Filling Raised Beds: Affordable & Sustainable Soil Tips
Raised beds are a great way to grow vegetables—but let’s be honest, they’re not cheap. Not only does building them cost money but filling them with soil can add up even faster. When I built my first raised bed, I didn’t want to spend a fortune. We used old fence posts and leftover wood from a dismantled deck—anything we already had lying around.
And once it was built, the next challenge hit: how to fill the raised bed without buying dozens of expensive soil bags.
For me, it wasn’t just about saving money. I was also tired of all the waste that comes with buying new things—plastic packaging, especially related to shipping. It felt contradictory to invest in gardening, something so connected to nature, while creating so much unnecessary waste.
If you feel the same—excited to grow food but looking for a more affordable and sustainable way to do it—this is for you. I’ll walk you through practical, beginner-friendly ways to fill raised beds using what you already have, or can find for free or cheap, while keeping your soil (and conscience) healthy.
Why filling raised beds can be expensive
Raised beds need a surprising amount of material to fill—especially if they’re deep. A 1.2 x 2.4 meter (4×8 ft) bed that’s just 30 cm (12 inches) can just under 1 cubic meter of soil. That’s a lot of bags, especially if you’re buying compost or potting soil from the store.
When I first started looking into it, the price tag was enough to make me pause. Even with just a few raised beds, the cost of filling them “the proper way” (with high-quality compost and topsoil) quickly added up.
And aside from the cost, there’s also the practicality: lugging heavy bags, dealing with plastic packaging, and trying to find truly organic or chemical-free options can be exhausting. That’s when I started looking for other solutions—ways to build healthy soil without breaking the bank or relying on store-bought everything.
The good news? You don’t need to fill the entire bed with expensive soil. Plants only need good-quality soil in the top layer, where their roots are most active. The rest can be built up with other, often free, materials.
The Layered Approach: What to Put at the Bottom
One of the most effective ways to save money when filling raised beds is to layer the contents—filling the bottom with bulky organic material you already have access to and reserving the top for higher-quality soil.
This approach is inspired by hügelkultur (from German mound or hill culture), a permaculture method that builds beds from the ground up with logs, sticks, and other compostable materials. It’s perfect for gardeners who want to reduce waste and spend less—while still creating rich, fertile soil over time. Check out this article on by GrowVeg for more details.
What You Can Use for the Bottom Layer:
- Logs, branches & twigs
These create bulk, break down slowly, and help retain moisture deep in the bed. - Dry leaves & garden debris
A great way to use seasonal leaf fall or clean up from pruning sessions. - Cardboard (plain, non-glossy)
Helps suppress weeds and breaks down into carbon-rich material. Remove any tape or stickers. - Old compost, straw, or grass clippings
These help bridge the gap between coarse materials and finer topsoil. - If you live near the sea, seaweed or kelp can be a fantastic addition. I’ve personally used it in my own beds—just give it a rinse to reduce excess salt and layer it in like mulch.
Tip: The bottom layer doesn’t need to be pretty. Use what you have. The goal is to take up space and create a foundation that will gradually decompose and nourish your plants.
The Middle Layer: Compost and Leaf Mold
After your bulky base layer, the middle section is where you start adding nutrient-rich materials—things that are either already partially broken down or will decompose quickly.
This layer acts as a bridge between the coarse bottom and the fine, seed-friendly topsoil. It also starts contributing real nutrients as it breaks down over the season. I mix these components with my native sandy soil.
Great Options for the Middle Layer:
- Partially decomposed compost
If you have a compost bin or pile, even if it’s not fully “finished,” this is a perfect spot for it. - Leaf mold
If you’ve been piling up leaves somewhere and letting them sit, this dark crumbly material is gold for your beds. - Old potting mix
Reusing soil from last season’s pots or containers? Add it here. Even if it’s depleted, it still adds structure and helps bulk things out. - Grass clippings or kitchen scraps
Use sparingly and mix well to avoid smells or pests. Avoid adding anything too fresh in large quantities. - Manure (well-rotted only!)
If you have access to aged animal manure, it can add excellent nutrition. Just make sure it’s fully composted to avoid burning your plants.
What to Avoid:
- Meat, dairy, or greasy food scraps
- Diseased plant material
- Weeds with seeds (unless you’re sure your compost gets hot enough to kill them)
This middle layer can vary depending on what you have on hand, but the goal is to start enriching the soil zone while still keeping costs low and materials sustainable.
The Top Layer: Invest Where It Counts
The top 10–15 cm (4–6 inches) of your raised bed is where your plants will actually grow, so this is the layer to focus your budget and effort on. Even if everything underneath is a mix of logs, leaves, and compost, this top layer should be nutrient-rich, loose, and well-draining.
Good Options for the Top Layer:
- High-quality compost
Whether it’s homemade or purchased, compost adds essential nutrients and microbial life to your soil. - Organic potting soil or raised bed mix
If you’re buying soil, look for organic mixes without synthetic fertilizers. Choose something with good structure—light, crumbly, and not overly compacted. - Topsoil (if available and affordable)
You can mix topsoil with compost to bulk up your top layer without spending too much.
Personal Mix:
I often combine what I have—part compost, part store-bought potting soil. It doesn’t have to be fancy, just workable and healthy.
Water It In and Let It Settle (Just a Bit)
Once your raised bed is filled, give it a deep, thorough watering. I would even recommend to water in between layers. This helps them start settling into place and gives you a better sense of how much the material may compress. You might notice the level drop slightly over the next day or two, especially if you used lots of lightweight or dry material.
As long as your top layer is deep enough and well-prepped, you can plant right away. Just be aware that things might settle further over time, and you can always top up with a bit more compost or mulch as needed.
Final Tips and Encouragement
Filling raised beds on a budget takes a little creativity and patience—but it’s totally doable! By using what you have, layering wisely, and focusing your investment where it matters most, you can build healthy, fertile soil without breaking the bank or harming the planet.
Gardening is a journey. The soil will improve with each season as the layers break down and feed your plants. Don’t stress about perfection—start simple, observe how your plants grow, and adjust as you go.
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