Plants for Septic Tile Fields

Septics and Tile Beds are a hot topic in Cottage Country.

Some waterfront properties are large enough and flat enough with appropriate setback from the water’s edge for a full septic and tile bed system.  Some are limited in footprint, or it is an older structure that is too close to the water, and can only accommodate holding tank.   If a holding tank is placed on grade and back-filled creating a new ‘mound’ on the property, erosion and wash-out of the imported fill can be a big problem, requiring multiple re-visits by the contractor.  Either way, the process of installing or repairing a septic system is, truthfully destructive, exposing mineral soil, which is a perfect invite for invasive species*.  Therefore, septic system fields require diligent maintenance to prevent nature, and invasives, from moving back onto the system, because that’s what they need to be – fields.

Why don’t we want the forest to move back to the areas we’ve cleared for our effluent management?  Well, the below-ground plumbing cannot be shifted.  Pipes and clay tiles, drainage gravel; they  are all required to stay put and function well for as long as they can for a good return on investment.  Tree and shrub roots, being woody, are known to fracture even the most impressive rock-faces, let alone foundations, concrete pools, and other man-made structures.  Woody roots punch holes and grow ever larger, which is great for porosity and soil health, and they hold shorelines in place and prevent erosion, but they just don’t cooperate with infrastructure stability, which humans require.  It is best to treat septic fields as just that – fields and meadows, whether in the shade or sun, they need to be culturally maintained areas.

It is recommended to regularly maintain one’s tile bed area by pulling out newly established trees and shrubs, pretty much on an annual basis.  The forest ALWAYS wants to return with the help of all of the little critters burying their caches and pooping out forest seeds.

Raspberries and blackberries are usually the first pioneers, followed by cherries, poplars and of course, Sugar maples.  We spend a lot of our client time pulling plants out of septic beds.  So how can we make it easier on ourselves?  How can we make it more difficult for raspberries and blackberries to establish?

Planting groundcovers and wildflowers with shallow, running roots is a good way to start.  These plants won’t completely prevent the establishment of woody roots, but they will make it more difficult for woody-species’ seeds to hit mineral soil.   The faster one can re-establish vegetation upon disturbed soil, the more efficient the vegetation will be at keeping the woody-species seeds from hitting soil. So, which groundcovers are not invasive (like Vinca minor), and which are indigenous to the area?  Which are best for sunny tile beds and which are best for shade?  There are some taller wildflowers that have shallow root habit, but many tile beds are part of a ‘vista’ system, where tall species are not wanted, and then there is of course turf, which can be maintained and kept at a low height by mowing.

Planting your tile field, along with planting your waterfront with a buffer of indigenous deep-rooting woody species (there are many low-growing woody species which put down good roots) will help keep your lake healthy and you and your neighbours, wild and human, happy.

*Please be sure to request that your contractor clean and pressure-wash their heavy equipment in their yard before bringing it onto your site.  Heavy equipment and their tracks and ‘teeth’ hold many an invasive species in among their metal parts and are one of the main culprits in the transport of vegetative invasives.


N.B. Many of the following species will do a sufficient job covering a part-shade tile bed as well.  They can all be found in Central Ontario.

Barren strawberry (Waldstenia fragarioides)


Canada anenome (Anenome canadensis)

Canada Anemone June 2016 039.jpg

Large-leaved aster (Aster macrophyllus)


Bracken Fern (Pteridium aqualinium)

Jewelweed (Impatiens repens) and Boneset (Eupatorium perfoliatum)


Wild columbine (Aquilegia canadensis)

Hawkweed (Hieracium aurantiacum)



R.K. Blue-eyed grass IMG_3531.jpg

Black-eyed susan


A new tile bed with disturbed soil is a perfect opportunity to establish Fireweed.


and Common milkweed, which will return annually for Monarch butterflies.

R.K. Milkweed with Monarch caterpillar.jpg


N.B. Many of the following species will do well on a part-sun tile bed as well.  They can all be found in Central Ontario.

Wild geranium (Geranium maculatum)

Foamflower (Tiarella cordifolia)


Bunchberry (Cornus canadensis)

R.K. Bunchberry colony IMG_9732.jpg

Wild Columbine (Aquilegia canadensis)

Hay-scented fern (Dennstaedtia punctilobula)

Sensitive fern (Oenoclea sensibilis) with Joe Pye weed (not for septics)


Christmas fern (Polystichum acrostichoides)

Christmas fern June 2016.jpg

Wild Bergamont (Monarda fistulosa)

Wild bergamot 062.jpg

Rough woodland sunflower (Helianthus divericatus)Rough woodland sunflower IMG_1102.jpg












Solomon’s seal

R.K. Solomon's Seal IMG_3688.jpg

False solomon’s seal

R.K. False Solomon's Seal 1 IMG_3685.jpg


Bugleweed (Ajuga reptans)

Columbine cultivars (Aquilegia spp.)

Bee balm (Monarda didyma)

Bee Balm August 2016 008.jpg

…and then there are always those running mints and oregano, but I wouldn’t use them for food if you use chemical cleaners or bleach…

There will be more photos to come.

May the forest be with you.



  1. Rick Gray says:

    Great plant list, all except Hieracium aurantiacum (Hawkweed), which is native to Europe, not to Ontario.


  2. Jean says:

    Some great native Ontario plant suggestions until you got to Bugleweed, which is very invasive. I wouldn’t plant this anywhere in Ontario, but if I had to, it would be in a container, and certainly not in the country where it could get out of control.


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