Quick Answer
Garden soil can be used on lawns in some cases but it’s generally not recommended. The main reasons are that garden soil and lawn soil have different properties. Garden soil is often heavier, retains more moisture, and has a different pH than ideal lawn soil. It’s better to use a soil blend formulated specifically for lawns or to amend existing lawn soil with compost.
What is Garden Soil?
Garden soil is soil that is meant for use in vegetable gardens, flower beds, and planting areas. It has certain properties that make it well-suited for growing plants:
- It has a high organic matter content from compost, manure, peat moss, and other amendments.
- It has good drainage and aeration from perlite or vermiculite.
- It retains moisture well due to the organic matter.
- It has nutrients for plant growth like nitrogen, phosphorus, and potassium.
- The pH is between 6.0-7.0, ideal for most plants.
These traits allow garden soil to support the growth of vegetables, flowers, shrubs, and other garden plants. The soil stays moist but also drains well and provides nutrients and space for roots to grow.
The high level of organic matter is especially important. This comes from materials like compost, manure, leaf mold, grass clippings, and peat moss. The organic content performs several vital functions:
- It improves the soil structure, creating spaces for air and water.
- It releases nutrients as it decomposes.
- It retains moisture and nutrients for plant uptake.
- It supports beneficial microbial life in the soil.
Gardeners often enhance their soil further by adding fertilizer, compost, manure, and other amendments each year. This ensures the soil stays nutrient-rich to support the demands of growing plants.
What is Lawn Soil?
Lawn soil is the existing soil underneath your grass. It has different needs than garden soil because its purpose is to support grass growth instead of vegetables or ornamental plants. Ideal lawn soil should have these properties:
- It is moderately fertile but not overly enriched.
- It drains well to avoid puddling or waterlogging.
- It has a near-neutral pH between 6.0-7.0.
- It has moderate organic matter but not too much.
- It has good aeration and oxygen circulation.
Lawns need soil that is somewhat nutrient-poor so the grass grows slowly. Fast-growing grass requires frequent mowing and risks disease and thinning. Moderately fertile soil produces consistent, slow growth instead of surges of growth followed by deficits.
The soil should not be too dense or heavy. Lawn grasses need good drainage so excess moisture doesn’t saturate the roots. Light, loamy soil is ideal for lawns since it holds some moisture but drains well. Clay soils often need amendments to reduce compaction.
A proper pH near 7.0 allows nutrients to be available to the grass. Acidic or alkaline soils can tie up nutrients. Organic matter improves moisture retention and structure but too much can make the soil stay wet. Aeration is needed periodically to circulate air to the roots.
Key Differences Between Garden and Lawn Soil
There are several key differences that make garden soil unsuitable to simply spread over an existing lawn:
1. Organic Matter Content
Garden soil has a high level of organic matter, usually over 5%. This is beneficial for growing plants since it retains moisture, improves drainage, and adds nutrients.
Lawn soil only needs 2-4% organic matter. Too much can lead to compaction and waterlogging. Grass prefers soil that drains readily.
2. Fertility Level
Garden soil is formulated to be nutrient-rich to support growing vegetables, flowers, and other plants. The nutrients come from organic matter, fertilizers, manure, and compost. Plants need a constant feeding of nutrients.
Lawn soil should have moderate fertility. Grass that grows too fast due to high fertility requires frequent mowing and risks disease. Slower growth allows it to stay healthier.
3. Soil Structure
Garden soil is often loamy with a blend of particle sizes. This creates spaces for moisture retention, drainage, and root growth. Amendments like perlite improve aeration.
Lawns grow best in loamy soil with a balance of sand, silt, and clay. Extremely dense soils can become compacted under foot traffic and prevent air circulation to the roots.
4. pH Level
Garden soil is normally neutral with a pH of 6.5-7.0. Different plants need slightly different pH levels, but this range works for most vegetables, flowers and ornamentals.
Lawns grow best around 6.5-7.0 as well, though they can tolerate more variance. Soil that is too acidic or alkaline creates nutrient deficiencies.
5. Drainage
Garden soil often has amendments to improve moisture retention while still draining adequately. The goal is to keep plant roots moist but not waterlogged.
Lawn soil must drain readily to avoid saturation of the grass roots. Puddling and soggy soil causes lawn diseases and thinning. Lighter, loamier soil provides the best drainage for lawns.
Can Garden Soil Be Used on Lawns?
Garden soil can sometimes be used to topdress lawns but there are downsides to avoid:
- It may compress and reduce aeration due to the higher organic content.
- It can stay excessively moist and lead to fungal diseases in the lawn.
- Nutrient levels may be higher than grass needs, causing rampant growth.
- Drainage could be impaired compared to proper lawn soil.
With that said, here are some instances where using garden soil makes sense:
- The existing lawn soil is extremely poor quality. Garden soil used sparingly can enrich it.
- The garden soil closely matches healthy loam in structure and drainage capacity.
- The soil is thoroughly mixed into the top few inches rather than layered deeply.
- The lawn is overseeded so grass fills in completely.
In these cases, garden soil can potentially supplement and improve the lawn. But it shouldn’t be used excessively, as it does not perfectly match what grass needs. It’s best to test the drainage and amend garden soil before applying it.
A better solution is to purchase a good quality soil blend specifically meant for lawns. Look for topsoil, loam, or lawn soil without excessive organic matter. Or amend the existing lawn soil with a measured amount of compost or fertilizer tailored to grass.
How to Add Garden Soil to Lawns
If you do decide to incorporate some garden soil into your lawn, follow these tips:
Test the Soil First
Before amending with any new soil, send samples of your existing lawn soil for laboratory testing. This will tell you the soil texture, organic matter content, pH, and nutrient levels. Compare these to the garden soil’s properties. Make sure they are reasonably compatible.
Aerate the Lawn
Use an aerator to punch holes in the lawn before topdressing with new soil. This allows the soil to filter down into the lawn rather than compressing on top. It also improves drainage and oxygen flow.
Incorporate Evenly and Lightly
Spread a thin layer of garden soil across the lawn using a rake. Only use up to 1/4 inch at a time. Work it down into the holes made by aerating so it mixes into the top few inches.
Water Thoroughly
Water well after topdressing to wash the new soil down into the lawn. This helps settle it into the root zone. Wait until it dries between watering to avoid oversaturation.
Overseed with Grass
Apply grass seed over the lawn after topdressing. Select the same grass variety already growing. This ensures the lawn fills back in completely.
Fertilize Lightly
Apply a balanced, slow-release fertilizer at half the normal rate after several weeks. This feeds the grass without pushing excessive growth. Avoid high-nitrogen formulas.
Monitor Drainage
Check how well the amended lawn drains after heavy rain or watering. If it puddles or stays soggy, aeration and soil amendments are needed.
Alternatives to Garden Soil for Lawns
In most cases, it is better to improve lawn soil using these methods instead of garden soil:
Loam or Lawn Soil Mixes
Purchased loam, topsoil, or lawn soil blends contain balanced organic matter and nutrients tailored for grass. Look for sandy loam or silt loam soil with 2-5% organic content.
Compost Topdressing
Screened compost applied in a thin layer of 1/4 inch or less provides nutrients and organic matter evenly without excess moisture retention.
Core Aeration
Aerating reduces soil compaction and improves drainage and oxygen circulation. It should be done annually before seeding or fertilizing.
Gypsum
Applying gypsum can improve drainage in compacted, heavy clay soils. It allows better water penetration and root growth.
pH Adjusters
Sulfur lowers pH in alkaline soils while lime raises pH in acidic soils. This balances pH for optimal nutrient availability.
Fertilizer
The right fertilizer provides a tailored nutrient package for the needs of grass. Slow-release formulas prevent surge growth.
Overseeding
Seed spreads grass into thin or bare spots for a full, even lawn. Choosing quality seed ensures strong grass.
Conclusion
In summary, garden soil retains too much moisture, has overly high fertility, and its structure differs significantly from what lawn grasses prefer. While it can be incorporated sparingly into very poor soil, the results are usually better using soil blends and amendments designed specifically for lawns. With routine aeration, fertilization, overseeding and proper drainage, existing lawn soil can be transformed into an optimal growing environment for lush, healthy grass. Test your current lawn soil and make amendments tailored to create the ideal conditions grass needs.
