The dirt on the dirt(soil) in your raised bed garden

The soil that goes into your raised bed is just as important as the sunlight and water. With a good concoction your plants can be thriving in no time. The correct mix of nutrients, drainage, and density is especially important in a raised bed garden.

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Below you will find a wide variety of knowledge on the different ingredients that can go into a raised bed garden. I have listed a few cookie-cutter soil mixes, feel free to experiment with different proportions, it is intended to get you started in the right direction, at the end of the day only you can determine if the soil is the way you want it.

The “right” combination results in the end product being fluffy and well-draining.

Soil & Soil Additives

There are a great variety of things you can add to your soil. Each doing something a little different than the next. Being able to decide what to add to your soil will come to you much easier if you have a basic understanding of what is available to you.

Below you will find information on common soil ingredients. Using this information combined with the cookie-cutter mixes and your own intuition you should be able to determine how to build your soil concoction.


The top layer of soil that is high in organic matter and has naturally formed over 1000s of years. When purchasing topsoil there are two main types Blended Topsoil and “Organic” Topsoil.

Blended Topsoil

A mixture of mineral material, topsoil, and compost. This can be purchased in bulk from most garden supply centers. Soil quality is important prior to purchasing, be sure to ask for the most recent soil testing results. Most reputable suppliers will have this test done regularly.

Organic Topsoil

Contains shredded wood, moss, peat, animal manure, and whichever organic products the supplier decides. This is the most common topsoil to be found at hardware stores.

A word of caution against using this type, most of the ingredients will not be labeled. The “organic components” from supplier to supplier can vary greatly. This is fine as long as you don’t need or want to monitor your nutrient levels. However, for a gardener keeping a closer eye on everything it could be a spell for disaster. Just be aware of what you are purchasing and using and you will do just fine.

Garden Soil or Topsoil

Garden soil is topsoil enriched with compost and other organic materials. If you use garden soil extra compost and nutrient additives may not be necessary right away.

Peat Moss

A large absorbent moss that grows in dense masses on boggy ground. Peat moss is good for water and nutrient retention. While having a higher price than other soil additives, peat moss doesn’t break down as quickly (reuse) as coco coir would.

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Some of the drawbacks to peat moss can easily offset the pros. It is acidic and can increase the PH level of your soil. Also, the environmental impact that harvesting peat moss has is substantial, the disturbance of bog lands is responsible for a good portion of greenhouse gasses released every year.

Coco Coir

Coconuts! Here is a more sustainable and environmentally friendly substitute for Peat moss. Coco coir is a direct by-product of the coconut industry. While both brown and white coco coir is available, brown is used in horticulture. Brown fibers are harvested from ripe coconuts and are thicker and have better water retention.

Most coco coir is dehydrated prior to shipment and will need to be hydrated prior to mixing. My 5lb block took 20 minutes to fully soak up 8 gallons of water. THAT’S A LOT OF WATER!

Most coco coir is dehydrated prior to shipment and will need to be hydrated prior to mixing. My 5lb block took 20 minutes to fully soak up 8 gallons of water. THAT’S A LOT OF WATER!

Coco coir is inert, when using it you will need to add nutrients in the form of compost or other organic materials.


Compost is the result of the process called composting, which is when organic materials and inorganic are decomposed into a simpler organic form. Composting can be done in larger or small scales however, most hot composting requires a pretty good size pile.

Types of Composting

Aerobic Composting

This type of composting requires you to tumble or turn your pile to help break down materials more quickly.

Anaerobic Composting

Grab a nose plug for this pile, add your scraps to the top and forget about it. The stinkier and slower of the three types here.


Worms! Worms! Worms! Utilizing you guessed it worms, oxygen and moisture this compost is a great additive to your garden soil. Worms can easily be maintained, emit very minimal odor, mostly regulate their own population, and can give you free bait for fishing. Keeping worms is very simple and can be done indoors or outdoors.

There are many more types of composting available to you, these are the main 3 that are discussed throughout. Keep on the lookout for a follow up article entirely about different types of composting.


Applying too much fertilizer can cause root burn on younger plants!

Applying too much fertilizer can cause root burn on younger plants! Fertilize with caution! Give your plants around 2 weeks to adjust to their new home. After this period begin to apply fertilizer once a week. Try not to over fertilize, usually 4 application over the course of 8 weeks is enough to get you through the growing season.

Your plants will love the added nutrients and you’ll love the added produce, flowers, or weeds (whatever your fancy). Sticking with an easy to use liquid fertilizer will help remove some of the struggles of measurements as your starting out. If you decide to buy your fertilizer from a store be sure to read the label and know what your are taking home and putting on your dinner table later in the fall.

Photo by Lisa Fotios on

Another at-home method for a liquid fertilizer is Compost Tea, you create compost tea by steeping worm castings in water for 3 days, the resulting liquid will be full of nutrients from the castings.

Soil Amendments

The following substances can help with a variety of issues that you may encounter with your raised bed garden or any garden for that matter. From nutrient retention to supporting a sturdy root structure the following are must haves in any soil mix.


For any water loving plants you have to have vermiculite. In regards to water retention it is 2nd to none and will help keep your garden hydrated and deliver the moisture when needed.

Horticulture Vermiculite is formed by rapid heating of hydrated laminar minerals which results in the accordion like shape with multiple layers.

Vermiculite is a great tool to use in the garden, adding it to any seed starting mix or even growing plant cuttings in pure vermiculite will allow the roots to grow and support the plant.


Aeration and drainage are the largest benefits of perlite. Use perlite when a faster draining soil is required. It also helps prevent compaction by creating little pockets under the surface.

Be aware that adding too much perlite to your potting mix can result in fluoride burn (brown tips of leaves is a notable symptom).


Limestone is a lifesaver in terms of your gardens Ph levels. Sprinkling a little limestone in your garden can help balance the soil to a more suitable and sustainable level for the plants to thrive.

Adding limestone into your fertilizer is a great way to apply it. By preventing the build up of harmful nutrients in the soil and safely increasing the calcium levels limestone is a great ally to have.

Limestone raises the pH level to a neutral variety beneficial to flowers, usually between 5.5 and 6.5.

By being overly eager in this situation with sand you may end up with cement. If you decide to mix sand and clay together the results will make a great sidewalk or pathway.

Sand when added in the correct amounts greatly improves water drainage. There are only a few plants that will enjoy having this mixed in by their roots. These plants enjoy a dry soil.

  • Artemisia
  • Borage
  • Fennel
  • Germander 
  • Lavender
  • Mullein
  • Oregan
  • Rosemary 
  • Sage 
  • Santolina
  • Soapwort
  • Southernwood
  • Thyme
  • Yarrow

Plant list source

DIY Mixes

I am an affiliate and links located throughout the article will provide me with a commission on any purchases made.

If you are looking to purchase any soil amendments or additives be sure to shop around. True Leaf Market has a limited selection as of right now however, it is a good place to start.

More from the blog

Myers Greens LLC

Myers Greens is a nursery located in southwest Iowa. With the main goal of providing top quality microgreens and fresh herbs. Follow the blog to keep up to date on what we are growing.

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Published by Myers Greens LLC

Nursery / Growing Operation located in Southwest Iowa.

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