The Best Soil for Raised Beds

The right soil is the key to making your raised bed garden flourish.

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The Best Soil for Raised Beds Option

Photo: amazon.com

You already know that sunlight and water are essential building blocks of life. For plants, soil is another piece of the puzzle. Soil doesn’t just deliver nutrients to hungry plants. Good soil also improves airflow around plant roots to avoid compaction, retains moisture while improving drainage, and supports a vast ecosystem of microorganisms that boost plant health.

Gardening with raised beds means you have control over the soil. You aren’t stuck growing in and amending subpar soil on your property. The best soil for raised beds depends somewhat on what you’re growing, but most options are suitable for a variety of uses.

  1. BEST OVERALL: Nature’s Care Organic & Natural Raised Bed Food 
  2. BEST BANG FOR THE BUCK: Organic Plant Magic Compressed Organic Potting Soil
  3. BEST ORGANIC: Miracle-Gro Raised Bed Soil
  4. BEST TOPSOIL: Michigan Peat 5540 Garden Magic Top Soil
  5. BEST FOR VEGETABLES: New Coast of Maine Organic Raised Bed Mix
The Best Soil for Raised Beds Option

Photo: amazon.com

What to Consider When Choosing the Best Soil for Raised Beds

Growing flowers and food in raised beds differs from growing directly in the ground. Consider these key points before you dump a load of dirt into your raised beds.

Raised Bed Height

Knowing the size of your raised bed will help you determine how much soil you need to fill it. Thankfully, there are plenty of handy calculators that can help you out with this task. The taller your raised bed, the more soil you’ll need. If you prefer a taller raised bed, perhaps to eliminate back-breaking bending, you can build a raised bed or buy a tabletop model, which will require less dirt. Alternately, you can fill the bottom of a tall ground-level bed with filler like dead leaves or cardboard to minimize the amount of soil mix you’ll need to purchase.

Plant Type & Root Depth 

Some plants have deeper roots than others. Generally, a good rule of thumb is to build a raised bed that’s at least 6 inches deep. This depth will accommodate many crops. However, if you plan to grow root vegetables like carrots, a depth of 12 inches is preferable.

Raised beds are great for any kind of plant but work particularly well for growing vegetables. Elevating your growing space keeps weeds at bay, warms the soil up faster in the spring, and prevents compaction. You also start with pristine soil with a neutral pH, which makes it easy to grow pretty much anything.

Soil Components

Different gardeners have tried-and-true soil mix recipes, but it’s agreed that you should avoid settling for uber-cheap bags of soil when filling beds. The cheapest bags are usually low quality and full of weed seed, debris, and other nasty contaminants. They’re also unlikely to contain many valuable nutrients. A good soil mix contains topsoil, a small amount of substrate, and a significant amount of compost, which is filled with nutrients to help improve the soil condition.

Compost from multiple sources is best—it can even come from your backyard pile. Topsoil is basically filler soil and makes up the bulk of most soil mixes. It’s not very rich in nutrients but is a necessary component that contains organic matter. Finally, the substrate makes up a small bit of a soil mix but is extremely important. It helps control moisture content in the soil, which is exceptionally important in a raised bed. Some substrates that might appear in soil mixes include peat moss, rock phosphate, vermiculite, perlite, and coco coir. Be careful to avoid adding too much peat moss, which can increase the acidity of your soil and throw off the pH balance.

Some gardeners prefer to fill raised garden beds with a topsoil-free mix, using equal parts compost, perlite, and coco coir. It makes for an excellent, fluffy, moisture-retaining growing medium.

In the world of soil, organic refers to organic materials such as compost and mulch. Nonorganic materials aren’t necessarily harmful, they’re just inert and include things like pebbles, rock phosphate, and perlite. Nonorganic soil that contains no organic matter lacks nutrients and is also free of contaminants. These terms help describe the soil’s content.

The USDA’s National Organic Program (NOP) covers farm practices regarding soils and other substances applied to crops. In addition, the Organic Materials Review Institute (OMRI), a volunteer organization, lists products that organic farmers can use to produce food. Many soils available to consumers have the OMRI listing.

Topsoil

Topsoil isn’t the same as garden soil. As the name suggests, it’s the top layer of soil. It’s a general-purpose soil that’s ideal for filling in garden beds in the landscape or preparing a bare lawn for growth. It’s not very nutrient-rich, but it contains an important organic matter, so it’s not entirely useless. If you buy topsoil bags and plan to use them to fill your raised beds, pour them in first, since topsoil makes a great base layer and filler.

Fertilizer

The best raised bed soils contain nutrients. Organic, natural fertilizers include compost, sea kelp, and worm castings. These types of fertilizers help improve the quality and condition of soil without you having to worry about contamination. After all, too much fertilizer is not a good thing. The slow-release properties of organic fertilizers prevent potentially harmful buildup and ensure that your plants aren’t flooded with nutrients all at once, which can cause them harm.

Some soil mixes may contain synthetic fertilizers. They provide a quick nutrient boost but don’t improve soil condition and texture like organic options. This is why it is best to choose or make a soil mix with organic nutrient sources like compost.

Our Top Picks

Here are some soil recommendations to help fill your garden beds. All you’ll need to do is slip on your gardening gloves, open up the bags, fill up your beds, and get growing.

Best Overall

The Best Soil for Raised Beds Option: Nature’s Care Organic & Natural Raised Bed Food
Photo: amazon.com

Nature’s Care Organic & Natural Raised Bed Plant Food will feed your newly transplanted edibles for up to two months. The OMRI-listed organic soil can be used on its own or added to beds as an amendment. A single 3-pound bag can amend a standard 4-foot by 4-foot raised bed. For larger beds, add ½ cup of Nature’s Care for each square foot of the bed to enrich soil or work into the top 6 inches of soil when planting your vegetables.

Best Bang for the Buck

The Best Soil for Raised Beds Option: Organic Plant Magic Compressed Organic Potting Soil
Photo: amazon.com

Don’t be fooled by the small bag size of Organic Plant Magic Compressed Organic Potting Soil. This stuff expands when you water it—up to seven times its size. The mix contains worm castings and coco coir, which provide necessary plant nutrients and help retain moisture. It’s a great choice for drought-prone areas. The expanding mix comes in a 2-pound bag.

Best Organic

The Best Soil for Raised Beds Option: Miracle-Gro Raised Bed Soil
Photo: amazon.com

The OMRI-certified Miracle-Gro Raised Bed Soil provides organic matter needed for good drainage. The raised bed soil requires no mixing. Designed specifically for raised beds, the premixed blend comes in 1.5 cubic foot bags. It takes about three bags to fill a 2-foot by 2-foot bed that is 1 foot high.

Best Topsoil

The Best Soil for Raised Beds Option: Michigan Peat 5540 Garden Magic Top Soil
Photo: amazon.com

Use a large (40-pound)  bag of Michigan Peat 5540 Garden Magic Top Soil to fill in holes on your property or add bulk to your raised garden beds. Adding the peat-based and sand topsoil can help improve the texture of heavy, compacted soils and increase moisture retention in sandy ones.

Best for Vegetables

The Best Soil for Raised Beds Option: New Coast of Maine Organic Raised Bed Mix
Photo: amazon.com

New Coast of Maine Organic Raised Bed Mix is an OMRI-listed organic soil made specifically for raised vegetable gardens. It contains kelp meal, manure, worm castings, mycorrhizae, greensand, and biochar to provide nutrients to plants and prevent leaching after heavy rains. The bag holds 1 cubic foot of the organic soil mix.7

FAQs About Your New Soil for Raised Beds

If you still have concerns, here are some answers to a few common questions about soil for raised beds.

Q. How many soil bags do I need for a raised bed? 

It depends entirely on the size of your raised bed. If you know your garden bed’s dimensions, you can plug them into a soil calculator to find out how much you need.

Q. How do you prepare the soil for a raised bed? 

If you’re buying soil in bags, it’s typically premixed, so there’s not much to do other than water it before planting. Watering it prior to planting, using either a watering can or garden hose, ensures your plants have enough moisture to get started growing.

Q. Is topsoil good for a raised bed? 

A topsoil product is a great filler, but it shouldn’t be the main soil mix you use for a raised bed. Your plants need nutrients, and topsoil is not rich in organic matter like compost.

Q. Can I use only compost for a raised bed? 

Yes. In fact, the Square Foot Gardening Foundation recommends a compost-only option for gardeners on a budget or those who don’t have access to other mix-ins. However, while this can be cheaper (if you have access to free compost), the soil in a compost-only bed can become compacted.