Yes, you can plant a garden over a septic drain field, but you must do so with great care and follow specific guidelines. Planting correctly can help the system work well and make your yard look nice. Planting the wrong things, like trees or heavy shrubs, or doing heavy digging can damage the pipes and soil inside the drain field, leading to costly repairs. It’s important to pick the right Best plants for septic drain field areas and avoid Plants to avoid near septic systems.
Image Source: extension.unh.edu
Seeing How Septic Systems Work
Before you put plants over your septic area, it helps to know what’s down there. A septic system treats water that goes down your drains from your house (like sinks, toilets, showers). It has a tank and a drain field.
The Septic Tank
Dirty water flows into the septic tank. Solids sink to the bottom, forming sludge. Oils and grease float to the top, forming scum. The liquid water, called effluent, is in the middle. Bacteria in the tank help break down some of the waste.
The Drain Field
The effluent from the tank flows out into the drain field. The drain field is made of underground trenches, usually filled with gravel or stone, and a network of pipes. These pipes have holes in them. The liquid water slowly drips out of the pipes and into the soil and gravel. The soil then acts like a filter, cleaning the water before it goes back into the ground water.
The drain field needs to let water soak into the ground. This is why keeping the soil healthy and not squishing it down is key. Planting over it can help with this, but only if you do it right.
Why Planting Over It Matters
Putting plants over your drain field isn’t just about making things pretty. Plants can help in several ways:
- Preventing Soil Loss: Plant roots hold the soil together. This stops rain or melting snow from washing the soil away, which could uncover parts of the drain field or hurt the soil layers that filter water.
- Soaking Up Water: Plants use water from the soil. This helps the drain field work better by taking up some of the clean water that soaks out of the pipes. This is especially helpful in wet areas or during rainy times.
- Keeping Soil Loose: The activity of roots and small bugs in the soil can help keep it from getting too packed down. This lets air and water move freely, which is good for the filtering process.
- Making It Look Nice: Drain fields are not pretty to look at. Plants cover the area, making your yard look finished and cared for.
But if you plant the wrong things or plant the wrong way, you can cause big problems.
What Not to Do: Big Risks to Avoid
There are several things you absolutely should not do when Landscaping septic system area over the drain field. These things can break the system or stop it from working right.
Digging Too Deep
The pipes in the drain field are usually not too far below the ground surface. Digging deep holes for trees, big shrubs, or even some types of fencing can hit and break these pipes. Any digging over the drain field should be very shallow. Think inches, not feet.
Letting Roots Go Wild
This is one of the biggest problems. Deep roots near septic system pipes can find their way into the small holes where water comes out. Once inside, they grow bigger, blocking the pipes. This stops the water from draining, making it back up into your house or flood the yard. Trees and many shrubs have deep, strong roots that can cause major damage. This is why Trees near septic field are almost always a bad idea.
Squishing the Soil Down
The drain field works because the soil and gravel layers let water move through and filter it. If you put heavy things over the drain field, or if many people or cars pass over it, you can pack the soil down. This stops water from soaking in. Think about parking a car, building a shed, or even putting in a heavy stone path. These can hurt the system. Raised garden beds over septic can also be a problem if they are very large, heavy, or involve bringing in a lot of extra soil that adds too much weight and packs things down.
Planting Water-Loving Plants
Some plants, like willows or certain types of bushes, love wet soil and will send out many roots looking for water. The drain field is a place with extra water, so these plants are very attracted to it. Their roots can quickly invade and block the system. These are definitely Plants to avoid near septic systems.
Important Guidelines for Planting
To keep your septic system safe while making your yard look good, follow these Septic drain field planting guidelines. These rules help you pick the right plants and plant them correctly.
Know Where Your System Is
This is the first and most important step. You need a map of your septic system, especially the drain field area. If you don’t have one, check with your local health department. You can also hire a septic company to locate it for you. Mark the edges of the drain field clearly. Do not plant or do any digging outside of shallow cultivation within a certain distance of the tank or distribution box either, as these also have pipes and are sensitive areas.
Stay Shallow
All planting over the drain field must be shallow. This means plants with Shallow-rooted plants for septic are best. You should not dig deeply when planting. For most suitable plants, you only need to dig a small hole just big enough for the plant’s root ball. Adding a thin layer of mulch is okay, but avoid thick layers of new soil that could add weight.
Keep It Light
Avoid anything heavy over the drain field. This includes:
* Parking cars or other vehicles
* Building sheds, decks, or patios
* Putting in pools or hot tubs
* Heavy landscaping materials like large rocks or thick layers of topsoil.
* Big, heavy Raised garden beds over septic made of thick wood, stone, or concrete and filled with lots of soil. Small, lightweight beds might be okay on the edges of the field, but generally, it’s best to avoid them directly over the main area due to weight and soil disturbance.
Stick to the Right Plants
The type of plant matters most. You need plants that won’t send deep, strong roots down to the pipes. Groundcovers, grasses, and shallow-rooted perennial flowers are usually good choices. We will talk more about the Best plants for septic drain field soon.
Leave Room Around the Tank and Access Points
You need to leave easy access to your septic tank and any inspection ports or risers. Don’t plant right on top of these. Plant around them so they can be easily uncovered for regular checks and pumping. Usually, a few feet of clear space is needed.
No Vegetable Gardens
A Vegetable garden over septic drain field is generally not a good idea and is often against local rules. Here’s why:
* Many vegetables are annuals, meaning you have to dig and replant them every year. This repeated digging can disturb the soil and possibly hit pipes.
* Some vegetables, like corn or tomatoes, have deeper root systems than you might think.
* There is a small risk of vegetables taking up bacteria or viruses from the treated water in the drain field, although the soil usually filters these out. Still, it’s a health concern many experts warn against.
* The soil over a drain field might not be the best for growing food due to the mix of gravel and fill dirt used.
It is much safer to plant your vegetable garden in another part of your yard.
The Best Plants for Septic Areas
Choosing the right plants is key for successful Landscaping septic system area without harming the system. The goal is to pick Shallow-rooted plants for septic areas.
Here are some types of plants that generally work well over a septic drain field:
Grasses
Standard lawn grass is one of the best covers for a drain field. Its roots are very shallow, usually just a few inches deep. It helps prevent erosion and uses some water. You can mow it easily, and it requires no digging after it’s planted. Wildflowers mixed with grasses can also work, as long as they are shallow-rooted types.
- Pros: Very shallow roots, prevents erosion, uses water, easy to maintain (mowing).
- Cons: Needs regular mowing and watering (unless it’s a native, low-maintenance grass).
Groundcovers
Many types of groundcovers are excellent choices. They spread out sideways rather than sending deep roots down. They cover the soil, look nice, and help hold the ground in place.
- Examples: Creeping thyme, sedum (low-growing types), vinca (periwinkle), phlox (creeping varieties), some low-growing juniper types (check root depth), clover.
- Pros: Shallow roots, cover large areas, help with erosion, many are low-maintenance once set.
- Cons: Some can spread aggressively and might need managing.
Perennial Flowers (Shallow-Rooted)
Many perennial flowers have root systems that are not too deep. They come back every year and add color to your yard. Make sure to pick varieties known for having shallower roots. Avoid types that form large clumps with deep taproots or bulbs that need deep planting.
- Examples: Daylilies (check variety, some clump deeply), hostas (most varieties), astilbe, some types of coneflowers (Echinacea – check root depth), sedum (taller varieties), certain ornamental grasses (like fescue or some switchgrass varieties – again, check root depth and growth habit). Aim for fibrous root systems, not taproots.
- Pros: Add color and interest, shallow roots (if chosen carefully), come back each year.
- Cons: Need careful selection, some require dividing over time (which means shallow digging), can attract more bugs or require more care than grass.
Annual Flowers
Annuals live for just one growing season. You plant them from seed or small plants each year. Their roots are generally quite shallow since they don’t need to survive winter. The main risk is the yearly digging to plant them. If you plant them from small pots into small, shallow holes, the risk is lower than planting bulbs or large bedding plants that require deeper holes or soil turnover.
- Examples: Petunias, marigolds, impatiens, zinnias, cosmos.
- Pros: Many colors and options, roots are shallow for one season.
- Cons: Requires annual planting (shallow digging), don’t provide year-round cover.
Small Shrubs (With Caution)
Some very small, non-woody shrubs with clearly shallow, spreading root systems might be acceptable on the edges of the drain field or over inactive parts (like where the pipe from the tank enters, but not over the distribution area). However, this is risky, and it’s generally safer to avoid shrubs altogether over the main drain field area. If you consider one, research its root system thoroughly and plant it away from the most critical areas.
- Example: Certain low-growing junipers or spireas known for shallow, spreading roots (use extreme caution and check local rules).
- Pros: Can provide some structure or evergreen cover.
- Cons: Higher risk of root damage than grasses or groundcovers, harder to remove if roots become a problem, adds more weight/bulk.
Native Plants
Using native grasses and wildflowers that are suited to your local climate and soil type can be a good idea. They often require less water and fertilizer, which is good for the septic system. Make sure their root systems are shallow. Your local extension office can help you find Best plants for septic drain field options that are native to your area.
Table of Suitable Plant Types
| Plant Type | Root Depth | Maintenance | Septic Suitability | Notes |
|---|---|---|---|---|
| Lawn Grass | Very Shallow | Moderate (mowing) | Excellent | Standard choice, good erosion control |
| Groundcovers | Shallow/Spreading | Low to Moderate | Excellent | Good soil cover, many varieties |
| Perennial Flowers | Shallow (select) | Moderate (deadheading, dividing) | Good (with careful selection) | Add color, check root type (fibrous > taproot) |
| Annual Flowers | Shallow (1 yr) | High (yearly replant) | Fair (shallow planting) | Seasonal color, requires yearly shallow digging |
| Small Shrubs | Variable (riskier) | Moderate | Risky (use caution on edges only) | Avoid over main drain field |
| Native Plants | Variable (select) | Low (if well-suited) | Good (select shallow types) | Good for local environment, low water/fertilizer |
Plants to Absolutely Stay Away From
Knowing Plants to avoid near septic systems is just as important as knowing what to plant. These plants can seriously harm your drain field.
Trees
Any type of tree is a major risk. Trees near septic field areas are almost guaranteed to cause problems eventually. Tree roots are strong, deep, and spread far looking for water. The moist, nutrient-rich environment of a drain field is very attractive to them. Even if planted 20-30 feet away, roots can travel towards the drain field.
- Examples: Maple, oak, willow, poplar, cypress, fruit trees, evergreen trees. Any tree should be kept a significant distance away (ask a local expert for recommended setback distances, which can be 50-100 feet or more depending on the tree type and system design).
- Why Avoid: Deep roots near septic system pipes are the primary cause of blockages and system failure.
Large Shrubs
Similar to trees, large shrubs have extensive and often deep root systems. They can pose the same risk of root intrusion into pipes.
- Examples: Large hollies, rhododendrons, azaleas (some can have deep roots), some potentillas, thick hedges.
- Why Avoid: Roots can block pipes and add too much weight/bulk over the field.
Plants That Love Water
Plants that naturally grow in wet areas or are known to aggressively seek out water should be avoided near drain fields, even if their roots aren’t strictly “deep” like a tree’s. Their density and growth habit can still cause problems.
- Examples: Willows (mentioned under trees, but worth repeating as they are major water-seekers), some types of popular landscape bushes, cattails (obviously, but highlights the point), certain types of bamboo (aggressive spreaders).
- Why Avoid: They are highly attracted to the drain field and their roots can quickly proliferate and clog the system.
Plants Requiring Deep Soil Preparation
Avoid plants that need the soil turned over deeply before planting, or those that require adding a lot of heavy soil or compost. This disturbs the soil layers in the drain field that are designed for filtration and can compact the area.
Plants with Aggressive, Spreading Rhizomes or Taproots
Some plants spread underground very aggressively via rhizomes or have single, very deep main roots (taproots). These should be avoided.
- Examples: Running bamboos, sumac, some ornamental grasses with strong rhizomes, dandelions (while a weed, shows the concept of a taproot), some prairie plants not suitable for drain fields.
- Why Avoid: Rhizomes can form a dense mat that hinders water flow, and taproots go too deep.
Table of Plants to Avoid
| Plant Type | Root System | Septic Suitability | Why Avoid |
|---|---|---|---|
| Trees | Deep, strong, wide-spreading | Never | Deep roots near septic system cause blockages |
| Large Shrubs | Deep and/or dense | Avoid | Roots can clog pipes, too much weight |
| Water-Loving Plants | Aggressively seek water | Avoid | Attracted to drain field moisture, cause clogs |
| Deep-Rooted Perennials | Taproots or very deep clumps | Avoid | Roots go too deep |
| Aggressive Spreaders | Rhizomes or runners | Avoid | Can form dense mats, hinder water flow |
| Plants needing deep prep | Disturb soil, compact | Avoid | Damages filtration layers, compacts soil |
Specific Landscaping Choices
Let’s look closer at a few specific Landscaping septic system area ideas people often ask about.
Vegetable Garden Over Septic Drain Field
As mentioned before, this is generally not recommended.
* Reasons Against: Risk of damaging pipes during yearly planting, potential (though low) health risk from soil/water contact with food, soil composition might not be ideal for vegetables, adds weight/compaction risk.
* Alternative: Build your vegetable garden elsewhere in the yard, away from the septic system components.
Raised Garden Beds Over Septic
This is also usually discouraged, especially large or heavy ones.
* Reasons Against:
* The weight of the bed materials (wood, stone, concrete) and the soil added can compact the drain field soil below.
* Building the bed might require some ground leveling or digging, which is risky.
* The plants in the raised bed might still develop roots deep enough to reach the drain field pipes, especially if the bed is tall.
* It makes it harder to access the drain field for maintenance or repairs.
* Alternative: Stick to ground-level, shallow-rooted plants. If you want the look of a raised bed, consider building one next to the drain field area, not directly over it.
Paths and Patios
Hard surfaces like patios, decks, or even heavy stone paths should never be built directly over the drain field.
* Reasons Against:
* Compacts the soil severely, preventing water drainage.
* Prevents air circulation to the soil, which is needed for the system to work.
* Makes it impossible to access the drain field for maintenance or repair without destroying the hard surface.
* Adds significant weight.
* Alternative: Use grass or suitable groundcovers over the drain field. If you need a path nearby, build it around the drain field area, not across it. Lightweight mulch paths (like wood chips) might be acceptable if kept thin, but it’s safer to avoid anything that adds weight or prevents access.
Mulching
Applying a thin layer (1-2 inches) of lightweight mulch like wood chips or shredded bark over planted areas is usually acceptable.
* Benefits: Helps hold moisture, controls weeds, makes the area look neat.
* Caution: Do not use heavy mulches like gravel or stone. Do not apply very thick layers that could compact the soil or prevent air exchange.
Following Septic System Landscape Rules
Beyond plant selection, there are overall rules for Landscaping septic system area to keep in mind:
- Know Your System’s Location: Get a map, mark the area clearly.
- Respect Setback Distances: Keep certain distances from the tank, distribution box, and the drain field edges, especially for larger plants like shrubs (even small ones) and definitely for trees. Local rules vary, so check with your health department.
- Avoid Soil Compaction: No driving, parking, heavy equipment, or heavy structures over the drain field. Limit foot traffic if possible.
- Do Not Dig Deeply: All planting should be shallow cultivation for appropriate plants.
- Maintain Access: Keep access points to the tank and drain field clear for inspections and pumping.
- Direct Surface Water Away: Make sure rain gutters and downspouts drain away from the drain field area. Too much extra water flooding the area can make the drain field less effective or fail.
- Avoid Extra Irrigation: The drain field provides moisture. Overwatering planted areas can saturate the soil too much, hurting the system’s ability to drain. Choose plants that don’t need much extra water.
- Limit Fertilizer and Chemicals: Use fertilizers and pesticides sparingly, or not at all, over the drain field. These chemicals can end up in the groundwater.
The Benefits of Doing it Right
When you follow the guidelines and choose the Best plants for septic drain field areas, there are real benefits:
- A Better Looking Yard: You can turn a hidden, unused area into a pleasant part of your landscape.
- System Protection: The right plants and proper Landscaping septic system area practices protect the drain field from erosion and compaction.
- Improved System Function: Plant roots help use some of the water, which can be good for the system, especially in wetter climates.
- Easier Maintenance: A well-planted drain field area is often easier to maintain than bare soil or an area with weeds.
- Environmental Health: Keeping the system working well protects local groundwater.
It’s a balancing act: use the space, but treat the underground system with respect.
Deciphering Soil Over the Drain Field
The soil over a drain field might be different from the rest of your yard. Often, the original topsoil is removed when the system is put in, and fill dirt, gravel, and possibly some replacement topsoil are used. This can mean the soil is less fertile or has a different texture than you’re used to.
- Soil Type: It might be compacted fill, sandy, or have a lot of gravel mixed in. This affects what grows well.
- Moisture: The soil directly over the drain field pipes might be wetter than surrounding areas, especially at certain times.
- Nutrients: The treated water contains some nutrients, which can make plants right over the pipes grow faster or look greener – sometimes indicating where the pipes are!
Because the soil can be variable and potentially less ideal for gardening, choosing hardy, less demanding plants like native grasses or groundcovers is often the safest and most successful approach. Trying to amend the soil heavily (adding lots of compost, tilling) is risky due to the need to keep digging shallow.
Long-Term View: Maintenance and Monitoring
Once your drain field is planted, ongoing care is needed.
- Regular Checks: Keep an eye on the area. Look for signs of wetness, soggy spots, or strange odors, which could mean the system isn’t draining right.
- Plant Health: Make sure your chosen plants are doing well. If plants start struggling in one area, it might signal a problem underground.
- Root Management: Even with recommended plants, keep an eye on their growth. If any plant starts showing signs of getting too big or seems overly vigorous right over the lines, be prepared to trim it back or replace it with something else.
- Septic System Pumping: Remember that regular pumping of your septic tank (usually every 3-5 years for a typical home) is vital for the system’s health, regardless of what’s planted above it. The pumpers will need clear access to the tank lids.
By paying attention and sticking to the rules, you can have a functional septic system and a beautiful, planted yard space.
Frequently Asked Questions About Planting Over Septic Fields
Can I plant flowers over my septic drain field?
Yes, many types of shallow-rooted perennial and annual flowers are suitable. Choose varieties that do not have deep taproots and plant them using shallow methods. Avoid flowers that require significant soil disturbance or deep planting.
Are there specific grasses that are best for a septic field?
Standard lawn grasses like fescue or bluegrass are excellent because their roots are very shallow. Native grasses with shallow, fibrous root systems are also a good choice, often requiring less water.
How far away should trees be planted from a septic field?
The recommended distance varies depending on the tree species and local regulations, but it is often between 50 to 100 feet or more. Tree roots are a major threat to septic systems.
Can I put mulch over my septic drain field?
A thin layer (1-2 inches) of lightweight organic mulch (like wood chips or shredded bark) is generally acceptable. It helps retain moisture and suppress weeds. Avoid heavy mulches like gravel or stone, and don’t apply thick layers that could compact the soil.
Is it okay to walk on the septic drain field after planting?
Occasional foot traffic is usually fine, but avoid heavy or frequent foot traffic, and absolutely no driving or parking vehicles on the drain field. Soil compaction harms the system.
What are the signs that roots might be damaging my septic system?
Signs can include slow drains in your house, toilets backing up, soggy or overly wet areas in the drain field when it hasn’t rained much, sewage odors, or unusually lush, fast plant growth directly over the pipe lines (indicating roots have found the water source).
Do I need to tell landscaping companies about my septic field?
Absolutely yes. Always inform anyone doing work in your yard, including landscapers, fence installers, or anyone digging, about the location of your septic system and drain field. Provide them with a map if possible.
Can I build a fence over or right next to the septic drain field?
Building a fence requires digging post holes, which can damage the pipes or soil layers. Avoid building fences directly over the drain field. Build fences around the area, respecting recommended setback distances.
Summing It Up
Planting over a septic drain field is possible and can be beneficial for your yard and the system’s health. The key is careful planning, knowing exactly where the system is, and strictly choosing Shallow-rooted plants for septic areas while avoiding Plants to avoid near septic systems like trees and large shrubs. Follow Septic system landscape rules regarding digging, weight, and access. While you can create a beautiful space, forget about Vegetable garden over septic drain field and Raised garden beds over septic, as these pose too much risk. By selecting the Best plants for septic drain field and following guidelines, you can have a landscape that is both attractive and protective of your vital septic system.