The raised bed gardening is an easy option for gardeners especially when you are a beginner in gardening. But a question always bothered the gardeners that what growing medium will be the best one for a raised bed?

Should you choose topsoil or compost for your raised bed?

Both topsoil and compost are good for raised beds depending on your soil condition and usage of the products. Compost is richer in nutrients on the contrary topsoil can contain the nutrients of it much longer. Thus, the soil condition can make a difference in the case of receiving benefits. 

Native soil or your usual garden soil isn’t an ideal option for your garden beds. For this, you need to use the proper medium to make it more convenient, right?

There are more things to add about using compost and topsoil that you need to know to make the right choice, so, let’s dig in deeper!

Topsoil vs Compost
Table of Contents

Let’s know about topsoil

Why you will choose topsoil for your raised beds? I mean you can choose compost too, right? Well, before you decide about what to use, let’s know some more about topsoil.

What is topsoil?

Topsoil is basically filler soil and makes up the bulk of most soil mixes. It is the upper layer of the soil that is high in organic materials and nutrients.

It is formed by the slow weathering of rocks and decaying organic matter over thousands of years. Usually, the top 5 to 10 inches (13-25 cm) is considered as topsoil.

Usage of topsoil

Topsoil is basically used for planting on the ground or raised beds. It has a heavy texture that can hold moisture and water for a long period. Topsoil is regarded as a speck of dirt.

One of the popular uses of topsoil is to make a new plant bed or refurbish your garden. If you want to replenish the nutrients lacking in the plants, topsoil is a good choice. You can also get the desired depth of soil for your garden bed by using a topsoil layer on the top of the garden soil.

Besides, plants and flowers draw their nutrients from the dirt they live in and that’s why topsoil beds are best for it. Using topsoil for bed vegetable garden is also a good choice, no doubt. The organic nutrients of topsoil will encourage your plant bed to grow and flourish thus provide a healthy medium for your plant,

Moreover, you can add sandy topsoil to the garden beds if there are water delivery issues. Sandy topsoil will help to improve the packed soil that is blocking the water to soak in. You can also add some topsoil to the grassy lawn to make garden beds and start a garden from scratch.

Let's know about compost

Okay, it’s time to know our other option compost. Compost is also beneficial for your soil. But, is it good to use in your garden beds? 

Before reaching that point let’s know some basic things about compost.

What is compost?

Compost is made by decomposing organic materials into simpler organic and inorganic compounds in a process known as composting. Good compost contains beneficial nutrients and organisms. It is basically a short-term processed product and mostly used as a fertilizer in the soil.

Usage of compost

Compost is mainly considered as a fertilizer. It is used for conditioning the soil and increasing the fertility as well as nutrients of the soil. It is also used for retaining the moisture of the soil. 

Besides, it is good for suppressing plant diseases and pests. It encourages the production of beneficial bacteria and fungi that help in breaking down the organic matter to create humus.

Compost helps the sandy soil to retain water to hold the soil moisture as well as helps the tightly bound particles of clay or silt soil to break. Using good quality compost can ensure the spread of roots, proper water drainage, and aeration.

It also prevents soil erosion and holds the soil nutrients for a long time.

Which will be better for your garden beds

After knowing about the topsoil and compost now it is time to know whether you should apply topsoil or compost for your garden bed.

When you should apply topsoil?

Basically, bulk topsoil is collected from fields or building sites or you can simply buy them from any local garden center. It’s sometimes combined with organic materials for making it more nutrient-rich. Whether full of clay or sand, this soil is used for building up soil height to the desired level.

The organic matter of the topsoil stays in the soil for a long time. But when the organic matter started to decompose, the sand and clay still remained. That’s why when you start a vegetable or flower garden from scratch, it is good to choose topsoil for making deeper beds.

Besides, you can put topsoil layers on the surface as much as the layer of soil you need. You can use it too for leveling the spot where you just removed a large tree. 

However, topsoil may contain weed seeds and that can damage the growth of your planted crop. So, take care of this fact. 

When should you use compost?

When you want to improve the quality of your soil, it is good to choose compost.  Compost is enriched with more nutrients than topsoil. Though the organic matter decomposed very soon, the nutrients are slow-released. 

It has a neutral pH level and due to its microbial activity, it can prevent disease. Besides, it has no weed seeds, so, there is no risk of weeds. Whenever you are installing sod or sowing seed, you should add compost by trilling.

However, compost is not a good option to use as a whole for planting the crop. You need to mix compost with ground soil.

Can you use both for the garden beds?

Yes, you can use both for your garden beds. Deep inside the soil, you can put the compost and on top of that, you can make the layer of topsoil. Or else, you can mix the compost with the topsoil and then make the layer of soil. 

This will help to amend the soil of your garden beds, provide essential elements, and also you will have the garden beds with the desired depth.

Extra materials to add to your topsoil and compost for raised beds

Extra materials to add to your topsoil and compost for raised beds

The soil matters a lot for the growth of your plant in a healthy way. To ensure rich soil beds topsoil or compost is not enough. You can put some additional materials with your topsoil and compost mix or to your individual topsoil or compost layer. 

Let’s talk about them.

  • Leaves:  Well-aged, shredded leaves are one the best additions. They add great bulk. For using them in your garden, you need to shred the leaves, wet them down for about six months to one year. After that, they will rot and you will be able to mix them in the soil.
  • Mineralized Soil Blend:  Minerals are one of the most important ingredients for plants. Mineralized soil blend is widely available and, typically, locally sourced. You can choose to use a Granite or Azomite blend of soil.
  • Worm Castings: Worm castings aka worm manure are significantly higher in all the primary nutrients your plants need to thrive. In fact, they add five times the nitrogen, seven times the phosphorus, and ten times the potassium than ordinary topsoil.
  • Castings add one more layer of complexity to overall soil makeup. It is great for making high-quality garden soil.
  • Mushroom Compost:  This dark brown, pliable organic material is a byproduct of ingredients in which mushrooms grow. Mushrooms are grown in mixtures of natural materials and by the time that materials get composted, bagged, and sold as mushroom compost; it’s light and crumbly.
  • It contains about 3% nitrogen and potassium, a bit of phosphorus, and other bonus elements, like magnesium and calcium. Since it’s a neutral pH (6.5-7.0), it won’t have an impact on your soil pH.
  • Ground Bark:  Ground bark is a good carbon source. It will break down over time, and its coarse texture provides space for the movement of water and oxygen through your garden beds. Ground bark brings a diversity of particle sizes that can really amp up your plant health. Use shredded bark instead of fresh wood chips.
  • Composted Cow or Poultry Manure:  Composted manures added to today’s garden soil can contain synthetic herbicides that are still active, even in well-composted manure. For that reason, use cow or poultry manure but not horse manure. Horse manure can be a killer compost in your compost pile.
  • Peat Moss:   Peat moss is not a sustainable material. It takes hundreds of years for peat to develop in peat bogs. However, it can aid water retention, but once peat moss dries out, it is difficult to re-hydrate.
  • Some additional materials worth consideration as additives:
  • Biochar: Biochar does have some nutrient value. It’s a pure carbon source that doesn’t break down, but it does help make existing soil nutrients available to plants.
  • Fire Ash: If your fire ash is all wood-based, it can be a good addition to your compost pile. Don’t use charcoal fire ash, as that may not be good for your organic garden soil.

So, you can add the above-mentioned additional to your raised beds

Final words for you

As you can see that both topsoil and compost can work for making your flower or vegetable garden beds, you can choose them based on your soil texture and condition.

If you want to increase the soil level and you have higher soil quality, you can choose bulk topsoil. If you have clay soils, then you can use sandy topsoil and in the case of sandy soils, it is vice versa. 

If your soil surface lack nutrients then you can mix bulk compost with your native soil or topsoil. There are many sources of compost like you can use, cow manure, kitchen scraps, grass clippings, and so on.  

Or you can use a bed soil mix that contains both topsoil and bulk of compost. The choice is yours.

But make sure your plants and plant roots get enough plant food. Happy gardening!