is essential, especially if you are wanting to create warmer zone conditions. We live near a lumber mill and my husband fills up 80-gallon plastic bags from the free sawdust pile there a couple of times every month. If you don’t have access to a lumber mill, try to find some local woodworkers, even hobby woodworkers can generate a lot of sawdust and may be very glad to give it to you.
• Compost or bagged soil. You will need soil or compost to fill the holes in which you place plants in your hügelkultur bed.
• Mulch. A generous layer of wood mulch to finish the bed will help to trap moisture and heat in the lower layers.

Step 1: Plan the location of your bed. What are the sun requirements of your plants? I situated our olive tree beds in full sun, but I situated the citrus, pineapple, lemongrass, and ginger in a somewhat protected area that will receive filtered sun in summer and full sun in the winter when the leaves are off the trees. Find a location that receives plenty of southern exposure, which is especially critical during the cold of winter. You may also want to consider a screen of some sort to block cold northern winds. There is a large hill on the north side of our beds that should sufficiently protect us from direct north winds in winter. Lastly, I highly recommend situating any hügelkultur bed at a good distance from your home or any other building on your property. I recommend this because the decaying wood could attract insects that may damage a house. 

Step 2: Prep the ground and build a frame around your bed using logs, fallen tree trunks, and larger branches. We had to clear a small wooded area on our land to make room for our orchard, so we conveniently had a lot of nice logs and tree trunks. If you are putting the bed in a grassy or weedy area, I recommend mowing or weed-eating the ground first. You can then (optionally) place a layer or two of cardboard, newspaper, or brown paper, which is something I do with all of my raised garden beds because it helps keep weeding to a minimum. However, the depth of the hügelkultur bed is probably sufficient to reduce weeds that may try to push up from the soil level. I do not recommend digging or clearing the sod, partly because it’s a lot of extra work, and also because I believe that leaving the soil biome intact leads to greater soil health (we also have super rocky soil, so no-dig is appealing for that reason too). After prepping the ground, place the logs to make the frame of the bed. You may wish to layer several logs for a deeper bed, and you can also create nooks and ledges between the logs where you can plant smaller filler plants if you like.

Step 3: After the frame is built, begin filling it with twigs, leaves, and any other decaying organic matter you have on hand. There should be a variety of shapes and sizes of matter so that there are gaps and spaces which allow for airflow as well as spaces for roots to spread out.

Step 4: Fill the entire bed with sawdust. Our sawdust sat for a number of months, which should reduce the acidity somewhat and render it more pH neutral. However, if you’re planting acid-loving plants this won’t really matter too much. The sawdust will go down into the gaps, but it will not affect airflow and is soft enough to allow roots to still push into the gaps. The sawdust acts like insulation and generates heat quickly.

Step 5: Once the sawdust is in place, I think it is a good idea to water the bed thoroughly. This allows some settling and also brings the necessary moisture into the bed. If you notice areas of the bed that need more sawdust after you water, add some to fill in the gaps.

Step 6: Figure out the placement of your plants. If you’re just planting one olive tree in a smaller hügelkultur bed as we did then it’s pretty simple. Just form a hole with your hand in the center of the bed, add a little compost or bagged garden soil, and plant your tree. However, if you’re doing a larger bed, plan a little before you plant. I put the taller plants on the north side of the larger bed so that the shorter plants like the lemongrass, pineapple, and ginger will still receive plenty of southern sun.

Step 7: Dig holes with your hands big enough to fit your plant’s roots, plus some compost or bagged garden soil. I like to be generous with the amount of soil I add to hügelkultur beds. I use a blend of aged manure and compost.

Step 8: Mulch the entire bed with a couple of inches or so of a nice, fine mulch. We have a big pile of mulch on our property, as it ages and decomposes it becomes even better for garden beds. Just be careful, if you’re using a fresher mulch that hasn’t aged for very long, keep it well away from any softer stems and the base of plants that might be sensitive to the acidity. Around trees and woody stems, it’s usually fine to put the mulch right up around the plant, but with softer stems like tomatoes or ginger, you will want to keep the mulch a few inches or more away from the plant. I like to finish with mulch because it retains moisture and gives the bed a nice finished look. If you prefer, you could finish with chopped leaves, straw, or something similar that helps lock in moisture. Lastly, water your plants and admire your beautiful hügelkultur masterpiece!

Hügelkultur beds are very low-maintenance, low-cost, and easy to build. To keep the heat level up, dig a few holes in the bed once a year or so and fill them with sawdust. You can also add a layer of leaves and a little extra mulch every other year or so. After several years you may want to push decaying logs into the mound a bit and then put new logs around the edge.

I hope this article has given you some good pointers on using hügelkultur on your homestead or in your garden. If you’re an adventurous gardener like me, I know you will love experimenting with this method of raised bed building. I would love to hear what you plant and how it grows! I am planning to make hügelkultur beds for my tomatoes next year and would love to share with you how that goes as well as update you on the success of my citrus and olive beds.