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All Things Garden,  Beginner Basics,  Compost

How to Fill Raised Garden Beds with Organic Soil

One of the most common gardening questions I get is: What kind of soil do you fill raised garden beds with? There are so many raised bed soil choices out there, it can feel confusing and overwhelming to figure out what’s best. It’s also pretty darn important to “get it right”, since soil health plays a HUGE and direct role in overall plant health and productivity.

Read along and learn how to fill raised garden beds with quality organic soil that is well-balanced, nutrient-rich, and microbially-active – so your plants will thrive! In this article I will share our raised bed soil “recipe” with bagged soil, bulk soil, compost, and amendment options along with tips on calculating soil volume and using hugelkultur to fill raised garden beds.

Getting Started with Raised Beds

Looking for tips on how to build a raised garden bed? Check out this post to learn how we build durable, attractive, long-lasting wood raised beds. The tutorial includes a step-by-step video and explores wood choices, bed sizing, location or placement, tips for gopher-proofing beds, non-toxic sealer, and other ways to make wood raised beds last longer.

Not feeling up to building your own raised beds? That’s okay! Gardener’s Supply Co has some really nice wood raised bed kits. We also love the sleek, high-quality, galvanized metal Birdies raised beds from Epic Gardening – and code “deannacat3” will save 5%!

Once you have your beds in place, it’s time to fill ’em up.

Filling the raised beds in our new garden space – with the assistance of a UTV since we had 19 beds to fill! Most of the other photos you’ll see throughout this post are from our old garden, where we did everything by shovel and wheelbarrow.

Investing in quality raised bed soil

Let’s set the record straight: “Dirt” is not soil! Soil is rich, full of nutrients, critters, microorganisms, and is biologically active! In contrast, dirt is usually devoid of all these things. Soil improves with time and age, as the soil food web blossoms. It is a living, breathing, dynamic ecosystem of its own.

No matter how much love, energy, or money you invest into your garden, if you have crummy soil, the result will be crummy plants. If you’ve gone through the effort to build or buy yourself some awesome raised garden beds, why skimp on the soil? However, the answer isn’t as simple as “go grab X brand of soil”. In my experience, not one soil is going to be perfect for growing vegetables on its own – bulk or bagged.

If you’re blessed with decent native soil, you can use some of that to fill your raised beds to offset cost (explored below). And if you already filled your raised garden beds with less-than-ideal soil, don’t fret! There are many ways to amend and improve existing soil, as discussed at the end of this post.

A diagram by Heidelberg Farms showing what the Soil Food Web looks like below ground. There are tree roots with compost and micro arthropods on the soil surface, with bacteria and fungi, mycorrhizae, and nematodes and protozoa below the soil surface, in and around the tree roots.
The Soil Food Web. Image Courtesy of Heidelberg Farms via Pinterest


Within the confines of a large container, raised bed soil needs are unique and slightly different than in-ground gardens. The goal is to create a raised bed soil mix that is fertile, rich in organic matter, holds moisture, but also has good drainage and plenty of air pockets using a combination of quality organic soil (bagged and/or bulk), compost, and an aeration additive.

Our raised bed soil recipe:

  • 40% soil (topsoil, loam, etc)
  • 40% well-aged compost
  • 20% aeration (e.g. sand, lava fines, perlite, pumice, cocoa coir, peat moss, and/or rice hulls)
  • Other amendments such as worm castings and mellow, slow-release organic fertilizers

Next, we’ll talk about each of these components in detail below. Note that the ratios are approximate; they don’t need to be exact. Also, this raised bed soil recipe can be applied to other types of container gardening, just scaled down. For example if you need to fill fabric grow bags, wine barrel planters, or pots.

Before soil shopping shopping, you’ll need first to calculate the volume of soil is needed to fill the raised garden bed(s).

Soil volume

Bags of garden soil come in measurements of cubic feet, usually in a range of 1 to 3 cubic-foot bags. Bulk soil purchased from a local landscape supply company will be in cubic yards. To calculate how much soil you need to fill a raised bed, begin by determining the volume of your bed in cubic feet. To do this, simply multiply the width by length by depth in feet (For example: 4’ x 8’ x 1.5′ = 48 cubic feet).

Now you have your total cubic feet, and can figure out how much bagged soil it would take to fill the bed. If you’re using bulk soil or compost too, you’ll need to calculate volume in cubic yards. To convert to cubic yards, simply multiply cubic feet by 0.037037 (or use this converter). Given the example of a 4×8′ by 1.5-foot deep bed used above, 48 x 0.037037 = 1.7 cubic yards of soil is needed to fill it.

If math isn’t your strong suit (or you’re just feeling lazy…. no shame!) here is a raised bed soil calculator that will do it all for you, in both cubic feet or yards.

Two hands cupping rich brown organic soil with a few red worms, hovering over a garden bed with leafy greens in the background below.

40% SOIL

Bulk vs bagged soil (or compost)

If you calculated that you need several yards of soil to fill your raised garden beds, you are not going to want to rely on bagged soil alone. The cost will add up quick! Look up local landscape supply companies and see what they offer in bulk – either for delivery or for pick-up, if you have a truck. For example, we often get bulk soil and compost delivered from Central Coast Landscaping or Mier Brothers here on the Central Coast. On the other hand, if you need to fill only one or two modest raised beds, purchasing bagged soil could be the way to go.

Bulk soil options

Bulk soil quality, composition and type will vary depending on your location. In our area, we’ve found varying grades of bulk soil including basic topsoil or “fill”, some premium container blends (similar to bagged soil), and a middle-of-the-road “planters mix” that is 2 parts top soil, 1 part compost and 1 part soil conditioner.

The composition of bulk soil will influence how much/what else to mix with it. For instance, if you all you can find is basic fill or topsoil, then you’ll want to follow the full raised bed soil recipe of 40% topsoil, 40% compost and 20% aeration to create a nice well-balanced soil. Or, use mediocre bulk soil as a “filler” at the bottom of deep raised beds, with a better soil on top.

Yet if you’re able to find premium raised bed soil in bulk, then it likely already contains a good amount of compost and aeration (sand, perlite, etc) so you can therefore scale back on those component of the recipe respectively. The landscape supplier should be able to provide details of the ingredients and make-up of the soils they offer!

An image of two very large mounds of soil on a driveway, on top of a blue tarp. It was a delivery of several yards of bulk soil and organic compost.
Years ago, one of the only bulk soil options we had was this “planters mix” (described above) along with a chunky shredded green waste “compost” blend. It honestly wasn’t the best stuff, but helped take up a lot of bulk in the bottom of our beds. We added higher quality bagged materials too.
In the years since, we’ve found a higher quality bulk “performance blend” soil that we used in our newest raised beds – along with 25% compost and about 5% lava cinders by volume (shown in the background).

Bagged soil options

Even if we use good bulk soil to fill the majority of our raised beds, we always add at least a few bags of high-quality organic bagged soil near the top. We’ve used a wide variety of bagged soils over the years, but tend to prefer the selections offered at our local garden centers and nurseries over big box stores. “Hydro” grow shops (those geared towards cannabis growers) usually have a great selection of premium soils too.

A few good options include Gardener & Bloom (G&B), E.B. Stone, Aurora/Roots Organics, Dr. Earth’s, and Fox Farms. Other cheaper or generic bagged soil can be used as filler towards the bottom of the bed, especially if you’re filling raised beds with bagged soil alone.

If possible, choose a few different bagged soils. Do not use “potting soil” only. It is light, fluffy, and will dry out quickly. In the photo below, you can see that we mix various types of bagged soil and conditioners. By combining a few different things, you’re getting a nice variety of composition and texture. Some are a little more woody, some more fluffy, some with perlite or pumice, some with or without added fertilizers.

An image of an almost empty wood raised bed. It is five foot by three feet, and 18 inches deep. Various bagged soils lay around the outside of it, waiting to be added.
This smaller raised bed was added to our existing garden, so we didn’t bother ordering bulk soil and filled it with a variety of bagged soils and compost instead, plus small lava rocks (explained more below).


Compost is organic matter that has been thoroughly broken down and decomposed into rich nutrient-dense plant food. It is a phenomenal soil conditioner, boosts the soil food web, and will make your garden shine! We try to add as much homemade compost from our worm bin or our large compost pile as possible. To learn about 6 different ways to compost at home, plus some general compost 101 do’s and don’ts, see this article.

Unfortunately, we usually cannot make quite enough homemade compost to meet all of our needs – especially for large projects like filling new raised garden beds with soil. So we do end up supplementing with organic bagged compost or bulk compost too.

Keep in mind that most bagged soils usually already have compost in them. So unless you’re using plain topsoil in your raised bed soil recipe, feel free to scale the “compost” ratio down to 10-30% (depending on the soil you’re using).

Compost options

Many bagged soil companies offer bagged compost products too. Again, these can be found at your local garden center or hydroponics grow shops. You should also be able to find compost locally in bulk, which is usually derived from green waste or possibly composted food waste. The bulk compost we purchase is made from local green waste and is OMRI-certified for organic gardening.

Our favorite bagged compost is Malibu Compost Biodynamic Blend, or just referred to as “Bu’s”. It is made from aged, composted cow manure from certified organic dairy farms. They use biodynamic practices. The compost ingredients include organic aged manure, straw, vineyard wood chips, plus yarrow, chamomile, valerian, stinging nettle, dandelion, and oak bark! It is not uncommon to rip open a bag to dozens of happy worms squirming around in there. However, please note that Bu’s compost is quite rich, so they recommend mixing only 25% of their compost to your soil blend.

Unfortunately, Bu’s is primarily available on the West Coast. If you live in the Northeast, Coast of Maine makes a similar product. I’m sure there are many more companies out there, all over the U.S. Leave a comment if you are aware of a good local product like this in your area!

A photo of a bag of compost, by Malibu Compost. It is sitting on the gravel, leaning up against a half-filled raised bed behind it.
We love Bu’s. People hear me talking about this on Instagram and often think I am talking about how much we love “booze”… 😂

Manure versus Compost

Note that fresh manure is very different from compost. Yes, Bu’s compost starts with manure, but it aged and composted over time to become a more mild, balanced product. Fresh manure that hasn’t been properly aged is very high in nitrogen and can burn your plants. Therefore, avoid adding fresh animal manure to your garden. I am also a little leery of animal manures that are not from certified organic operations (antibiotics, pesticides, hormones, GMOs, ya know…) or have an otherwise unknown source.

Worm castings

Last but certainly not least, worm castings (aka worm poop!) are compost too. Worm castings are so good for your plants, they’re referred to as “black gold”. Worm castings offer gentle, slow-release fertilizer as well as improve soil structure, microbe activity, water retention, and drainage.

I highly recommend keeping a worm bin at home! It is a terrific way to divert food waste from the landfill, and up-cycle that “waste” into an incredibly valuable product for your garden or house plants. Worm bins are inexpensive, easy to maintain, and no, they do not smell bad. Learn how to set up and maintain a super simple worm bin here!

If you aren’t up for keeping your own worm bin, you could purchase finished worm castings and add at least a small mount to each bed. We can usually find bags of G&B Organics Worm Gro locally, or you could pick up some worm castings online here, or from Uncle Jim’s Worm Farm.

A hand holding a handful of rich looking soil, which is actually worm castings. A few red worms are in with the worm castings. In the background, there is a whole tub of worm castings,
A little tub of screened worm castings or “black gold” being added to the new raised bed, from our worm bin. As you can see, a few friends came along for the party!


Nearly as important as the compost component, an aeration addition is key to healthy soil. This could include lava rock, pumice, or perlite. Coarse sand also promotes aeration and drainage, but not quite as effectively as the others.

Note: Like compost, a lot of bagged soil mixes already contain some perlite, pumice, peat moss, or rice hulls. Those are all forms of “aeration”, and are adding to our target total. So if you use primarily bagged mixes, read the ingredient list. If they contain those things, you can go lighter on adding additional aeration (e.g. perhaps only 10% extra, if any).

Benefits of lava rock, pumice or other aeration in raised bed soil

Why add aeration material to raised bed soil? Well, as we talked about, soil is full of living things – including beneficial microbes, nematodes, worms, protozoa, fungi, and more – and those friends need air to survive. Even more, plant roots need air to thrive too! Did you know plants breathe through their roots just as much as they do through leaves? That’s why it’s important to not overwater, and always provide drainage holes in pots. Otherwise, the plants will drown!

An aeration additive doesn’t only provide air. Their presence promotes drainage and prevents the soil from over-compacting. It may seem counter-intuitive, but absorbent materials like lava rock and pumice also increases moisture retention at the same time. They create air pockets for drainage, but also hold water within themselves like a sponge, helping to maintain evenly moist raised bed soil for a longer period of time between watering. Like many things in gardening, it’s all about balance.

Lava Rock

For the aeration portion of our raised bed soil recipe, we have come to love volcanic rock. It is also called “lava cinders” and is frequently used in aquaponics. We get the small 3/8 inch to quarter-inch size. Don’t use larger chunks! Lava rock is full of pores, that not only promote aeration and drainage, but are also the perfect habitat for beneficial microbes to grow. They don’t float to the soil surface like white bits of perlite do, and are generally more affordable than pumice.

Our local landscape supply company carries volcanic rock both in bulk and in half cubic-foot bags. For any Central Coast locals, I am talking about AirVol Block in San Luis Obispo. This is where we get a lot of our hardscaping materials like stone blocks, green rock gravel, cobblestones, and pathway pavers too.

If you can’t find volcanic rock, use small perlite or pumice. Availability of all these products will vary depending on your location.

A hand holding small red lava rock pieces, that are being added to the new raised bed.
3/8″ lava rock – added for aeration, drainage, moisture retention, and surface area for microbial life!


Another thing that will help with aeration is… my favorite: worms!

Did you know that Cornell University refers to worms as “living soil amendments”? Worms play a vital role in the overall health of organic soil, as part of the soil food web. By simply being present and doing their wormy thing, they continually aerate, nourish, and improve soil structure! Furthermore, as they cruise around, they break up the soil. This in turn improves drainage, increases moisture retention and oxygen flow to plant root systems – all very good things!

“Worms feed on plant debris (dead roots, leaves, grasses, manure) and soil. Their digestive system concentrates the organic and mineral constituents in the food they eat, so their casts are richer in available nutrients than the soil around them. Nitrogen in the casts is readily available to plants. Worm bodies decompose rapidly, further contributing to the nitrogen content of soil.”

NSW Government Agriculture

Adding worms to raised garden beds

As worm castings are added into each of our raised beds, a few red wiggler compost worms (and their cocoons or babies) usually hitch a ride too! Now they’ve been introduced into the bed, and will continue to populate. Red wigglers are fairly small worms, reproduce quickly, and break down food matter fast, thus creating castings faster. They’re perfect in a worm bin, and good in the garden too! However, red wigglers generally like to stay near the soil surface. On the other hand, earthworms like European Nightcrawlers like to dive deeper in the soil to do all their good work. We add some of those big bad boys to our garden too!

Two hands held together, cupping a large pile of european nightcrawler earth worms. The hands are poised over a garden space
European Nightcrawlers from Uncle Jim’s Worm Farm, about to to be added to the soil around our fruit trees – where the soil is compacted. A few got added to each bed too!

Please note: Most earthworms are not native species to North America. They are excellent additions to your garden, but some can disrupt native ecosystems (such as forests) if they’re introduced elsewhere. This is particularly a concern with a dense population of European nightcrawlers.

Thus, please make responsible decisions when adding worms to your soil, depending on your garden (e.g. does it abut a woodland?) Within the confines of urban or suburban gardens, their presence is generally welcome and helpful! The bottom of our raised beds are blocked off with landscape fabric, so they can’t easily get into the native soil.


Now that we have a better idea of the types of materials we want to add to our raised beds, it is time to fill them up!  Yep, our beds are 100% full of all this good stuff. Aside from sometimes adding bulk soil to the bottom of our deepest beds, there is no other “fillers” at the bottom. Just how the roots like it!

The goal is to get all of these materials evenly mixed, as much as possible. We’ll generally add them in “lasagna layers”, mixing as we go. For example, add several inches of bulk soil or bagged soil, a good layer of compost, a couple inches of volcanic rock, and mix. With that, the bed may only be about quarter full. Repeat with more layers of each, mix. Continue this process until the bed is full.

Fill garden beds all the way up – within a couple inches of the top! When you first water the bed, it will compact and sink down a little. Depending on how much it sinks, you may want to top it off with another layer of compost or soil. Filling shallow raised garden beds (e.g. 1 foot deep or less) as full as possible is especially important. Empty space in the left bed is wasted space for happy plant roots

An image of a newly built redwood raised bed, only about half full at this time. In the bed, there is a combination of soil and compost, with some red volcanic rock on top, about to be mixed and then continued to be filled.
In the past, we’d add alternating wheelbarrows or bags of soil to create a “lasagna layer” of soil, compost, and volcanic rock, mixing in the layers as we go until it’s full. Back in the day (in our smaller garden) we did all our bed-filling by wheelbarrow and shovel, even when we did order in bulk.
When creating our new garden, we rented a skid steer (tractor bucket loader) to scoop up the bulk soil and compost from the main pile in the driveway, load it into the back of our UTV, then drove it to the raised bed area to dump into each bed. We pre-mixed the soil, compost, and lava rocks in the UTV first by loading the material in alternating scoops, and then mixed it further by shovel as it was added to the bed.

What About Hugelkultur?

To offset cost and take up some space at the bottom of a deep empty bed (e.g. two feet or deeper), you could choose to add some small logs, branches, leaves, mulch, pine needles, or other woody organic matter, and then add at least a foot of soil and compost on top. The woody debris eventually breaks down to feed the soil as a carbon source over time.

This practice is called Hugelkultur. Learn hugelkultur pros and cons, best practices and materials to use, and how to make a hugelkultur garden bed here. However, I do not recommend adding non-organic matter such as rocks, plastic bottles, sytrofoam, or other random materials to take up space in your bed. I also don’t recommend using hugelkultur in shallow raised garden beds (1 foot deep or less).

Raised Bed Soil Fertilizers

Most “virgin” soil (especially topsoil) will need some amending with mild, balanced, slow-release fertilizers to keep your plants healthy, happy, and productive! This is true whether it comes trucked in bulk or from a bag.

If you filled your raised garden bed primarily with high-quality organic bagged soils and compost, you can go pretty light on the fertilizer for the first growing season. Those bags usually contain pre-amended soil with light fertilizer and some compost added. But as the next growing season comes around, you’ll want to start implementing a fertilizer routine for your raised garden beds. As your plants grow, they will use up a lot of the available nutrients in the soil.  If you fail to amend the beds in preparation for the new crops, you set them up to flounder and starve!

On the flip side, if you started primarily with bulk soil and compost from a local landscape company, you’ll most definitely want to add fertilizer from the start. That is, unless they say that it’s already amended. Though I don’t think that is common practice for most bulk material.  

Organic Soil Amendment Options

Every gardener has their own preferences for fertilizers and amendments. Let me tell you about ours, and then you can make you own decisions and research further from there!

We don’t ever use the “heavy-hitter” fertilizers, like blood meal, bone meal, or feather meal. I call them heavy-hitters because they’re usually really high in one macronutrient or another – nitrogen, phosphorus, or potassium (NPK). While all those nutrients are essential, we don’t feel the need to dose our plants heavily with animal byproducts. Due to their strength, there is an increased risk for shocking and “burning” your plants. Between the compost, worm castings, aerated compost tea, and other more natural, mild amendments and practices we feed our soil, we just don’t find the former to be necessary!

Let’s talk about what we DO use.

Mellow Meals

We prefer to add mellow, balanced, slow-release, plant-based fertilizers to our raised bed soil. Down-To-Earth brand has been our go-to for the past several years, though we use other brands at times too. The main products we use are kelp meal, neem meal, alfalfa meal, or this vegan all-purpose fertilizer. They’re all OMRI-certified for organic gardening.

We sprinkle in these mellow meals on top of the soil, lightly scratching and working them in to the top few inches. We do this a couple times per year, usually between switching out crops in beds. Keep in mind we garden year-round here, so your fertilizing schedule may vary. I always suggest going a little lighter than the instructions on the box. You don’t want to accidentally “burn” the plants! Even these gentler options do pose some risk of that, if you overdo it. They all have their different benefits so we usually mix a few of them. If you were to start with just one, go for the all-purpose stuff.

Sprinkling in a combination of kelp, alfalfa and neem meals to the top of the soil once the raised bed is full.  This will be scratched into the top few inches of the soil, and watered in.  We also added some rock dust here, and earlier when the bed was only half-full.
Sprinkling in a combination of kelp, alfalfa and neem meals to the top of the soil once the raised bed is full. This will be scratched into the top few inches of the soil, and watered in. We also added some rock dust here, and earlier when the bed was only half-full.

Rock Dust

One optional amendment we always add to our garden is basalt rock dust. We add rock dust when filling new raised beds with soil, or when planting trees or shrubs in our native soil. It is slow-release and cannot burn or harm plants like fertilizer can.

Rock dust comes from volcanic ash. It is low in macronutrients, but absolutely loaded with trace minerals. It helps increase nutrient uptake by plants, increases crop yields, improves plant immunity, boosts pest resistance, and generally enhances soil and plant health. Check out for more information and research about rock dust!


Finally, don’t forget to cover the soil with a couple inches of mulch. Mulch protects and improves raised bed soil by reducing evaporation, suppressing weeds, and buffering the soil (and plant roots) from temperature swings. We typically use a woody compost as mulch. Learn more about mulching best practices and pros and cons of 8 popular mulch options here, including bark or wood chips, straw, compost, and more.

Full, freshly mulched beds in our old garden


Do you have raised beds that are already full of soil that you aren’t very happy with? Or more like, that your plants don’t seem very happy with? It’s okay! In fact, we have been in this boat before too. Do not feel the need to go dig out all your soil and start over. There is hope!

Before you consider replacing your raised bed soil, try amending it first using some of the materials we’ve discussed already.

If your plants are sad and small, have you been fertilizing them adequately? Is your soil too compact? Try to mix in some aeration additive.  Does it seem like the soil drains too quickly, or dries out to quickly? Add compost and worm castings! That, along with watering with aerated compost tea, will increase the microbial life in your soil. For better moisture retention, drainage, and “fluff”, peat moss or coco coir could also be mixed in. Note that coco coir is the more sustainable option of the two.

First, try those measures for a season and see if there is noticeable improvement. I really think there should be. If not? Next, consider taking out at least a portion of the old soil and replacing with the types of things discussed in this post.

The final raised garden bed for this example, now completely full of soil, compost, and aeration additions. It is being watered, with drips of water running down the side of the bed, and a rainbow has appeared in the water spray.
The final full bed. Make sure to give it some water to get everything happy, and to get those microbes kicking!

And that’s how we fill new raised garden beds with soil!

I hope that was helpful! Going forward, we do plenty of other things to feed our soil too – such as using mycorrhizae during transplanting. Or, routinely watering with actively aerated compost tea (AACT). Check out this article all about how we routinely amend and prepare our raised bed soil between planting seasons. Otherwise, thanks so much for reading. Feel free to ask questions in the comments below. Also spread the soil love by sharing this post if you found it useful!

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  • Jason

    Hi folks!

    I’ve built some 24 inch deep beds and filled them thusly: About 8 inches of wood/leaves, 10 or so inches of spent mushroom compost (we have a local business that gives it away), and finished the top with standard triple mix soil. The spent mushroom compost is horse and chicken manure, straw, and gypsum.

    Do you think this is a decent starting point for a Zone 6 garden? I’m planning on planting cherry tomatoes, peppers, garlic, herbs, and one dedicated pollinator garden with native flowers.

    • Aaron (Mr. DeannaCat)

      Hi Jason, were you going to mix the soil and compost together or are you leaving them layered like lasagna? Seems like it should work out as long as the soil isn’t too rich with compost.

      • Jason

        It’s mostly lasagna now. I was thinking that the layers + time (August 22 – Spring 23) would let some natural biology do its work (with mulched leaves on top). Do you think I should blend it?

        • Aaron (Mr. DeannaCat)

          It’s hard to say but we usually like to keep the compost to around 25-30% of our total soil volume, it seems like you may have a tad more than that. However, I think leaving it in layers is fine, especially so since you are topping the bed with mulched leaves. You could always throw in some winter or early spring cover crop to boost the microbes in your soil which will give everything a jump start for your summer garden. You should be good to go and have fun growing!

        • Day

          Hi I’m wondering how many bags of Bu’s compost do you use for a 4×6 bed? I’m trying to calculate how much soil compost snd aeration I need to fill 8 beds and my numbers seem crazy huge. It’s saying I need 137 bags of compost (40%). Does that seem about accurate to what you guys have done to fill your new beds?

          • Aaron (Mr. DeannaCat)

            Hi Day, we did a collaboration with Malibu Compost for our new garden area so we were able to get the compost in 2 yard totes. We also used a ratio of about 70% soil 25% compost and roughly 5% or less small volcanic lava cinders. When filling larger raised beds in the past, it was not economically viable to use all Malibu compost so we offset that with lower quality compost that we could get in larger amounts but we would usually add and mix in a bag or two of Malibu compost to the top portion of the raised bed. I think you can get by with a smaller percentage of compost, similar to what we used in our new space, I would also check locally to see if you have any bulk compost companies nearby or at the very least, bulk landscape supply companies that sell soil and compost by the yard. We can get a pretty good “performance blend” soil from a company around here but the compost they typically have is pretty barky and not very well broken down. In time, it will break down further into organic matter and once worms and moisture are present, it will start to become alive with microbes and other life.

            So in all, if you are set on using Malibu Compost, I would look into getting one of their 2 yard totes as it should be a lot cheaper than purchasing it by the bag and use closer to 25% compost to your total soil makeup. If you have other compost available to you that may not be as good, you can still use it and mix in a couple bags of Malibu compost towards the top portion of your beds. If you are in the PNW, Oly Mountain Fish Compost may be a better option or if on the East Coast, Coast of Maine Lobster Compost. And again, you may have a really great compost producer in your area but that can vary wildly depending on where you are located. Hope that helps and good luck!

  • Megan

    Hi Im a local. In AG. Im wondering where you buy your planters mix from? I need to buy in bulk as I’m filling 5 large raided garden beds. Thank you

    • Aaron (Mr. DeannaCat)

      Hi Megan, we got the “performance blend” bulk soil from Central Coast Landscaping, we would recommend amending it with 20-25% with quality compost such as the bulk compost from Cal Poly or something similar. Hope that helps and good luck filling your raised beds!

  • cornelia

    Hi; great website! Have a question: can I replace the cinder/lava rock with turface MVP in grow bags mix? what will be the ratio? I cannot find the 3/8 lava rocks here in kentucky. Thank you

    • Aaron (Mr. DeannaCat)

      Hi Cornelia, you can use perlite if you would like as an alternative but you don’t need to add any extra of either as long as your main soil mix has decent aeration. We can get soil by the yard from a local landscape supply company that is called “performance blend”, we use about 70% of that mix with close to 30% compost and it works out great. Hope that helps and good luck!

  • Lisa

    Hi guys my husband and I are new to growing. We live in Arizona and we received 3 days of nonstop Monsoon rain a few weeks ago. Since then our 3 tall photos which recently began flowering have started yellowing on the bottom part of the plant. I am also seeing what may be the start of a magnesium deficiency. We followed your ROLS recipe and we also grow in 25 gallon fabric grow bags. This week they got a dose of neem/kelp ( top dress). Can you suggest anything that i can try for the magnesium? I have been reading that if left unattended it could spiral quickly. Thank you.

    • Aaron (Mr. DeannaCat)

      Hi Lisa, kelp meal is a great amendment and one that we will use throughout the growing season as a top dress or as a tea. Have you been regularly feeding your plants via top dressing or teas throughout their growth so far? It is great that you just gave your girls a top dress, however, that is something that will be broken down slowly so a tea may have quicker effects. I would make a kelp tea to water your plants with and that should be absorbed more quickly than your top dress. Do you have access to high quality worm castings or compost? If so, another option would be to make a compost tea and water your plants thoroughly with that. If either option is viable, I would use compost tea first and then make kelp tea for later in the week. As in, if you are watering 3 times a week, give the compost tea on Monday and the kelp tea on Friday. I am also not sure how worried I would be about the yellowing leaves as that usually happens from the bottom of the plant first as it ages. As the plant continues to flower, it will put more energy into its flowers at the expense of its leaves, although all strains are different and some stay green longer while others will start to fade sooner. Hope that helps and good luck!

  • Cathy

    We are building elevated gardening beds since we are on a slope. What material should we line our beds with to keep the wood from rotting. I’m particularly concerned about anything leeching into the vegetables. What would your suggestions be

    • Aaron (Mr. DeannaCat)

      Hi Cathy, we don’t line our beds with anything aside from commercial grade landscape fabric. Your beds should still last close to 10 years if you use redwood or cedar so I wouldn’t worry about them rotting. Hope that helps and good luck!

      • Eduardo

        Hello AARON, thank you for the excellent material you share on your website. I just constructed my raised beds with treated pine wood but now I’m in search of good material to protect the soil from those wood chemicals. Thank you for your time.

  • Alyssa

    Hi! I’m wondering about what ratios of mellow meals you use. I bought Down-To-Earth crab meal, alfalfa meal, and kelp meal. I’m planning to add a mixture of all three to my beds. When mixing these meals, do you use the amounts per cu/ft recommended on the box for each one? Or do you use less of each since you are combining them? I don’t want to burn my plants by going overboard. Thanks for all the information you provide!

    • Aaron (Mr. DeannaCat)

      Hi Alyssa, we usually determine the amount by the square footage of the raised bed and we usually apply less than what it says on the package. I think on an 8×4 (32 square feet) foot bed when amending between seasons I would add about 1.5-2 cups kelp meal, 2-3 cups crab meal, and 2 cups alfalfa meal. The alfalfa is the one amendment that is “hot” and can burn your plants so it is best to go easy on that one compared to the others. During the growing season we usually add equal amounts of each amendment and top dress tomato plants with 1/4 to 1/2 cup of the mixed amendment and an 1/8th cup mixed amendments for peppers, eggplant, and squash each month. Hope that is enough to get you started and happy gardening!

  • mike barnett

    We built some elevated beds, so they do not sit on the ground. I am assuming the 40% soil, 40% compost, 20% aeration applies, but when you look at a product like Kellogg Raised Bed and Garden Mix, where does that fit in the ratio?

    • Aaron (Mr. DeannaCat)

      Hi Mike, I would consider that soil mix a combo of soil and compost although it does have some bits of perlite as well. If Kellogg is your main option, I would also add some of their Patio Plus as well as their Amend lines to add a bit more richness to your mix. Gardner and Bloome is Kellogg’s organic option and one that I would try and locate if it’s available in your area. We will usually use a combination of G&B’s Raised Bed Mix, Potting Mix, Planting Mix, Harvest Supreme, and/or Soil Conditioner as mulch. Hope that helps and good luck!

        • Aaron (Mr. DeannaCat)

          Hi Riley, yes it will help make your soil more light and fluffy which will create more pockets for air, it will also help retain moisture as well. If you are mixing it into a combination of potting soil and compost, maybe add 10-20% of the total volume of soil needed. Hope that helps and good luck!

        • Barb

          OMG, thank you so much for all your incredible, easy to understand and useful information. I am so glad I came across your website. Working on my garden beds now, hoping to get my act together to make GF sourdough bread!

          • Aaron (Mr. DeannaCat)

            Good luck on those garden beds Barb and baking sourdough is a lot of fun so hopefully you get to it before too long!

  • Paul Sapienza

    I need to fill raised beds that are 32 inches deep (2 feet 8 inches) 8 feet long and 4 feet wide
    Should I use the entire depth with the 40-40-20% ratio or should I fill the bottom with dirt from my backyard to a certain depth and then add the ratio mix

    • Aaron (Mr. DeannaCat)

      Hello Paul, those are some deep beds! We usually fill the bottom of extra deep beds with soil that we can get in bulk that is usually not as great to grow directly in but with time it will become just as rich as the rest of the bed. So adding soil from your yard is fine as long as there aren’t too many pests, disease, or anything else to worry about. Another option if you have fallen trees or logs on your property is to fill the bottom with branches, logs, leaves, etc. as it will take up space and will break down with time turning into organic matter. Hope that helps and good luck!

  • Lynn Baden

    Hi. Love your website. I am gardening vegetables for the first time this year and bought the metal raised beds. I have purchased my soil and before I fill the beds, I have a question. Do you put any type of product on the ground prior to filling the bed? I was thinking specifically about garden cloth. Any thoughts?

    • Aaron (Mr. DeannaCat)

      Hello Lynn, congrats on getting into gardening for the first time. It really turns into a healthy hobby and lifestyle. As far as your question is concerned, it really depends on what is growing in the ground where you are going placed the raised beds. If you just have basic grass and there are no pesky weeds that may work their way into your beds, using a few layers of cardboard on the bottom of the beds will help suppress grass and any mild weed activity. If you have weeds that like to travel and invade most things, cutting out an area for your beds and placing contractor weed fabric over the top and affixing it with landscape staples would be recommended. You can then either lay mulch or gravel around the surrounding beds to help tie everything together. Check out our How to Kill or Remove Grass (& Grow Food Not Lawns!) article for more ideas. Hope that helps and good luck to you. Let us know if you have any other questions.

  • Jeni

    Hi there! Brand new to gardening. We just built raised beds for vegetables and flowers and had a bulk order of “garden blend soil” dropped off. It is quite smelly of cow manure and I’m worried it is too fresh/not aged and perhaps too high a percentage of compost to sand and soil. Any suggestions on how to work with it? I was thinking of trying to blend it with the existing dirt underneath to tone it down a bit. In Vancouver BC where the earth we’re digging into seems quite rich as is (we dug up grass before putting down our cedar beds). Thanks for your help!

    • Aaron (Mr. DeannaCat)

      Hello Jeni, congrats on getting into gardening, living in Vancouver BC that is a great idea as it is quite a green and beautiful place! It is really hard to tell how “hot” the soil is or not without knowing the product firsthand. You could double check with the company who sells the product and inquire about the exact ingredients and if the manure has been composted long enough. Although your idea of mixing it partway with your native soil sounds like an excellent idea as the native soil is most likely very rich and alive. For what it’s worth, a lot of garden soil, especially bagged soil can have a bit of a smell to it with no negative effect on plants. Good luck and happy gardening!

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