If you’re a passionate flower gardener, then having healthy soil drainage is essential for your plants to thrive. But what happens when the water doesn’t seem to drain properly? How can you improve soil drainage and create solutions for waterlogged gardens?
In this article, we discuss how to identify poor soil drainage, we show you ways of improving it, and we share maintenance tips that will help keep your garden in top condition.
What Happens if your Soil is not Draining Properly?
Poor soil drainage can have several consequences for your garden. Waterlogging is the primary one: if your soil doesn’t drain well, excess water tends to accumulate in the root zone of plants. Waterlogged soil can weaken the plants and make them more susceptible to diseases and pests.
Other consequences of poor soil drainage include:
- Root rot: Constantly wet soil creates a favorable environment for pathogens, particularly fungi, that cause root rot. This can cause the roots to decay, resulting in stunted growth, yellowing of leaves, and eventual death of the plant.
- Nutrient imbalance: Poor drainage can affect nutrient availability in the soil. Excess water can leach away essential nutrients, making them inaccessible to plants. On the other hand, certain nutrients may become concentrated in waterlogged areas, leading to toxicity issues. This imbalance can impair plant growth and development.
- Disease and pest problems: Poorly drained soil creates an environment that can encourage pathogens and pests that can damage plant foliage. Fungal diseases, such as damping-off, powdery mildew, and downy mildew, thrive in damp conditions. Bacterial wilts and blights require moisture and humidity to grow and spread. Certain pests, like slugs and snails, are attracted to moist environments.
- Reduced oxygen: Oxygen is crucial for root development and overall plant health. When the oxygen supply to the roots is limited, plants may exhibit stunted growth, wilted leaves, and overall poor vigor.
- Increased Salinity: Waterlogged soil can contribute to the buildup of salts in the root zone. As the water evaporates, it leaves behind salt deposits that accumulate over time. Elevated soil salinity levels can inhibit water uptake by plants, leading to dehydration and leaf scorch.
- Erosion: Excess water can wash away topsoil, which is rich in nutrients and vital for plant growth. This erosion can weaken the soil structure and make it more challenging for plants to establish strong root systems.
To address these consequences, you can improve soil drainage with an appropriate gardening technique such as adding organic matter, using raised beds, incorporating drainage systems, or selecting plants suited to your soil type can significantly enhance your garden’s health and productivity.
Signs of Poor Soil Drainage
The most obvious sign that you have poor soil drainage is if puddles form on top of the ground after a heavy rain or watering session.
Another symptom that suggests the soil is too saturated for your plants to access oxygen, is if your plants appear wilted and droopy even with sufficient hydration.
If you notice either of these signs in your garden, it’s time to investigate further.
Causes of Poor Soil Drainage
There are several possible causes for poor soil drainage.
Soil type: Clay-based soils in particular tend to retain moisture more than sandy soils do because they have smaller particles that don’t allow air and water to move through them easily.
Compacted soils: Soil compaction inhibits proper drainage since there isn’t much room for air and water movement between soil particles when the space has been compressed by compaction. This can happen when your garden area was previously used as a road, car parking, or if you’ve had any work done on your home or property that involved large heavy equipment.
Overwatered soil: While overwatering your garden or excessive rainfall are not in themselves causes of poor drainage, they lead to waterlogged soils. If heavy rainfall is a regular occurrence in your area, you will need to take appropriate measures for water management.
If your home and garden lie above a hardpan or an impervious subsoil, even though the topsoil may seem sufficiently drained, the layers of compacted soil underneath will not allow water to infiltrate, leading to a waterlogged garden.
Solutions for a Poorly Drained and Waterlogged Garden
Aerating the Soil
Making perforations in the soil can facilitate air and moisture flow, which facilitates loosening of compacted earth to improve drainage. This helps reduce compaction, which can cause poor drainage.
To aerate your soil, use a garden fork or spade to dig deep into the ground and create small pockets of air. Make sure you go at least six inches down for best results.
In more serious cases, or if you have a large area to aerate, you may want to hire a professional with special aeration equipment that can spike or plug the soil surface or break through the hardpan layer underneath your garden.
Soil Amendments that Improve Soil Drainage
When planting or amending your soil, choose soil mixes that have good drainage properties. Sandy loam or loamy soil types are generally well-draining, while heavy clay soils tend to retain water.
Adding organic matter such as compost, well-rotted manure, leaf mold, peat moss, and other materials will help improve soil drainage by providing additional nutrients and increasing porosity of the soil.
Compost helps retain moisture while still allowing excess water to drain away quickly so that roots don’t become waterlogged and deprived of the oxygen supply needed for healthy root growth. Manure also provides an excellent source of nitrogen which encourages root development, further aiding with better drainage capabilities.
Mix organic matter into the top few inches of the soil to encourage better drainage, improve soil texture, and allow water to flow more freely.
Applying a layer of organic mulch around your plants can also help improve drainage. Mulch reduces surface runoff, slows evaporation, and prevents soil compaction caused by heavy rains. Use materials like wood chips, straw, or shredded leaves, and maintain an appropriate thickness of mulch to allow the water to penetrate your soil.
Improving Water Management in Your Garden
Grade the Landscape to Improve Drainage
Adjusting the slope and grading of your garden can encourage proper water runoff. Ensure that the land slopes away from your garden beds to prevent water from pooling around plants. Be cautious not to redirect water towards neighboring properties or sensitive areas.
Retaining walls or terraces are another technique that allows water to percolate steadily rather than rush in a stream that immediately pools at the base of a slope.
Install Drainage Systems
In areas with severe drainage problems, installing drainage systems can be an effective solution. French drains, perforated pipes, swales, or underground drainage tiles can help divert excess water away from the garden. Drainage systems allow surface runoff from heavy rains or irrigation systems to be diverted away from areas where plants may struggle in waterlogged soils.
Swales are shallow, broad, and typically elongated channels or depressions in the landscape designed to manage water runoff. They are commonly used in landscaping, permaculture, and ecological design to help control and manage water flow on properties.
Both trenches and swales should have sloping sides so that gravity can help move the water downhill when needed.
Make a Gravel Garden
Gravel gardens are another method for growing a beautiful garden, even when you are dealing with poor soil drainage. Gravel gardens are a popular way to create an attractive garden in areas that are prone to seasonal drought, however, they are also useful when excessive water is a problem. Gravel allows water to drain quickly through the gaps between the rocks. This feature is particularly useful in areas with heavy rainfall or where the soil has poor drainage. By promoting efficient drainage, gravel prevents water from pooling or stagnating, reducing the risk of overwatering and root rot.
Gravel can also help facilitate water infiltration into the soil. When rainwater or irrigation is applied to a gravel garden, it can permeate the gaps between the rocks and gradually seep into the underlying soil layers. This process promotes deep root growth and encourages plants to access moisture from lower soil levels. By encouraging water infiltration, gravel gardening reduces surface runoff, which can lead to water wastage.
Plant a Rain Garden
Rain gardens are a way to work in cooperation with your existing soil, terrain, and areas where water naturally pools. A rain garden is simply a low-lying patch situated to collect storm water runoff from driveways, walks, roofs and other impermeable surfaces—run off that might otherwise end up in pristine wetlands, rivers and lakes.
The strong roots of water-loving rain garden plants also hold drenched soil in place, preventing erosion and filtering out pollutants before the runoff enters the groundwater. A rain garden allows you to take a problem spot and transform it into a miniature wetland filled with color and wildlife!
Build Raised Garden Beds
If your garden has heavy clay soil or if it experiences frequent waterlogging, raising your garden beds above ground level can be a game changer.
Raised beds elevate the planting area, providing better drainage and preventing water from accumulating around plant roots. Fill the beds with a good quality, well-draining soil mixture for the best results.
Container gardening could be a simple solution for some. While growing plants in containers will not fix soil drainage issues in your garden, it allows you to have beautiful and thriving plants, even if your garden becomes waterlogged.
Selecting Plants that Thrive in Poorly Drained Soil
Choosing plant species that do well in wet conditions not only ensures their survival, but it can also help to improve water drainage over time. While many plants dislike wet conditions and cannot survive in waterlogged soils, the following plants usually do well in these situations:
Marsh Marigold (Caltha palustris)
Marsh marigold is a perennial that thrives in wet soil and is often found near ponds or streams. It produces bright yellow flowers in early spring. This is not the same as the popular annual marigold (Tagetes species).
Virginia Bluebell (Mertensia virginica)
This charming spring-blooming perennial tolerates moist soil and partial shade. Virginia bluebell gets its name from its clusters of bell-shaped, blue flowers.
Siberian Iris (Iris sibirica)
Siberian iris is a hardy perennial iris species that can tolerate moist soil. They produce elegant, colorful flowers in early summer.
Joe Pye Weed (Eupatorium purpureum):
Joe Pye Weed is an exceptionally tall perennial plant that prefers moist to wet soil and produces large, mauve-pink flower clusters in late summer. It attracts butterflies and pollinators.
Sweet Flag (Acorus calamus)
Sweet flag is a grass-like perennial that thrives in wet or boggy soil. It has aromatic leaves and can be grown in water gardens or around ponds.
Ligularia (Ligularia spp.)
The large, attractive leaves of Ligularia make a bold statement for locations with moist soil and partial shade. They produce clusters of yellow or orange flowers in summer.
Cardinal Flower (Lobelia x speciosa)
Hummingbirds and butterflies love the tall spikes of red flowers produced by cardinal flower in late summer. This is a moisture-loving perennial.
Many fern species are adapted to moist and shady conditions. They can tolerate poor drainage and add a lush, textural element to the garden. Examples include ostrich ferns (Matteuccia struthiopteris) and lady ferns (Athyrium filix-femina).
Canna lily (Canna spp.)
Canna lily thrives in moist to wet soil conditions. They produce vibrant, tropical-looking flowers and add a dramatic touch to the garden.
Japanese Iris (Iris ensata)
Another iris known for its tolerance of wet soils. Japanese iris produce large, showy flowers in various colors that create an artistic feel in the garden.
Remember to consider other factors such as sunlight exposure and your region’s hardiness zone when selecting plants for your garden.
Planting cover crops is also an effective way to maintain healthy soil drainage while also improving fertility levels in the long run. Cover crops such as clover or buckwheat act like green manure by adding organic matter back into the soil while preventing erosion and compaction due to their deep root systems which penetrate deeper than other crop varieties do.
Maintenance Tips for Healthy Soil Drainage
Once you’ve made the effort to improve soil drainage, you’ll want to keep it that way. Follow these tips to help maintain good soil drainage in established areas:
- Good watering practices can help keep poor drainage issues in check. Water your garden deeply but less frequently to encourage deep root growth and prevent water from sitting on the surface. Make sure you’re watering your plants only when necessary and use a soaker hose or drip irrigation system instead of sprinklers if possible.
- Monitor the moisture level of the soil and adjust your watering accordingly, taking into account rainfall and specific plant requirements. Check the soil before each watering session with your finger or a trowel – if it feels damp, then skip that day’s watering.
- Mulching regularly is one of the most important maintenance tips for healthy soil drainage. Mulch helps to reduce evaporation, retain moisture, and keep weeds at bay. It also helps to improve soil structure by providing organic matter that breaks down over time. The best mulches are those made from natural materials such as bark chips, wood chips, straw, or shredded leaves. These materials help to absorb excess water and can be easily replenished when needed.
Moving water is the most prominent cause of soil erosion. If your soil drainage problems are resulting in erosion you’ll want to investigate the remedies found in our article, How to Stop Soil Erosion.