Do you want to know the best drainage material for potted plants?
A hot topic among gardeners is what to use for drainage in pots. Some materials, like rocks, won’t perform as you expect and can lead to confusion.
So, what planter drainage material is best?
Down below, I list the ideal options for planter drainage material, the pros and cons of each, and the best way to incorporate it in your pots.
Once you understand how each drainage material works, choosing the right option means you can watch your plants thrive instead of drowning!
Best Material For Drainage In Pots
With research showing many old-school recommendations don’t provide the drainage gardeners expect, it’s no wonder gardeners are hesitant to select a drainage method for potted plants.
To dispel some of the confusion surrounding common drainage material, I explain exactly how these top five perform inside your pots, so keep reading!
1. Quality Potting Mix
The best and easiest planter drainage material is a perfect soil blend.
Gardening professionals rely on specific potting soil mixtures that provide the right amount of moisture retention and drainage to grow plants with different watering needs.
Soil mixtures for succulents will be much different than potting soil for flowers.
- Avoids the need for additional pot drainage material
- Provides a blend of drainage and nutrients for better plant growth
- Easy to use straight from the bag – no extra work mixing
- Prevents soil compaction, which improves drainage and aeration
- Can be expensive, especially if you have an extensive container garden
- May not be practical if your pots already have soil inside you want to use
- The soil may still retain too much moisture for certain plants or inside specific planters
The consensus from experts is that filling a pot with a well-draining potting mix is the best choice if it works with your existing gardening system and your budget.
What about dirt falling through drainage holes?
If you are afraid dirt will leak from the drainage holes at the bottom of the pot when you water, cover them with a coffee filter or a piece of window screening. In reality, potting soil rarely falls out of drainage holes once the pot settles after the first watering.
Perlite is lightweight and has a low density, which increases soil drainage, yet holds up longer than more organic drainage material such as vermiculite or pine bark fines.
Perlite is a top choice for use as an additive to the soil you already have when drainage issues are drowning your plant’s roots.
- Lightweight, so pots are easier to move and lift
- Safe amendment for use in organic gardening
- Traps air, which increases soil oxygen levels and is beneficial to plant roots
- Prevents soil compaction, which increases drainage, air pockets, and encourages root development
- Retains some water, which releases back into dry soil to help maintain a consistent moisture level
- Will need to manually mix the material into existing soil, which can be messy
- Inhaling the dust can be harmful
- Does crush over time, which could become too dense and clog plant roots
For existing potting soils with poor drainage, adding perlite is a budget-friendly solution, but it will take plenty of manual labor to dump pots or bags of soil and mix in the perlite.
3. Gravel or Rocks
Every gardener has heard that adding a layer of rocks or gravel to the bottom of a pot is the perfect way to cover drainage holes to prevent soil fall-through and for letting the excess water drain from the soil above.
In reality, this notion has been proven false, as scientific research shows using coarse material at the bottom of planters causes water to stop flowing and collect on top, keeping the soil wet.
Too much water in soil quickly leads to root rot and dead plants, which confounds beginner gardeners who don’t know about this issue. So are there ways to improve soil drainage with gravel or rocks if that is all you have on hand?
- A layer of rocks on a planter bottom is fine if you perch another plastic pot (with drain holes) holding the soil and plant on top, which increases humidity at plant roots but keeps water draining
- Superfine gravel mixed throughout your potting soil improves aeration and drainage while reducing compaction
- Gravel is free or cheap
- A layer of gravel or rock at pot bottoms forms a barrier that prevents natural water drainage
- Increases overall weight of the pot, making it harder to lift and move
- Roots can’t grow into gravel, which can restrict root development
4. Activated Charcoal
Activated or horticultural charcoal is a material most gardeners never think of when it comes to drainage in planters. This material is even works well in pots that have no drainage holes at all, which is commonplace for indoor plants.
- Inexpensive to purchase and easy to use
- Absorbs excess moisture without getting soggy so that roots won’t rot
- Has natural antimicrobial action, which reduces fungal, disease, and pest issues
- Can be mixed into soil or used as a base layer
- Pulls harmful toxins from the soil or water, so plants are healthier
- Can be dusty – Good idea to use gloves and use in a well ventilated area
- Do not make the mistake of using grilling charcoal as a substitute (please don’t!)
Sand can amp up the drainage in pots with dense soil, mainly if you use dirt from your yard that has a high clay content. Use sand that is coarse in texture and not super-fine silica sand, which will only add to your drainage issues.
You need to be careful when using sand to increase drainage, as there is a wrong and right way to use it in potted planters.
- Inexpensive and readily available
- Loosens soil texture, which improves aeration and drainage
- The finer texture doesn’t create a water barrier like rocks or pottery shards as base of pots
- An inch or two at the bottom of a planter with no drain holes can lift roots out of pooling water
- Too much sand in the potting mixture can drain off water too fast, leaving plants thirsty
- Sand is heavy and may settle toward the bottom of the pot during watering, so yearly soil mixing is necessary
- Sand with a fine, rounded texture can inhibit drainage by filling in natural air gaps in soil
If you want to use sand as a base layer in pots, drill small drain holes about 1/2-inch up around the bottom perimeter of the pot.
Holes in this location keep enough moisture in the pot to bring humidity to the roots but allows excess water to drain out of the sand to prevent root rot.
Finding the best drainage material for potted plants is a combination of availability, cost, effectiveness, and ease of use.
As you now see, many materials can work to provide better drainage in pots, and when correctly put to use, they won’t cause harm to your plants.
No matter which method you try, good potted-plant drainage is the secret to gardening success!