DeepStream’s advice for garden planter liners & planting containers
1st Consideration: Liner shape and drain placement
- Tapered shape makes for easy repotting and saves money shipping.
- Rugged commercial grade 3/16″ walls from UV-stable, 100% pre-consumer recycled low-density polyethylene will last decades and unburden landfills.
- Side wall, not bottom drain, aids drainage and is threaded for proper drainage and drainage systems accessories required by some locations.
- There is a water reservoir below the drain for the tap root while providing a place for “fines” or clay to settle to prevent drain blockage.
The second step in drainage is starting with the right soil mixture
- You want your container to drain well and be moist but not hold water, do not use “dirt” and any material with clay which will block drains. Perlite is a good light weight additive as is very coarse sand if you need weight to prevent toppling in high winds but not fine “beach” or “mortar” sand.
The third consideration is filtration and root blockage
- geo-textile fabric and drain board to provide filtration and space over drain.
- BioBarrier (TM) with a plastic-embedded non-systemic herbicide, with a lower toxicity than table salt or aspirin, that creates a 2″ thick root deflection zone around the drainage material by preventing root cell tip division. The product, guaranteed effective for 15 years, has been used as a weed control system for more than 35 years in agriculture to prevent weed growth between row crops. Drainage pads place it over the drain hole.
- To prevent clogging you need to slow the water so that the fines in the planting medium settle to the bottom and not onto the filter medium. This is an integral part of the drainage system. Traditional pea gravel is too large and the water will flow rapidly to the drain and clog it with fines. Fine sand will flow too slow and form an impenetrable layer clogging with fines.
It is best to use a 2 to 4 inch thick covering of very clean, very coarse sand of between 1 and 2 mm particle size mounded over the drain filter. For reference, the wire of a medium paper clip is 1 mm. “Paver Base” is an acceptable readily available alternative from most large home improvement stores and will work in our planter liners with a side drain as the well below it provides a place for fines to settle.