Best Plants for a Septic Tank Disposal Field
When it comes to managing septic tank waste effectively, the design of the disposal field is crucial. A well-designed field not only ensures that the septic system functions properly but also provides an opportunity to create a thriving, green landscape that benefits the environment. One of the best ways to enhance your disposal field is by planting vegetation that can absorb moisture, suppress odours, and contribute to a healthier ecosystem.
If you’ve recently installed a septic tank on your lifestyle block or rural property, you may be wondering what to plant in your disposal field. This is a common question we receive, and we completely understand the uncertainty. Many property owners are keen to move beyond the practical installation phase and start enhancing the aesthetic appeal of their land. However, choosing the right plants can be a challenge, especially if you're not sure which species will thrive in these conditions. Fortunately, we have a list of tried-and-tested plants that are well-suited for septic fields.
Why Planting is Essential in a Septic Field
Septic disposal fields distribute treated wastewater (or greywater) through a network of driplines, allowing it to be absorbed by the surrounding soil. While this system is effective, planting the right vegetation in this area provides several additional benefits:
- Moisture Absorption: Certain plant species have the ability to soak up excess water, helping to prevent boggy, waterlogged conditions.
- Odour Control: Plants can act as natural air purifiers, reducing any potential odours emanating from the disposal field.
- Erosion Prevention: A well-planted disposal field prevents soil erosion, particularly in areas prone to heavy rain.
- Carbon Sequestration: By planting vegetation, you can create a small carbon sink, absorbing carbon dioxide and contributing to a greener environment.
- Biodiversity Support: Native plants attract birds, insects, and other wildlife, supporting the local ecosystem.
Best Native Plants for a Septic Field
The following plant species have proven to be highly effective in septic tank disposal fields. These plants thrive in wet conditions and have root systems that won’t interfere with the driplines:
1. Apodasmia similis (Oioi)
Oioi is a hardy wetland plant that grows well in damp and boggy conditions. Its fine, reed-like foliage adds a soft texture to the landscape, and it helps to absorb excess moisture effectively.
2. Austroderia richardii (Toe Toe)
Toe Toe is a tall, native grass that thrives in damp areas. It provides excellent windbreaks and adds height and movement to the landscape.
3. Carex secta / Carex virgata (Carex species)
These hardy sedges are ideal for wet soils, providing excellent water absorption. They also create dense ground cover, preventing erosion.
4. Coprosma propinqua
A compact, native shrub with small leaves and a tidy growth habit. It is an excellent choice for creating a structured look in a septic field while also providing shelter for birds.
5. Coprosma 'lobster'
This resilient plant features striking foliage and a low-maintenance growth habit, making it an excellent addition to the disposal field.
6. Cordyline australis (Cabbage Tree / Tī Kōuka)
One of the most iconic New Zealand native trees, the cabbage tree thrives in wet soil and has a shallow, non-invasive root system. Its striking form adds visual interest.
7. Dacrycarpus dacrydioides (Kahikatea)
A tall, slender tree well adapted to wet conditions. While it grows to impressive heights in the wild, careful placement in the septic field ensures it won’t interfere with structures.
8. Juncus edgariae (Wiwi / Native Rushes)
This native rush is perfect for areas with poor drainage, as it absorbs large amounts of water while adding a natural, grassy aesthetic to the landscape.
9. Phormium tenax (Flax / Harakeke)
Flax is a staple in wetland restoration projects, as it tolerates wet conditions and provides a bold, architectural presence in the landscape.
10. Plagianthus regius (Swamp Ribbonwood)
A fast-growing tree with a light, airy canopy, Swamp Ribbonwood is ideal for adding vertical interest while remaining suitable for wet soils.
Key Considerations When Planting a Septic Field
Before planting, it’s essential to consider a few practical aspects to ensure the success of your septic field landscaping.
1. Aesthetic Appeal
While functionality is key, you also want your septic field to look attractive. A good approach is to limit the number of species used and focus on creating a balanced composition of heights and textures. Grouping similar plants together and layering different heights can create a visually pleasing effect.
2. Animal Safety
If livestock or pets have access to the disposal field, it’s essential to choose non-toxic plants. Alternatively, fencing off the area can protect both the plants and your animals.
3. Height Restrictions
If the disposal field is near power lines, buildings, or areas where excessive shading could be a problem, consider choosing lower-growing species. Ensure that trees won’t interfere with structures or utilities as they mature.
4. Spacing and Plant Density
Proper spacing ensures that plants have enough room to establish themselves while providing good coverage. As a general rule, aim for one plant per square metre. For example, a disposal field measuring 30m x 3m would require approximately 90 plants.
5. Maintenance Requirements
While native plants generally require less maintenance, occasional weeding, mulching, and trimming may be necessary to keep the area tidy and thriving.
Common Mistakes to Avoid
- Planting Trees with Large Root Systems: Trees with deep or invasive roots, such as willows or poplars, can damage the dripline system and should be avoided.
- Overcrowding: While dense planting is good, excessive crowding can lead to competition for nutrients and airflow issues, leading to plant health problems.
- Neglecting Initial Care: Newly planted seedlings need a bit of extra care, including watering during dry spells and occasional fertilisation.
- Using Non-Native Species: While some exotic plants may survive in wet soil, native plants are better suited to local conditions and provide greater ecological benefits.
Conclusion
Planting your septic field with the right vegetation is a win-win situation—it helps manage wastewater efficiently, enhances the visual appeal of your property, and contributes positively to the environment. By choosing native plants that thrive in wet conditions and have non-invasive root systems, you can create a low-maintenance, functional, and beautiful landscape.
If you’re unsure about which plants will work best for your septic field, feel free to reach out. We’re always happy to provide expert advice and help you select the perfect plants for your property!