How to Fill a Raised Bed Ideas

Raised Bed Ideas

Raised Bed Ideas.The raised beds are built and now it’s time to fill them. But if you’re not careful the cost of the soil can far exceed the cost of the bed. Join me as I show you how I fill raised beds and save some money in the process. Hi, I’m Gardener Scott. And this is one of my raised beds that I’m about to start gardening in.

If I were to go to one of those big box stores and buy bags of garden soil to fill this bed, just how much it would cost to fill it? Go ahead and think of a number? I can almost guarantee you that number is too low. Buying bags to fill this with a name-brand product would be close to $300 and I don’t want to spend anywhere near $300 on filling this bed. I can do it for 50. I can do it for 40. And if I’m lucky I can do it for almost free. And that’s what I’m about to show you. So you may be thinking that my math is completely wrong that there’s no way this bed could cost $300 to fill.

Raised bed dimensions

Well, let me show you how I arrived at those numbers. I think it’s very important that you have an idea of how much soil it will take to fill a raised bed that you create. This bed is 4 feet by 8 feet long. 4 by 8 means that this is 32 square feet. Most beds aren’t this deep. Mine are this deep because I’ve got rabbits that I don’t want jumping into the bed. So let’s go with half of this height, which is more typical in home gardens. This is a 2 by 10. I’m not going to fill it all the way to the top, but let’s say you have a bed close to this size. Then you fill it mostly full with soil to a depth of about 9 inches.

Well, 9 inches is 3/4 of a foot… 0.75. So if we take the 32 square feet and multiply it times the .75 depth, we come up with 24 cubic feet. So it will take 24 cubic feet to fill half of this. Those are the numbers that I’ll be using. Realize that I’m talking about a double bed. So when we get to the end, I’ll show you where that 300 really comes from.

Choosing top soil

Many gardeners when they fill their raised beds just go to the store and buy a bag of garden soil. So that’s what I did. I went to Lowe’s to see what they had to offer for garden soil. And I’ll be comparing a few bags, but let’s start with this bag of Miracle-Gro garden soil. It’s 0.75 cubic feet and it costs 4 dollars and 28 cents. Well for that 24 cubic foot space that I need to fill, I would need 32 bags of that garden soil. You do the math, that adds up to one hundred and thirty seven dollars to just fill half of this bed. That’s where I came up with that $300 because if I were to go with that, just that garden soil alone would cost two hundred and seventy five dollars, roughly, to fill this bed.

I don’t want to spend that much money, but here’s another option. Let’s look at this bag of Miracle-Gro garden soil. This one is twice the size. It’s 1.5 cubic feet that sells for $7.98. Well if I buy this option, I’ll need 16 bags. But it’ll still cost about a hundred and twenty-seven dollars to fill just half of this bed. That’s a little bit more money than I’m really looking to spend. You can shop around for better prices because Miracle-Gro is a premium brand. Here’s a bag of Sta-Green garden soil that sells for a little less than four dollars. It is a one cubic foot bag.

How many bags

Now, it’ll take twenty four of those bags to fill this bed. So that means for $100, a little bit less than that, I can fill half of this bed. It still cost me $200 to fill the whole thing. That’s a lot of money. The cheapest option that I found at this Lowe’s was for bags of top soil which sold for less than $2 per bag. So to do this top half, the 24 cubic feet, I could use those bags and spend less than 50 dollars. But that raises an interesting question because when you look at the bag of topsoil, nowhere on the bag does it say what’s in the bag.

In most places, especially here in Colorado, there are no regulations to define what “topsoil” means. So they can put whatever they want in that bag and they don’t have to label it. At least in all of the other bags they identify what’s in the bag. So for this Sta-Green or the Miracle-Gro, they’ll tell you that their bags contained compost and peat and coir and composted forest products. All you have to do is look at the back of the bag and you’ll know exactly what you’re getting. I’m a little hesitant to buy a bag that I have no idea what’s inside. But that is one way to save some money.

Three ways to fill beds

o what do I do when I want to fill my beds? Well, typically I’ll use one of three methods. And for these beds I’ll be using two of those methods. For the bottom half I’ll use the free method. I’ll fill it with soil that costs me nothing. Because this deeper section won’t have a lot of plants growing in it. So why spend hundreds of dollars just to fill that bottom half? I’m more concerned with the top half and that top half I’ll use the second method and save a ton of money as I do it. And for that third I’ll show you what you can do to save money and get exactly what you want in your raised bed. For all of these methods there’s hard work involved.

Unless you hire it out, you’re going to have to fill these beds, usually with just a shovel. That’s what I do. Where you place the beds can be important. So I suggest if you really want to save money dig out the area underneath the bed. If you’re going to place it on lawn, well, then dig out all that grass. If you’re going to place it in a bare area, then dig out some of that soil before you place the bed where its permanent location is going to be. And the very first thing you do after you place it, is level it. Make sure it’s level on all four sides.

Level raised beds

Because you really don’t want a tippy bed so that when it rains all the soil from the top is going to run down to the lower section. Make sure it’s level. When it comes time to fill it, the depth of your bed does make a difference. Now, I’m going to jump to that second method first, the one where you save money, but it’s not free. For many gardeners that have relatively shallow beds, what I recommend is to purchase a soil blend. Because I’ve got a lot of space and a lot of beds that I’ll be filling, I actually ordered it in bulk, by the dump truck load, and had it delivered.

When you have it delivered or you buy it yourself in bulk, you can save huge amounts of money. So the soil blend that I’m using in most of these beds is topsoil, compost and humus, as a blend. And it averages out to less than thirty dollars for the amount of soil that it’ll take to fill half of this bed. Much cheaper than I can get with any of those name-brand bags. And even cheaper than that mystery topsoil. At least I know what the blend is that I’m getting. Even though I can save a lot of money by buying the soil in bulk and know exactly what I’m getting, I still don’t need to fill this bottom half of a tall bed like this with anything that I purchased.

Filling bed for free

I want that free option and the free option is something that you can take to fill your entire bed. You may have seen my video on Hugelkultur. Which is basically taking logs and branches and covering it with soil and nitrogen materials to create your own garden soil. You can do that inside a raised bed. And that’s what I’m doing in the lower half of this bed. I’m taking branches and twigs and small logs. I just pull them into place and fill the bottom half with all of these old dried branches.

The next thing I do is to take all that soil, all the grass, all the weeds, whatever it was you dug up, and then cover all of those branches with that old crummy dirt. And as it all decomposes and works together you’re creating a soil that you can grow in. And as I’m putting all of that bad dirt on top of all of these branches I’m also adding other things like grass clippings. I’m just taking the bags of grass that I have and spreading it over the entire mix. I’m adding organic material to create my own good organic garden soil. Add whatever organic material you have available at this point. Add the horse manure that you might have access to or maybe the chicken droppings from the coop.

Everything can go in

Bags of leaves, the bags of grass, all of that can go in as you’re adding that old grassy weedy soil to all of these branches. And as it all decomposes and mixes together you’ll be left with a wonderful soil for free. Remember, I’m just doing this in the bottom half, but you could be doing this in the top half as well. Or you could be doing this exclusively as the soil that you’ll be growing in and it’ll cost nothing.

The third option

The third option I mentioned is kind of a mix of the first two. If you don’t have enough of the free stuff lying around to fill the bed or you don’t want to buy a blend to fill your bed, well, now you take some purchased product to mix in with your native soil, and your leaves, and your grass, and whatever you’re using. I like peat moss. It’s readily available. It’s inexpensive. It might not be the choice for you in the area you live, but I can get this three cubic foot bag for less than four dollars a cubic foot and it goes a long way. I like to jump start the process by using compost.

Now, I don’t have enough compost made yet. If I had my own I would definitely use it and that adds to that free aspect. But I have to spend three or four dollars on a bag and I’ll typically only use one bag to the bed, as I’m filling it. It adds organic material, it helps get all of the microorganisms working to create a good soil and it really makes the whole process cheaper in the long run. Because I don’t have to fill the bed with these bags, I just use it to augment what I already have. I’m a big believer in growing plants in soil. And when I talk about soil, I mean the earth.

Bought garden soil

Everything that has taken millions of years to crumble and break down from the mountains and fill the space where we stand. I’m okay with adding organic materials to make the soil better so that the plants will grow better. But when you look at the “garden soil” that are in the bags that I showed earlier in the video, and you look at the ingredients in that “garden soil”, you’ll note that there’s no actual soil in those bags. It’s all organic material. It’s bark and coir and peat and compost. So what happens? Well, if you have a compost pile, and you may have seen this, you start with a big pile and it can lose 75 percent of its mass as it decomposes.

So if you’re buying that “garden soil” and filling a bed with it, it will decompose and it will drop in mass, up to 75 percent of that mass. So let’s say that I spent two hundred and seventy five dollars to fill this bed with that garden soil. A couple years later it’s going to have dropped substantially. Which means I need to add more of that garden soil just to keep the level where I want it to grow plants. Now that’s where we’re getting well over three hundred dollars to fill one of these beds. And it just keeps getting worse.

Adding to topsoil

And I might need to start adding some minerals to it, some rock dust, because there are no minerals that the plants are going to be able to use within that “garden soil”, which is really a soil-less mix. So by using what I dig up, by you using what you dig up, and then blending it within the beds, you’re really creating a much better environment for your plants. And in the long run, yes, you should be adding organic material regularly. But you’re not going to have to spend a lot of money on it because you can use your grass and your leaves on top as a mulch and just let that break down for free.

Now to be fully transparent, some of those soil-less garden soils on the back of bag will say that if you’re planning on using it to a depth usually more than three inches they recommend mixing it 50/50 with your own garden soil, the earth. That’s a great option and that ties in with exactly what I’ve been talking about. But remember a lot of those mixes are really nothing more than a blend of compost and a blend of peat. You can do the same thing yourself and save some money by just buying the peat and making your own compost, or finding bags that don’t really cost that much and doing the same thing.


Blending it just the same way that these big companies recommend you do it. When is the best time to start filling your beds? Well, I tend to think that late summer and early fall is really a good time to build and fill your raised beds because a lot of this organic material is not going to be available to plant roots right away. It needs to decompose a little bit. So by doing it in the fall you have all winter for the bio system to develop and the decomposition to happen. So in the spring when you start sowing seeds, this soil is nice and juicy and rich and healthy and ready to go.

This is the first bed that I filled using the methods that I described. Now, there’s one more step to the process, and it can be an important one. Remember the bottom half is all that free blend of soil and grass and branches and this top half is mostly what I purchased, the blend along with some compost that I added. I also added one more thing and that’s biochar. I like biochar. And for me it works in beds that are just starting to get established. If you have worm castings now’s the time to add worm castings.

What do you think?

If you have any of those organic materials that you really like or that you’ve heard really do a great job to improve the growth of plants, well incorporate it into the soil as part of the process of filling the beds with soil. That way when you put the plants in it’s all ready to go. If you have any comments or questions about filling your raised beds and how you can save some money, please just ask below. If you have any comments about this, by all means let me know those as well. I’d like to hear your experiences and raised bed ideas..

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