3 Raised Bed Soil Mixes Compared

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Updated October 2021

Have you ever wondered what kind of raised bed soil mix is the best?

I have been growing in raised beds from the very beginning of my garden journey. In the early years, I used native soil from my property to fill them.

But when I needed to find soil outside my property for three new raised beds, I decided to conduct an experiment. I tested three different raised bed soil mixes and today I’m sharing the results of my year-long test.

(Click below to listen to my discussion on the Beginner’s Garden Podcast, or continue reading.)

*links below may contain affiliate links

3 Types of Raised Bed Soil Combinations

When deciding which raised bed soil combinations I wanted to test, I chose two common mixes that many gardeners use that include topsoil and/or compost I bought in bulk from my local landscaping company.

In the third bed I used organic bagged soil only, purchased from Home Depot. Because many gardeners can’t purchase ingredients in bulk, I wanted to test this option to see how it compared.

Here are the three raised bed soil blends I tested:

Mel’s Mix

I first chose Mel’s Mix from Mel Bartholomew’s book Square Foot Gardening. This mix consists of:

The compost is the key here. In Square Foot Gardening, Mel recommends using compost from as many sources as possible. (Just an anecdotal observation here… those to whom I’ve spoken over the years who have had poor results using Mel’s Mix seem to have had poor quality compost or compost from just one source.)

To achieve as diverse of compost blend as I could, I used bulk compost (compost I bought from a local landscaping company), worm castings, and chicken manure from my own chickens.

Mel's Mix
Mel’s Mix in Raised Bed #1

Perfect Raised Bed Soil Recipe

The second mix I tested is known as the “Perfect Soil Recipe” as recommended by Joe Lamp’l. It consisted of:

  • 50% topsoil
  • 30% compost
  • 20% other organic matter.

Joe has many different suggestions on sources of organic matter. I used homemade compost, chicken manure, and worm castings.

Perfect Soil Recipe
“Perfect Soil Recipe” for Raised Bed #2: topsoil, bulk compost, and homemade compost mixed with worm castings and composted chicken manure

Bagged Soil for Raised Beds

In my third bed, I chose a blend of bagged soil. I purchased:

  • four bags (8 total cubic feet) of organic garden soil
  • two bags (2 total cubic feet) of organic garden soil “plus” (with extra organic fertilizers)
  • two 40-lb. bags of topsoil
  • three cups of worm castings.

Most of this I got at Home Depot, but I’ve also seen it in other garden centers.

Method of Testing Raised Bed Soil Mix

In these three raised beds, I planted Roma tomatoes — three per 3’x6′ bed. Each tomato plant I had grown from seed indoors and I planted all nine of them at the same time.

Planting Tomatoes in 3 raised bed soil mixes
From the nearest bed to the furthest: Mel’s Mix, Joe’s Perfect Soil Recipe, and Bagged soil

First Impressions

Mel’s Mix

Planting in Mel’s Mix was a dream. It was light and fluffy and wonderful to work with. No matter how much rain we got (and we had a LOT of rain) it never got waterlogged nor had drainage problems. I had no weeds in the first month and my tomatoes started out incredibly healthy.

But the drawback of Mel’s Mix? The ingredients were the most expensive to purchase.

mel's mix for raised bed tomatoes
Mel’s Mix

Perfect Soil Recipe

The bed with the “perfect soil recipe” didn’t start out as great as Mel’s Mix. But, I have to consider a few extraneous factors.

First, we had a record spring rainfall year in 2019, and the topsoil I purchased for the “perfect soil recipe” seemed to contain a lot more clay than I have seen with other topsoil mixes.

In hindsight, I realized that this particular topsoil is sourced from a river bottom. So while I’m sure it contained high amounts of nutrients, it was pretty dense. It certainly had a different color and texture compared to bagged topsoil mixes (like the one I used in the bed with the bagged soil).

Because of this (from my observations), this bed didn’t drain well and seemed to compact after the heavy rains. Initially, my tomato plants struggled and were smaller than those in Mel’s Mix.

I also had more weeds in this soil than in the Mel’s Mix, though that was probably due to the higher percentage of my homemade compost.

Bagged Soil Mix

The bagged soil mix was extremely easy to put together and, like Mel’s Mix, was a dream to plant in. It did not compact or have drainage issues in the heavy rain. But, the tomato plants from the very beginning barely grew, something that continued to be an issue for this bed.

After 1 Month

The tomatoes in Mel’s Mix grew vibrantly and were strong with tender leaves. Weeds did start to develop, but they weren’t too bad.

Mel's Mix tomatoes in raised bed

The tomatoes didn’t grow quite as well in the “perfect soil recipe,” but they did grow consistently.

topsoil raised bed compost mix
Perfect Soil Recipe

The biggest shock was with the tomatoes in the bagged soil mix. These were not healthy at all. Many of the leaves were very yellow and the plants itself appeared severely stunted. I had planned to keep everything the same in all 3 beds. However, these looked so unhealthy that I started watering them with fish emulsion to try to save them because I feared I would lose them.

bagged garden soil for tomatoes
Bagged Garden Soil

Rest of the Season

The tomatoes in Mel’s Mix continued to be strong and vibrant. I expected them to slow in growth due to the high concentration of peat moss.

When I’ve used potting soil with a lot of peat moss in the past, it tends to repel water as it dries out. Surprisingly, this did not happen. I did keep consistent drip irrigation on the beds during the dry summer, and this mix never did compact or dry out as I would have expected.

mel's mix tomato

The tomatoes in the Perfect Soil Recipe bed ended up almost catching up with the Mel’s Mix plants. I think this was probably because the rain let up and the plants were no longer drowning.

perfect soil mix recipe

While the tomatoes in Mel’s Mix and the “perfect soil recipe” ended up performing well, I can’t say the same about the tomatoes in the bagged soil mix. Although they didn’t die as I had feared, they never rebounded and never looked healthy.

bagged garden soil

Total Yield Comparison Between Raised Bed Soil Mixes

The biggest indicator of the success of any raised bed soil mix is the total yield, and this I measured meticulously throughout the garden season.

As mentioned previously, I grew Roma tomatoes in all of these beds. As a determinant variety that bears all at once, I could weigh the harvest within a short window of time before pulling them up and planting a second crop to test.

Below are the yield results from these Roma tomatoes in each mix, compared with Romas I also planted in my in-ground garden. I must point out, in this particular year, my tomato yields were lower overall, probably due to the excessive rainfall and my battle with early blight. Still, you can see the marked difference between the beds.

  1. Mel’s mix: 7 lbs/plant
  2. Perfect soil recipe: 5.3 lbs/plant
  3. Bagged soil: 1.34 lbs/plant
  4. In-ground Roma tomatoes: 2.59 lbs/plant
tomato harvest next to raised bed

You can see that my plants in Mel’s Mix did much better than any other soil, and the bagged soil mix was quite disappointing.

Also of note: the Roma tomatoes in the ground suffered more from early blight, and I also planted them slightly closer to one another. Still, this result remains consistent for my garden — tomatoes in raised beds generally out-perform their counterparts in the ground soil.

Fall Broccoli in Different Raised Bed Mixes

As you see above, my first experiment tested the performance of Roma tomatoes in the summer. For my second test, I planted broccoli. The results of that test differed slightly.

In September, I planted broccoli I started from seed indoors both in the Mel’s Mix and the Perfect Soil Recipe beds. I didn’t have enough seedlings to plant them in the bagged soil bed. I ended up buying transplants from a garden center and planted them in the bagged soil bed about a month later.

Whatever difference I saw between Mel’s Mix and the Perfect Soil Recipe in the early growth of Roma tomatoes disappeared in the fall-planted broccoli. Both beds performed extremely well and produced lush, vibrant broccoli — the largest I’d ever grown.

broccoli in raised bed soil mixes

I did have a peculiar fall, however. A record-October heatwave prevented this lush broccoli from forming heads, and an early freeze in November damaged the plants severely. Because of this, I barely harvested any heads from this group.

As a contrast, the smaller plants in the bagged soil mix (because I planted them a month later), withstood the cold snap and went on to produce full, large broccoli heads. Though the plants themselves never grew at the rate that those in the first two mixes did, they produced well.

Soil Test Results from 3 Raised Bed Soil Mixes

At this point, my only conclusions could be drawn from observing the growth of two crops — tomatoes and broccoli. But what would a soil test reveal about the differences between these three raised bed soil mixes?

Prior to the broccoli planting, I sent off soil samples to my local cooperative extension service. Here were the highlights of the differences between the soil test results:

  1. Mel’s Mix: Ph 5.6 (not surprising because peat moss is naturally acidic). It tested “above optimum” on phosphorus, potassium, and zinc, and all other micronutrients tested.
  2. Perfect Soil Recipe: Ph 6.8 which about perfect for most vegetables, but perhaps a little on the high side for tomatoes. This recipe showed above optimum levels on phosphorus, potassium, and zinc, and all other micronutrients. Of special note, these levels were also above Mel’s Mix in each. Plus, it had almost double the calcium of Mel’s Mix.
  3. Bagged Soil Mix: Ph 7.5 — this is high for most vegetables, especially tomatoes. It was also above optimum on phosphorus, potassium, and zinc, but the levels were erratic on some of the micronutrients. I also noted a very high amount of sulfate compared to the other two and very high on calcium.
free garden printables

Speculations in Differences Between Raised Bed Soil Mixes

I’m not a soil scientist, and I can’t tell you all the “whys” behind what I found from my test. But between the soil test and my own observations, I have some thoughts about the differences in the soil mixes.

Conclusions on Mel’s Mix

I think that Mel’s Mix performed well because our spring was so wet and the peat moss didn’t have a chance to dry out. Instead, the drainage capacity of the peat moss proved helpful in our rainy spring.

Conclusions on the Perfect Soil Recipe

I believe the Perfect Soil Recipe started slowly because of the amount of rain and because of the high amount of clay in the topsoil I purchased. If I had obtained topsoil with less clay content, I imagine this blend would have rivaled Mel’s Mix or even surpassed it.

Conclusions on Bagged Soil Blend

The bagged mix blend is a mystery to me because this brand was recommended by several trusted gardening friends, and most of those I’ve asked have had a much better experience with bagged soil. This is also why I am not disclosing the brand — I do not believe my experience is necessarily indicative of all of this brand’s products.

So, if so many people get great results with bagged soil (even organic bagged soil like mine), why were my results so terrible? I have a few theories.

Why bagged soil didn’t perform well in my raised bed:

It seemed like these bags of soil had a lot of tree bark and perhaps it hadn’t broken down enough. Instead, as it continued to break down it tied up nitrogen my tomatoes desperately needed.

I also wonder if the soil was missing some of the micro-organisms and soil life that is present in both native soil and compost. Perhaps this was why it eventually corrected itself with the broccoli — the soil life had a chance to return.

Third — and perhaps most obvious — was the high Ph. Broccoli can tolerate higher pH than tomatoes can.

And although I can’t tell you which of my theories is correct — maybe all three played a role — I can tell you, I learned several lessons from this experience with bagged soil.

Biggest Lessons

After having tested these three blends of raised bed soil mix, what will I do with future beds?

  1. Although Mel’s Mix performed better than I expected, it’s not my choice because of the expense. If I were to only build one small raised bed, it would prove worth it, perhaps. But as I expand my raised bed gardens, I just can’t justify the cost of Mel’s Mix when the “perfect soil recipe” (with better topsoil) has the potential to perform just as well if not better.
  2. The Perfect Soil Recipe seems to have better longevity because of the amount of nutrients found in the soil, and it also had a more neutral Ph.
  3. No matter what blend I choose, it’s important to add diversity. I would include as many sources of compost and organic material as possible. The greater variety we can have with our organic material the better!

The Best Raised Bed Soil Blend

I loved doing this test in 2019 and since then I’ve continued to test in my garden. I took what I learned and adapted to what has been my go-to raised bed blend since.

What’s the formula?

  1. Tree limbs, logs, sticks, fallen leaves, and/or garden debris at the bottom of the bed
  2. Add roughly a 50/50 blend of compost (bulk and/or homemade) and topsoil (bulk and/or bagged).

The tree limbs and sticks not only help to lessen the amount of soil I need to obtain for a raised bed, but as they break down they create rich, nutritious organic matter.

Although this may be seen as a negative thing, as it breaks down, the soil level will drop. This “forces” me to have to add more compost each season, which continues to increase the longevity of the soil fertility.

The 50/50 blend of compost and topsoil form the basis of the raised bed soil. Sometimes I mix it; sometimes I layer topsoil and then compost on top. Both have worked equally well for me.

raised bed kitchen garden
When building this new raised bed kitchen garden, I chose a mix of native soil and Joe Lamp’l’s “perfect soil recipe” based on my experiment with raised bed soil the year before.

The key, I believe, is rich organic matter that is alive. You can learn more about that in What’s Wrong with my Raised Bed Soil?

How much soil you need for a raised bed?

One more thing you may be asking is how much soil will you need in your raised bed, regardless of which mix you choose? This handy online soil calculator will get you started.

For a specific calculator on how much peat moss, vermiculite, and compost to purchase if you go with Mel’s Mix, this soil mixture calculator will help you know how much of each to obtain.

What about you? What blends of raised bed soil mix have worked well (or not so well) for you?

43 Comments

  1. As a scientist I can attest to how awesome this test was! I thoroughly loved this post and will definitely be making use of the information. Many thanks.

  2. Thank you for sharing the results of your raised bed soil test. I too have had very poor results when using bagged garden soil and bagged compost. Last year I was short of my homemade compost and purchased some bagged compost, the results were very disappointing. The plants looked stunted and they did not produce any fruit.

    1. Same thing here, Clyde.

      I bought bagged mushroom compost and my tomato yield was pathetic. My cucumber died almost immediately, and the only thing that produced was basil. I gave the same tom seedlings to 4 friends and they all had incredible yields. So disappointing!

      Interestingly, I’ve always used bagged soil and compost because of where I live and this was the first time I got so burned.

      1. I also had the same experience as Clyde & Carrie. I did my first container garden last spring with a variety of bagged vegetable potting mixes and bagged compost & my results were pretty poor. Ended up with mold problems & my soil seemed to hold too much water, granted, I am in FL & it’s very humid here, but I never had these problems with my inground garden at my previous house (same area in FL). Seems to me like the bagged soils lack some important minerals & are full of too many course pieces of wood chips.
        I think I may try the perfect soil mix this fall.
        Thanks for sharing the results of your tests and the info about the soils, it’s been one of the most helpful things I have read on raised bed gardening soil so far!

  3. Jill, simply love your site so informative and leads an old 77 year old long time gardener to try different things and ideas. I used to have huge gardens but I have cut down to four 4×8 raised beds that I’ve had for about 15 years. I have came across 2 half size whiskey barrels and my question is what kind of soil or mixture would be best. Im thinking maybe planting bell or hot pepper or maybe a tomato. Keep your site going I love it!
    Jack

    1. Hi Jack, nice to meet you! If your whiskey barrels have a bottom, with just drainage holes, they will function more like a container than a raised bed. And as such, I’d recommend more of a potting soil mix to ensure good drainage. Add compost if possible, and be prepared to supplement with organic fertilizer throughout the growing season. I recommend fish emulsion when the plants are young, and a seaweed or kelp emulsion at flowering. Keep them consistently watered to prevent blossom-end rot, which is common in containers. Hope this helps!

  4. Thank you very much, Jill, for sharing the results of your soil tests. You have performed a wonderful, valuable and timely service for all of the gardeners who visit your site. Sharing your results with us will prove to be a tremendous time and money saver. Keep up the great work!

  5. Starting my first garden this year, so this is extremely helpful. Thanks for taking the time to do it and share the results!!

  6. Ugh. I just filled my two raised beds (first time ever using raised beds) with bagged “raised bed mix” and some peat moss. Sounds like I might need to amend it throughout the summer, huh?
    I did a soul rest myself and was pretty disappointed with the results—rather low nutrients.

    1. I do not believe all bagged soil will have the results that the bagged soil I bought did. I recommend as we all should do anyway, to keep a close eye on the early growth of your plants. If they don’t seem healthy, they grow slowly, or they have too light of a green color, it might be a good idea to add organic fertilizer like fish emulsion or kelp/seaweed emulsion. You might check to see if the raised bed mix had any fertilizer added. If not, I’d go ahead and add an all-purpose organic granular fertilizer to the top and let the rain water it in.

  7. Loved this information. We are putting in 6 raised beds with maybe 1 or 2 more. In 4 of the beds I put in cow manure, from bags, and bagged potting soil. I also put them in the 5th bed, but before putting them in I put a layer of plant debris from around the property, then a layer of my own compost, 4 bags of potting soil, then 4 bags of bagged cow manure, and another layer of 2 bags of potting soil. I may try the Perfect Soil for the 6th bed if I can find enough organic matter to add to it. Thanks again for the great information!!

  8. I am doing raised beds, the kind that are waist high. Last year was a disaster and I believe it was because I chose the wrong soil so this article is very helpful to me. My question is, do I replace the soil every year? Add fertilizer each year? Thank you for your help.

    1. Unless your soil was contaminated, there’s no need to replace the soil each year. But you should plan on adding about two inches of compost to the top. Don’t worry about mixing it in. I’ve never added fertilizer to my raised beds; instead, I focus on adding compost and then I may supplement my plants with organic fertilizer during the growing season if needed.

  9. Excellent post and thanks for that. I’ve also had this experience with bagged mix. I used one last year and had similar tomato results. I called the soil company to see what was in it and they said mainly lower level peat moss. I guess the peat moss on the top layer/level is of better quality. They said to amend it with perlite. I’m encouraged to hear that local soil is best. And you can’t beat free! Love your chicken moat, by the way. What’s not to love about chickens patrolling the perimeter for bugs. Just great.

    1. Interesting about the peat — I didn’t know there were differences. I’m a little confused about why they would suggest perlite. Perlite is mainly used for drainage, which generally peat is good at on its own (unless the lower level isn’t?). I’d suggest adding a good amount of organic matter (compost would be my first choice). And yes, we love our chicken tunnels! I always have company in the garden even when I can’t have them “in” the garden with me. 🙂

  10. This was such a helpful experiment! I also listened to the Podcast episode and found your explanations really helpful. It is nice to see the photos here. I’ve struggled to put together a good mix of soil for my raised beds. Last year, I used a bagged company from Maine that’s really respected in New England, but my veggies did terribly. (Tomatoes were ok, peppers and chard were completely stunted) I had it tested and there was no nitrogen and excessive amounts of phosphorus, potassium, and other nutrients. This year, I’m going to try for something kind of like Mel’s mix and the Perfect Soil Mix, with bagged topsoil, composted cow manure from a local company, vermiculite and perlite (not as much as Mel’s mix requires because so expensive), worm castings, and blood meal. We’ll see how it goes! Thanks again for doing this experiment!!!

  11. Hi Jill, thanks for the info! We have about 10 raised beds, most are filled with just bagged compost. We have ordered bulk topsoil and compost for some new beds this year. Every year we are refilling our beds, do you just add compost to the top? Or what are you adding to maintain ? We have just always added more compost to bring the height of the soil back up to the top of the beds, ?

    1. No, I did not use perlite in Mel’s Mix. It is vermiculite. I have used perlite in potting soil and soil block mix, but not in my raised bed soil, so I haven’t compared them side by side.

  12. We started a raised bed garden in April (prior to finding your site) using native soil, bagged topsoil, bagged mushroom compost and some homemade compost. Tomatoes and peppers were both stunted while squash, basil and marigolds seem fine. In-ground beds amended with this soil mixture produced stunted zinnias and four-o’clocks from seeds and turned a normal-looking sunflower transplant into something truly, hideously disfigured. After much research I think something I used was contaminated with an herbicide. Would it more likely have been the topsoil or the mushroom compost? I’m discouraged but determined to persevere and remove the tainted soil. Would this soil be safe to put on my lawn? How can I make sure my future bagged purchases aren’t contaminated? Thx for your help and for your informative site and podcast.

    1. I can’t say for sure, but you might look up non-organic mushroom compost. It seems I’ve heard that organic is really important for mushroom compost, but I can’t recall where I heard that. I have never heard of topsoil being contaminated. It’s possible your native soil could have been tainted by previous herbicide applications as well. As far as lawn, I’m not sure about that. You might contact your local cooperative extension agent and ask these questions to get a better idea what options you have.

    2. Thanks you so much. this article is beneficial for beginner gardeners.
      This is my first raise bed, and I was concern about the ratio of the components, but now I do have the FACT 🙂
      Sorry my English isn’t good enough.

      Mohammad
      Saudi Arabia.

  13. This is my first year with raised beds. I used Mel’s Mix. Plants are doing great. You are right, it was an investment!
    I enjoyed reading this so much!

  14. Love your info on raised beds. I see in the picture of the new bed (u shape) you have lined the sides. With what and why? Also filling the bottom with brush — Hugelkultur.
    My son is in the process of completing the form for me. Hoping to transplant my plants from containers. Is there any wood I should stay away from for the first layering?
    Thanks for the help.

    1. Thank you! The liner is landscape fabric stapled to the beds to prevent the soil from leaching out between the boards. (I don’t line the bottom of my raised beds with landscape fabric.) For your second question, the only wood I know of to possibly cause problems is black walnut (and, of course, any questionably-treated wood like railroad ties). Otherwise, I’ve had good success with pretty much everything I’ve used.

      1. Thank you for info. One other question – I have wood chucks in the yard every now and then . Would you use hardware cloth in the bottom of the raised bed? Any issues with the metal causing a problem?

        1. Yes, hardware cloth is a commonly recommended way to prevent ground-dwelling wildlife. I don’t personally have to use it but many gardeners do. I haven’t heard of any issues with the metal.

  15. I use a combo of alpaca manure, topsoil and mushroom compost
    My tomatoes grow to over 6ft. We get a ton tomatoes and cucumbers and jalapenos.

  16. Mel’s Mix: in lieu of the peat moss perhaps you could try COIR which is made from coconut husks. Coir seems to be more environmentally friendly than mining peat moss from Canadian boreal forests which are a great carbon sink.

  17. Thanks for sharing your results! I love a good garden experiment. I’m revamping my raised beds, and was really put off by the high cost and questionable ecological impacts of using Mel’s Mix. I’m going to give the Perfect Soil mix a try, hope it works as well as yours did.

  18. I like your report on soil types. I just put in my first raised bed for Dahlias, Zinnias, and, Marigolds. All are doing well. I hope to start another bed this Fall and let it winter over, ( there isn’t much winter in Georgia). I’m doing a Hugelkulture bednow.

  19. Never heard of Mel but looks like they’re using Coots soil recipe. Lookup Coots soil recipe for the rest of the amendments.

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