From Compost to Amendments: Soil Solutions for Raised Garden Beds

The Cottage Peach is reader-supported. When you purchase through links on our site, we may earn an affiliate commission at no additional cost to you. All opinions are our own.

I’ve been gardening for most of my life in one form or another, but around ten years ago I was diagnosed with psoriatic arthritis, and since then I’ve had a whole decade to come up with the best gardening hacks to and gardening tools for gardening with chronic pain and low energy.

Psoriatic arthritis often confuses people who don’t have it - its cousins rheumatoid and osteoarthritis are far more common, so there’s a misconception that psoriatic arthritis isn’t as serious or doesn’t have as much of an impact on quality of life as these more well known forms of arthritis. The fact is that psoriatic arthritis is more than a skin condition. I experience severe joint pain and fatigue, just like someone with rheumatoid arthritis or osteoarthritis. I just get the added “bonus” of sensitive dry skin too. While exercise can help with my symptoms, it can also make them worse if I push myself too hard. I’ve had to learn my physical limitations by testing them, and they are a lot lower than someone living without an autoimmune disease. The idea that arthritis is an “old person's” condition is so pervasive that people often think it can’t really be that bad, especially since I don’t look sick and I’m not old. But invisible illnesses like arthritis and other autoimmune conditions can dramatically change your life, no matter your age or outward appearance.

In order to continue with my love of gardening even with arthritis, I invested in gardening tools that would make it possible for me to continue doing what I love. The biggest change I made in the garden to support my body came in the form of 6 new elevated garden beds from Gardener’s Supply Company.

Self-Watering Elevated Planter Box, 2' x 8'

These no-bend garden boxes keep plants hydrated via a series of innovative, connected reservoirs that deliver water to roots on demand. Four generous 5-gallon reservoirs extend the time between waterings and create more even moisture throughout the bed. And, since water is drawn primarily from the bottom instead of applied from the top, less water is lost to evaporation too! 10" planting depth accommodates a wide variety of crops, from tomatoes to root-crops like carrots.

The height of the planter box has other advantages too: fewer weeds, reduced maintenance, and fewer critters nibbling at your prize plants. The sturdy aluminum legs won't buckle or sag, and the wood is naturally rot-resistant and safe for your organic crops. Best of all, it allows me to garden at table-height, eliminating the bending and kneeling that makes gardening difficult on my joints. They are made of durable cedar wood with metal legs, and I like that the natural materials blend in seamlessly with the environment.

After building and placing my raised garden beds, it was time to fill them. But understanding what soil is best for raised beds isn’t always as straightforward as it seems. Filling raised garden beds will either set your garden up for success, or failure. The good news is once you’ve finished reading this post you’ll know exactly how to fill a raised bed cheaper, what to fill your raised beds with, what is the difference between garden soil and topsoil and more.

What should I fill my raised garden bed with?

The goal is to fill your raised garden beds with a mix of components that will deliver nutrients to your growing plants and encourage the right amount of water retention and drainage. You can accomplish this by putting organic matter such as old logs, sticks, grass clippings and leaf mold at the base, followed by a layer of topsoil and then finally a layer of compost.

The ratio that you use is going to depend on a lot of factors specific to your local climate. For example, in especially damp climates you’ll want to incorporate significantly more drainage. And, if you’re growing vegetables or other produce, you’re going to need a higher ratio of nutrient dense compost or fertilizer.

You can get bagged soil and compost from local nurseries, but it’s a lot more economical to have your soil delivered in bulk. For my six beds, I needed 3 yards of soil. I wanted to buy the soil in bulk because the cost would be less than half and I wouldn’t need to worry about recycling all those bags, but since my beds are raised off of the ground there’s no way they could support the weight of true garden soil - I needed a lightweight potting mix blend that would drain well but hold some moisture. I went with Coast of Maine potting mix because it’s some of the best soil you can buy, and the bags were recyclable at the same drop off points you can recycle your plastic shopping bags at in grocery stores.

If you do decide to get bagged soil, keep in mind that soil that is sold at big box stores like Lowes and Home Depot is questionable quality at best - in fact, last year there was a huge scandal because large amounts of this bagged soil were found to be contaminated with herbicides. It’s much safer to get your bagged soil or bulk soil from a local garden nursery that specializes in products meant for growing food and flowers. The last thing you want is to have all your hard work planning and planting your garden go to waste because your plants aren’t able to thrive in the soil that you used.

It’s very important not to underfill your beds. It will settle and sink down a lot more than you think. In addition, if you use too much organic matter like leaves this will cause your soil level to sink even more dramatically as the material decomposes throughout the season. This can happen pretty quickly. You’ll also need to top off your raised beds with a compost blend at the beginning of each new gardening season to accommodate for soil nutrients lost to plants using it up and general settling. A fresh layer of compost on top of your raised beds will revitalize the soil and make sure it is ready to continue helping your plants thrive for many years to come. You can also plant a cover crop in the fall to add additional nutrients to your soil, or use a mulch like wood chips that will slowly release nutrients as it breaks down.

How do you fill a raised bed cheaply?

If you’re on a tight budget for filling raised garden beds, I’d recommend the hugelkultur method. Hugelkultur is a centuries-old, traditional way of building a garden bed from rotten logs and plant debris. Buried in a hugelkultur bed, decomposing wood releases water and nutrients into the soil to conserve precious resources. This method is popular in permaculture and allows you to use less soil and more found organic matter that is free. Hugelkultur beds hold moisture extremely well and are great for dry climates. Don’t let a small budget keep you from gardening. There are many ways to improve the quality of your soil over time even if it isn’t that great in your first year.

Where can you find garden soil for raised beds?

The best place to find high quality garden soil for your raised beds is at your local garden nursery. Look for a topsoil/compost blend or raised bed mix. Sometimes you can even find local companies that offer residential composting services and then resell the compost as its own product. This is more common in rural areas.

What should you not put in a raised bed?

Avoid putting any painted or pressure treated woods in the base of your raised beds, as toxic chemicals can leach from the wood into your soil and plants.

What is the difference between garden soil and topsoil?

Garden soil is topsoil that has been enriched to make it better suited for plant growth. Amendments may include compost or other organic matter, and some soils – like perennial potting mixes – have added ingredients to encourage growth of specific types of plants.

Is topsoil OK for raised beds?

You should never use only topsoil for raised garden bed soil, or only compost. Your plants need a healthy balance of both in order to grow properly. This will depend on your climate and if any of your plants are heavy feeders that require lots of fertilizer. A general rule of thumb is to use a ratio of one to one - fifty percent topsoil and fifty percent compost.

Do you need special soil for raised beds?

There are many specialized garden soil for raised beds mixes available both commercially as a pre-bagged product and in bulk from local nurseries. I always recommend getting the best soil for raised beds you can afford, since it is the building block that will nourish your growing plants and give it what it needs in order to produce well. These blends are most likely to give you the best results. But plants are resilient creatures, so if your budget is limited or you don’t have access to the highest quality soil for raised beds, don’t let that stop you from trying to grow! You can plant cover crops and add liquid fertilizer to improve the quality of your soil over time.

Are you filling raised garden beds this year?
let me know how you grow in the comments!