Topsoil is the uppermost layer of soil that contains organic matter and nutrients vital to plant growth. It provides the foundation for the establishment and development of plant roots.
Without sufficient amounts of quality topsoil, it’s nearly impossible to grow flowers, vegetables, trees, shrubs, and grass successfully.
As an avid gardener, I’ve learned proper soil preparation is one of the most important steps in starting any garden or landscaping project. Adding compost to enrich the soil is great, but you need adequate topsoil first to create an optimal growing environment.
Why Nutrient-Rich Topsoil Matters for Healthy Plants and Gardens
Topsoil is the uppermost layer of soil, usually the top 5-10 inches. It has the highest concentration of organic matter and microorganisms that are vital for plant growth and gardens. Here’s why quality topsoil is so important:
Nutrient-Rich Composition
Topsoil contains essential nutrients like nitrogen, phosphorus and potassium that plants need to thrive and grow well. These nutrients are absorbed easily via fertile topsoil.
Nutrient-Rich Composition
Topsoil contains essential nutrients like nitrogen, phosphorus and potassium that plants need to thrive and grow well. These nutrients are absorbed easily via fertile topsoil.
Good Drainage & Aeration
The loose texture of topsoil allows for adequate drainage and circulation of air and water to plant roots. This enables healthy root development.
Beneficial Organisms
The organic matter in topsoil feeds microbes, worms, and other beneficial lifeforms. These in turn enrich the soil further for optimal plant growth.
Anchoring Plant Roots
Plant roots grow and spread best in the relatively loose, nutrient-rich, and well-aerated environment of quality topsoil.
Avoiding Compaction
Topsoil prevents underground compaction, allowing roots to breathe and easily access moisture and nutrients.
Reduced Erosion
The organic content in topsoil makes it less prone to erosion damage caused by wind, rain or stormwater runoff. I have a Topsoil Erosion Calculator that can estimate how many inches of erosion can occur per year.
Shop Topsoil Options For Your Specific Project
While loam topsoil is great for general gardening needs, specialty soil options can also be beneficial for certain situations:
- Sandy loam topsoil promotes faster drainage in wet areas but requires more frequent irrigation.
- Silt loam topsoil retains more moisture for plants like azaleas and rhododendrons.
- Clay loam topsoil provides more structure for compaction-prone sites but requires added organic matter for porosity.
- Organic topsoil offers extra nutrients from compost, manure, etc. but is generally more expensive.
- Blended soil mixes can combine topsoil with compost, peat moss and fertilizers for custom mixes based on your plants’ needs.
The right topsoil choice depends on factors like existing soil conditions, the plants you’re growing and site considerations like drainage.
Shopping around and talking to knowledgeable soil suppliers can help narrow options. Ordering bulk topsoil also allows blending custom mixes by adding bagged organic amendments like compost.
Many homeowners end up with the native soils on their property, which may be clay, sandy or rocky based on local geography and geology.
While established plants can sometimes adapt to less-than-ideal soil conditions, adding specialty topsoil can really enhance growth.
For very sandy soils that drain quickly, topsoil with more clay content offers better water retention while still improving texture for plant roots versus 100% native clay.
For heavy clay soils, adding more sand and organic matter performs the opposite function by lightening the soil while increasing drainage and aeration.
Incorporating 4 to 6 inches of topsoil customized for your native soil makeup results in a blend that combines the best properties of each.
My heavy red clay soil is now much more balanced thanks to adding screened sandy loam topsoil – thanks to my Topsoil Amendments Calculator. The end result is healthier plants with more vigor from improved soil structure.
Now that we know how vital topsoil quality is for plant health in my garden and landscape, you should only purchase from suppliers you trust. Asking the following questions helps ensure the topsoil meets your needs:
- Where was the native soil harvested from? Mined topsoil retains more microorganisms than stripped topsoil.
- Has the soil been screened for debris and rocks? Screening improves consistency and usability.
- What are the percentages of sand, silt, and clay particles? Better topsoil blends balance all three.
- Does the topsoil contain any weed seeds, chemical residues, or contaminants? Request recent lab testing for purity.
- What organic matter percentage is in the topsoil? Higher is better for nutrient content.
- What types of compost, fertilizer, or other amendments were added? Get specifics on nutrient levels.
- Are there customer photos showing previous topsoil projects? Ask for visual quality evidence.
Doing research ahead of delivery helps avoid unpleasant surprises when the truck shows up.
Reputable topsoil sellers encourage questions and can explain their quality control procedures. Always inspect samples, get the soil tested, and ask for photos of the source piles before purchasing.
Many gardeners add raised beds to designate planting areas and improve drainage. Calculating topsoil is more straightforward when working with beds versus entire yards since it’s based on the bed’s square footage and depth (thickness).
A good rule of thumb for raised beds is to fill them half full with quality topsoil, leaving the remaining space for mulch and compost additions later.
This Topsoil Calculator site makes the math easy by having you input the length, width, and desired depth of your raised beds in inches. It quickly provides the cubic yards needed to fill your beds halfway, taking the guesswork and wheelbarrow counting out of the process!
For new in-ground planting beds, the Topsoil Calculator recommends a minimum of 8 to 12 inches of quality topsoil for robust growth. This provides adequate rooting depth for most vegetables, annuals, perennials, and mulching.
To figure cubic yards, input your bed’s length in feet down to the inch, times the width in feet down to the inch, then divide by 324. Finally, multiply the total by your desired depth in feet to get an accurate cubic yard estimate.
You can use the Topsoil Calculator to determine the total cubic yards of topsoil required.
Topsoil settles significantly from transport and spreading, reducing volume. Allowing for this compression is important when estimating needs.
I add an extra 20% to my yard coverage calculations for screened topsoil, and an extra 30% for fluffy unscreened soil. The Topsoil Calculator recommended padding those percentages, and I’ve found them to be very accurate.
I learned the hard way that skipping this step results in uneven settling and wasted material. Preparing the underlying soil upfront means the imported topsoil blends together better.
While 6 inches is recommended for general coverage, some plants need more or less topsoil depending on their rooting habits:
- Shallow rooted plants like ferns and ground covers need 4 inches minimum.
- Most annual and perennial flowers thrive at 6 inches.
- Vegetables and herbs prefer 8 to 12 inches of topsoil for robust growth.
- New sod needs a 4 to 6 inch topsoil base to establish successfully.
- Trees and shrubs require 12 to 18 inches of quality topsoil for strong roots.
Using the recommended topsoil depth/thickness guidelines from the Calculator ensures my plantings start off right. Trying to cut corners with thinner soil has never worked well in my garden. A little extra depth goes a long way!
For several small garden patches and beds in my yard, it made sense to use bagged topsoil for convenience. But for larger areas over 200 square feet, having bulk loads delivered is much more cost effective.
Bagged soil averages $3 to $5 per cubic foot. The Topsoil Cost Calculator estimates bulk loads between $15 and $50 per cubic yard is far more economical at those volumes. Even with delivery fees added, bulk soil offers major per-yard savings.
One bulk cubic yard bagged would take 27 bags! Just the labor of moving that many bags makes bulk delivery worth it for me. And bulk loads can be amended as needed with bagged organic matter like compost. For big projects, bulk is the definitely way to go.
Having topsoil delivered in bulk dump trucks is the most efficient option for most homeowners. But for small- to medium-sized projects, you can save on delivery fees by hauling loads yourself.
I recommend pickup trucks with trailers for hauling 0.5 to 1.5 cubic yards per load.
For my backyard project, I used an F-150 truck and a 6x10ft trailer to haul 0.7 cubic yards per trip. Knowing this yardage helped me budget loads and fees at the landscape supply yard. And not paying for delivery offset the cost of my time and fuel.
Owning heavy equipment like a skid loader or tractor is expensive and generally not realistic for most homeowners. But when doing major topsoil grading for new construction, renting this type of machinery can make the project more feasible.
As per my experience, I can say that tractor buckets commonly hold 1 to 2 cubic yards of soil per scoop. Skid loaders average between 0.5 and 1.5 cubic yards per bucket. This really speeds up moving bulk loads from delivery piles to spread locations.
Just be sure to get proper operating training for safety. Having an equipment rental company deliver and pick up the machinery on a job site basis helps make prepping and placing large volumes of topsoil much more manageable.
Adding topsoil isn’t just for outdoor landscaping – it’s also extremely useful for grading the soil floor in unfinished basements to prepare for flooring.
Six inches of loam topsoil creates a smooth, compacted subsurface for installing carpets, tiles and other flooring options.
The Topsoil Calculators make figuring those cubic yards easy. Just measure your total square footage and input the depth/thickness needed in inches. The calculator converts that to cubic yards so you know exactly how much soil to order.
This indoor use doesn’t require quite as much focus on nutrient content. But choosing quality screened topsoil ensures fewer rocks, roots, and debris that could damage flooring or create uneven spots. Prepping basement floors with topsoil has helped my installations go much smoother.
Major dirt moving projects like creating raised garden beds, grading slopes or leveling ground traditionally require hiring excavation machinery and operators.
But with the right topsoil volume calculations, site prep can easily be tackled as a DIY project.
I recommend planning the job in stages for manageability:
- Calculate needs and order delivery in phases
- Use tarps to stockpile extra soil as needed
- Start importing at the far end and work backward
- Shape and spread soil with rakes and shovels
With smaller volumes moved per stage, site grading by hand is very realistic. Just be sure to wear gloves, stretch well, and alternate tasks to avoid overexertion. Taking it slowly with the math planned out makes for a smooth, quality result.
My favorite pro gardening tip I’ve learned is to finish new topsoil areas with compost and mulch for a polished look. Spreading a few inches of compost enriches the soil, while mulch helps retain moisture and suppresses weeds.
Some landscapers recommend combining topsoil, compost, and mulch in layers for super fertile planting beds. Using calculators for each ensures you buy the right quantities of all materials for a flawless finished garden.