Selecting planter liners with the features your project requires will save you time, money, and effort.
Major considerations when selecting planter liners are the shape of the planter, the material the liner is constructed with, the location of drain(s), and size relative to your landscaping requirements.
- Selecting planter liners with a shape tapering to a smaller base makes for repotting slip-out easy and if they stack then you save money shipping.
- Rugged commercial grade 3/16″ walls from UV-stable, 100% pre-consumer recycled low-density polyethylene, or polypropylene are both flexible and food-safe, they will last decades in the sun and unburden landfills as they are recyclable materials.
- Side wall, not bottom drain, aids drainage. Is the drain threaded for proper drainage systems accessories if required by your 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.
- Liner depth is determined by the requirement of the plants you have selected.
An important consideration to successful landscaping in planters is starting with the right soil mixture and drainage for your plants.
- You want your container to drain well while retaining moisture but not hold water. Do not use “dirt” or any material with clay which will block drains. Perlite is a good light weight additive if your trying to improve quick drainage, Vermiculite if your trying to retain moisture. Very course sand, like commercially available “paver base” if you need weight to prevent toppling in high winds but not fine “beach” or “mortar” sand as they will immediately block your drains. Remember many plants have specific soil PH needs.
- 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 are placed 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. When selecting planter liners pick one with sidewall drainage, not on the bottom. This is an integral part of the drainage system as it allows the “fines” to settle to the bottom below the sidewall drain. 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. There is no need to put rocks or gravel in the bottom of a plastic pot, it only raises the water table.
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. We have had good results here in Florida with “rubber mulch”, but then we can get 6″ of rain in one day.
“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. Rubber mulch may also work for you.
For more detailed information on drainage see this related post: