Filling a raised garden bed with premium soil can quickly add up in cost, but it doesn’t have to drain your wallet. With a few clever techniques, you can save money, boost your soil’s vitality, and give your plants the best possible start.
One of the most ingenious solutions is hugelkultur, a time-honoured gardening method that transforms logs, branches, and other organic scraps into a thriving, nutrient-rich foundation for your garden.
What is hugelkultur?
The term hügelkultur (pronounced “hyoo-gul-kul-tur”) comes from Germany and translates to “hill culture” or “mound culture.”
The basic idea is simple: create a base layer of large woody materials, such as logs and branches. Layer smaller organic matter (leaves, straw, grass clippings) on top. Cover with soil and mulch.
Over time, the wood slowly decomposes, releasing nutrients into the soil, improving water retention, and fostering healthy soil life—all while saving you from buying as much bagged soil.
The best part? You can skip hauling home endless bags of soil and still create a lush bed.
Is hugelkultur right for you?
Before you get started, it’s important to remember that your fruit and veggies need around 300mm of good-quality soil to grow. You’ll also need around 100mm of space to add a layer of mulch. So, if your raised garden bed is 400mm or less, you can skip the hugelkultur and go straight to adding good-quality soil.
If your raised garden bed is higher than 400mm, read on to find out how to fill it cheaply. Here are some other raised garden bed mistakes to look out for.
Here’s how to use hugelkultur for your raised garden bed:
Step 1. Add logs and branches
Begin by laying down hefty logs and sturdy branches to form the base, then sprinkle in smaller twigs and a generous layer of leaves.
The woody debris is the core of your Hugelkultur bed.
Step 2. Layer organic matter
Next, pile on organic matter such as leaves, straw, and grass clippings, building a soft, nourishing blanket over the wood.
Step 3. Add garden soil
Now, you want to add a layer of soil to fill in the gaps. The quality of the soil isn’t as crucial in this step. Garden soil is fine. Ensure you still have about 400mm of space left at the top for good-quality soil and a layer of mulch.
Step 4. Cover with nutrient-rich soil
Cover with at least 300mm of soil rich in organic matter.
Step 5. Plant
Now comes the fun part: planting your favorite fruits, vegetables, or a burst of colorful flowers.
What is the best wood for hugelkultur in Australia?
In Australia, it’s advisable to use hardwoods for Hugelkultur beds. Hardwood species like eucalyptus, acacia, or other native Australian hardwoods are an excellent option because they are solid and resistant to decay. Ensure the wood is untreated and has aged for at least a few months to reduce the risk of pests and diseases.
What are the drawbacks of hugelkultur?
Hugelkultur has plenty of perks, but it is not without a few challenges to keep in mind:
- Building a Hugelkultur bed can be labour-intensive, especially when gathering and arranging wood and organic materials.
- The decomposition of the wood core takes time, so the full benefits of nutrient-rich soil may be realised after some time.
- Hugelkultur beds can be relatively tall, which might only be suitable for some garden spaces or may require additional soil.
What not to fill a raised garden bed with
When you’re filling a raised garden bed, it’s best to avoid anything that might harm your plants or mess with drainage.
Skip treated timber, as it can leach chemicals into the soil. The same goes for glossy paper or cardboard, which may contain inks you don’t want near your vegetables. Steer clear of plastics, styrofoam, and other synthetic fillers—they won’t break down and can block water from draining properly.
It’s also a good idea to leave out any weeds with tough, spreading roots, since they could take over your garden.
Drainage tips for raised garden beds
Good drainage is essential for a raised garden bed. Without it, water can build up, causing your plants to rot. To keep things flowing, ensure that your bed has drainage holes or open sides at the base, allowing excess water to drain out.
If you’re working on top of heavy clay, lay down a layer of coarse gravel before you start filling to help water escape. And if you’re thinking of lining the bed with plastic, be sure to punch plenty of holes in it first — otherwise, you’ll end up trapping more water than you let out.
Other cost-effective ways to fill a raised garden bed
Hugelkultur is a brilliant money-saving option, but it’s not the only trick in the book.
Bulk organic matter with topsoil – Fill the lower half of your bed with compost, leaf mould, or well-aged manure, then top it off with premium soil for planting.
Lasagna gardening – Build your bed in layers of compost, straw, leaves, and soil — just like stacking a lasagna — to create rich, crumbly soil as it breaks down.
Inverted sod method – Got grass where your bed will go? Dig up the turf, flip it upside down in the base of the bed, then add compost on top for a ready-made layer of organic matter.
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