By: Becca Badgett, Co-author of How to Grow an EMERGENCY Garden
Containers for holding our plants become more unique with each new planting. Anything goes these days for use as a planter; we may use cups, jars, boxes, and baskets– anything that has that perfect look to hold our plants. Sometimes we find the perfect planter without drainage holes.
While all plants need some water for survival, having suitable drainage is important to prevent root rot. For this reason, you need to add a few holes for potted plants so the water can escape. It’s not complicated if you follow basic instructions and precautionary measures when drilling a drainage hole. (Always wear protective eye-wear when using a drill.)
Adding Drainage Holes to Containers
Plastic and wood planters are among the easiest to fit with drainage holes. Sometimes punching holes in planters can be accomplished with a nail. Another interesting tool that some people use for drilling a drainage hole is a rotary tool often referred to as a Dremel.
A simple electric drill, properly fitted with the right bit, can add the necessary holes in the bottom of a container. Some say a cordless drill works best and allows the user more control. Drill slowly and steadily. You’ll want to apply little pressure and hold the drill straight. Sources recommend starting with ¼-inch (6 mm.) bit, moving up to a larger size if needed.
Water, in abundance, is on the tool list for this project. Water keeps the drill bit and the drilling surface cool. This makes drilling a drainage hole move a little more quickly. If you have a DIY friend, perhaps he or she can spray the water for you. Do this project outside and use the garden hose. Keep water on the drilling surface and the drill bit, as this is a crucial part of the process. If you see smoke, you need more water.
Experts at adding drainage holes to containers agree that you should mark the hole spot on the planter, either with a pencil on clay pots, a nick from a nail, or the drill on harder to drill pieces. On ceramics, mark the spot with a ding from a smaller drill bit. Many also suggest marking the area with masking tape first, saying it keeps the drill from slipping.
Then, hold the drill straight toward the pot, don’t put it in at an angle. Hold the drill straight as you spray the water on the surface. Start at low speed. Guide the drill and don’t apply pressure. Hopefully, you’ll get just the hole you need on the first try, but you may need to increase the size of the bit. These instructions apply to all materials.
The difference is the type of drill bit you’ll want to use. Some drills come with a selection of bits, and with others you’ll need to purchase a kit. On the list below, notice that some materials require a diamond tipped drill bit. This is called a hole-saw and spreads the pressure evenly, decreasing the possibility of shattering your container. The following bits are preferred by professionals:
- Plastic: Sharp twist bit
- Metal: Ultra-durable cobalt steel bit
- Unglazed Terra Cotta: Soak overnight in water then use a tile bit, a diamond grinder bit, or a Dremel tool
- Glazed Terra Cotta: Diamond tipped tile bit
- Thick glass: Glass and tile drill bits
- Ceramics: Diamond drill bit or a masonry bit with a winged tungsten-carbide tip
- Hypertufa: Masonry bit
This article was last updated on
Read more about Container Gardens
Whether your potted plants are indoors or outdoors, proper drainage is an essential element to ensure they stay healthy. This process keeps water from pooling at the base of the pot, which can cause bacteria, fungus and root rot.
If you find that your favorite pot doesn’t have a hole in the bottom for drainage, we have good news: almost any container can become a happy home for a plant! We’re going to show you how your favorites can stay healthy, no matter the vessel.
We chose this glass jar for a small Swedish ivy plant. We wanted to use a clear container for our example so that you can easily see the layers throughout the process.
+ A container or pot
+ Landscape rocks—we used gray marble rocks
+ Horticultural charcoal
+ Potting soil
These items can all be found at your local greenhouse or garden center at a home improvement store.
Layer the landscape rocks at the bottom of your vessel of choice, evenly covering the base and filling it about 2-3 inches high.
For the second layer, sprinkle horticultural charcoal on top of the rocks. This will be a thinner layer than the first, allowing the tops of the rocks to show through. The charcoal assists in draining, absorbs excess moisture, conditions the soil and adds nutrients for plant roots. Plus, it serves as a natural filter to deter odor-causing bacteria.
For the third layer, start by filling with potting soil about half way up the vessel. From there, determine if more soil is needed based on the size of your plant. A larger plant will need a larger amount to establish its root system.
Gently shake the excess soil off when transferring your plant from one vessel to the other, being careful not damage its roots. Place the plant directly into the new vessel.
Begin to fill the empty areas around the roots of the plant with more soil, pressing down to make sure the plant is set firmly in the soil, and is not loose or flimsy. Ensure all roots are covered by soil and none are exposed before moving on to the next step.
Now your plant is ready to be watered—and even though the plant now has proper drainage, you still want to be sure not to overwater it. When buying a new plant, ask a local greenhouse or garden center for proper care instructions.
For larger plants, repeat this same process, but add a larger amount of material per layer to tailor to the specific vessel you choose.
Our team had fun potting a few of these other plants—here is a short list of some of our favorites:
If you have any more specific questions about this method, leave a comment below. Don’t forget to tag us on Instagram to show us what you’ve come up with—happy planting!
This is a common piece of gardening advice, but it's true only for pots that don't have holes. If you're placing a container plant inside a larger, hole-less container, putting coarse material in the bottom of the outer container helps keep the plant's roots out of excess water. But if you're planting directly in the larger container, having gravel in the bottom is only a partial help to ensuring your plant's roots don't rot.
But the key point to remember: gravel in the bottom of a pot with holes does absolutely no good in ensuring good drainage. That's because water naturally flows toward finer material, not away from it, so the large air spaces between the pieces of gravel don't "pull" the water into them. So, at most, the gravel or clay shards simply prevent bits of soil from exiting through the holes.
The best way to ensure good drainage is to use a good-quality potting soil. Never use garden soil, because it's too dense for potting.
Root Rot and Why Good Pot Drainage is So Important
What exactly is root rot? For a full answer, refer to the quote below from the University of Wisconsin’s Horticulture website. In short, it is a general term that describes any moisture born disease that can deteriorate a plant.
“Any disease where the pathogen (causal organism) causes the deterioration of a plant’s root system. Most plants are susceptible to root rots, including both woody and herbaceous ornamentals. Root rots can be chronic diseases or, more commonly, are acute and can lead to the death of the plant.”
What is Root Rot?
Root rot is a disease that impacts the roots of plants and causes them to rot. Root rot is caused by poor drainage and overwatering. It is one of the biggest dangers to a plant’s health that can be caused by poor drainage.
According to the Wisconsin Horticulte Extension various types of soil fungi including but not limited to Pythium specialis, Phytophthora specialis, Rhizoctonia solani, and Fusarium specialis are capable of causing root rot in many types of plant, but root rot can be caused by any pathogen that causes root deterioration.
How to Tell if a Plant has Root Rot?
It isn’t always easy to tell if a plant has root rot because the symptoms are similar to those of a plant with a nutrient deficiency.
Signs of Root Rot
- Failure to thrive. If a plant is wilted or stunted and the gardener has been tending to it properly without seeing improvement, the culprit can be root rot.
- Nasty odor. A nasty smell coming from the soil of the potted plant could indicate root rot has set in.
- Rotten root. Roots afflicted with root rot will be brown and soft. They will appear to be rotten compared to the plump, firm roots of a healthy plant.
Is it possible to avoid having a problem with potted plants getting root rot? Luckily, it absolutely is possible. Below are ten simple tips gardeners can use to help their plants avoid the possibility of contracting root rot.
Ten Ways to Prevent Root Rot in Potted Plants
It is recommended that gardeners follow all of these suggestions to avoid the likelihood of a plant becoming contaminated with root rot. Prevention is always a better course of action than mitigation.
- Buy plants that come from a source of high reputation. Check all plants for root rot before making a purchase.
- Make sure proper care is being taken with repotting houseplants.
- Be sure to use a pot with drainage holes.
- Do not use drainage materials at the bottom of a pot.
- Use a commercial potting mix that is pasteurized over garden soil as garden soils can contain many of the root rot fungi.
- To further increase the planted pot’s drainage, add organic materials like well-rotted manure, peat moss or compost to the mixes of heavier pots. It is also important to note that these materials are often referred to as filler materials.
- Minimize contamination of the plants with root rot fungi by never reusing potting mix from an old houseplant’s pot or the water associated with it.
- After working on a potted plant that has root rot, be sure to disinfect any tools, work surfaces or clay pots or bowls used by cleaning them using either ten percent bleach, a detergent solution or alcohol. Most say that the reuse of plastic pots is not smart as these can be difficult to disinfect entirely.
- Most importantly, be sure to moderate the moisture the plant receives. Be mindful when watering plants and of how long the moisture can be visually observed in the soil of a potted plant. All plants need enough water to prevent stress from droughts, but excessively watering plants can be just as damaging as under-watering them.
- Relating to the last point, never allow a potted plant to sit in drainage water as root rot fungi can always grow in a brand-new wet environment.
By following these ten simple and common sense-based guidelines, a container gardener should be able to go many growing seasons without any root rot issues and enjoy healthy plants and bountiful harvests.
What to do if a Plant has Root Rot
Luckily when container gardening, root rot isn’t so bad. Imagine having a whole garden bed afflicted with root rot instead of just one potted plant.
However, most of the time if root rot has set in to the point that a gardener is noticing it, it is too late to save the plant.
If it is caught early enough, the plant may be able to be saved.
- Remove the plant from its pot and remove any of the damaged roots by trimming them off with clippers.
- Remove as much dirt as possible from the plant because that dirt is now contaminated with the pathogens causing the rot.
- Repot the plant with fresh soil and do not overwater it.
- Throw away or thoroughly clean the old pot, clean all tools used on the plant, and keep the plant in an area that is far away from the other plants in the garden.
Unfortunately, there isn’t much else that a gardener can do at this point with a potted plant contaminated with root rot. Some plants survive it, but many do not.
How to Improve Drainage in Potted Plants [5 UPDATED Strategies for 2020]
1. If you’re using the soil add plenty of compost
If you’re experiencing excessive drainage, it means that you need frequent watering. Otherwise, the water is lost too quickly and your plants might wilt and die.
The root cause for this problem could be that your soil has a high proportion of sandy soil. Universally, sandy soils are large textured and have poor water holding capacity.
On the other hand if your soil has too much clay, drainage will be hindered causing stagnation.
When this happens, the roots of your container plants will lack oxygen and suffocate.
Add compost to your soil and mix properly before planting.
You can buy ready-made, organic compost to get a jump start. But it’s easy and inexpensive to make your own with the right materials and good equipment.
Tumbling composter can help you to efficiently convert your kitchen and yard waste into rich soil enhancing compost.
Plus, time or money invested in your garden’s soil always brings the best returns: healthy, vigorous plants and great harvests.
And when you keep yard waste and kitchen scraps from the landfill you’re doubly rewarded.
Adding compost to your soil is like killing two birds with one stone since compost will solve the two extreme problems.
The organic matter in the compost acts as a sponge, holding water in the soil where the plants can reach it.
For the clay soils it opens up the porous structure allowing water to drain through.
2. Improve the texture of the soil
One of the easiest and fastest ways to improve the texture of your soil is by adding a course material such as sand or gravel.
Fine textured soil contains very small particles packed close together. This means that the pore space is reduced.
Now these pore spaces are reduced dramatically once they get into contact with water, replacing any existing air.
In turn, this causes massive water-logging.
To solve, this problem it is important to mix this type of soil with an opposite textured soil preferably sand, coco coir, and even compost.
You can either mix these materials together or arrange them in layers within your pot.
Some gardeners go to an extent of using rocks in their pots.
Rocks for drainage in pots
Adding a layer of rocks can be done to a non-draining pot as well as one with holes.
The idea behind this technique is that the rocks will act as a reservoir, storing excess water until the plant draws it up from the roots.
While for a pot with holes, they permit the excess water to flow away at the same time preventing the dirt from escaping.
You can use several types of rocks for this purpose.
Most gardeners use gravel made of granite or pebbles. In fact, this is the most popular tactic used by gardeners to improve the drainage of their potted plants.
However, being popular doesn’t mean it’s effective. This explains why very few of them succeed in container gardening.
Gravel or rocks at the bottom of the container doesn’t necessarily help.
To be precise, it’s ineffective.
There’s a phenomenon in container gardening called the Perched Water Table.
And I’ll discuss about it next.
This is a water saturation zone that could potentially deny the roots enough oxygen. Adding gravel elevates this zone causing problems to your plants.
The Concept of perched water table in pots
As I’ve mentioned earlier, in gardening, especially container gardening, you will often run into a phenomenon called a 'Perched Water Table' (PWT).
So what is PWT and how does it form?
This is a common scientific phenomenon known to scientist. But it is a foreign subject to most gardeners despite the fact that it affects them every day.
I’m going to explain this concept in the context of container gardening.
When watering your container plants, you might notice some sogginess at the bottom of the pot.
This water that doesn’t drain as intended is what we call PWT.
How does PWT then form?
The image below illustrates the formation process of a perched water table in pots.
Don’t mind my mediocre drawing because I’ll explain exactly what’s happening.
I’ll get a bit scientific but will try to explain as simply as possible.
First, let’s start with the basics:
Your favorite potting mix or growing media holds water by means of two natural forces.
These two forces are generally referred to as Matric Potential (MP) or generally explained as water potential. Simply put
Adhesion + Cohesion = Matric Potential (MP)
MP is responsible for retaining water within the pot so that the moisture is available to the roots.
You should also note that MP is always uniform within the entire container.
However, when you water your plants, there’s another opposing force in conjuction with capillary action that ensures, water penetrates into the media, moves through and across, and finally drains from the bottom of the pot.
We call this force – gravity.
It’s also the reason why the planet holds everything together – otherwise we would all be floating in the galaxy – I don’t know if that’s even possible.
Scientifically, it has been proven that gravitational potential (PG) is higher at the top of the container and lower at the bottom of the container.
From the illustration above, part A, which is also the upper zone, gravitational potential (GP) is higher than Matric Potential.
This means that irrigation water will flow seamlessly down the container without much resistant. Hence, the upper zone (A) is always the most porous and well drained.
Point B is the area of equilibrium, where GP is equivalent to MP. At this point the water slows the movement down the pot considerably.
The last part (C) is the saturation zone. There’s also another name for this zone. And yes, you guessed right.
It’s called the perched water table (PWT).
Formed as a result of higher matric potential than the gravitational potential.
Your key takeaway should be, PWT is a matter of physics and occurs in all containers and cannot be eliminated. What you can do is minimize its negative effects.
If you think about it, PWT isn’t necessarily a bad thing:
As long as the upper zone has the required air spaces to allow for healthy root growth, you could simply consider PWT or the saturation zone as a "reserve" of moisture for the plant roots.
The container size and height also play a role in the "location" of the Saturation Zone.
Taller, narrow containers will increase the upper zone while shorter, wide container will decrease the upper zone, the relative height / depth changes but the saturation zone actually remains the same.
Since the PWT remains constant regardless of the size or height of the container, it’s important to choose your container wisely.
3. Choose the right container or planter
When choosing a planter or container to host your indoor plants, consider the following aspects
A shallow container will affect the porosity of your soil or mix.
While a deep container with identical amount of mix will increase porosity thereby giving a boost to the pot drainage.
There are three main container materials.
These are self-watering, porous and non-porous.
Self-watering serves as a wick that transfers water to the potting media making it wet as required by the plant.
On the other hand the porous one allows water to escape through evaporation while the non-porous does the opposite.
If you choose a porous container material, be prepared to water your plants more frequently.
The rule of the thumb is to choose a planter that is proportional to the size of the plant. But it’s better to err on the higher side.
Smaller containers require frequent watering since they drain much faster.
Pot Planter's Drainage System and Your Choice
To start off this subject, I’ll let you in on a secret that you’re unlikely to hear it from anywhere else.
And that is at some point in your container gardening endeavor, after several months or years of sweat and tears, you’ll have to dig up those beautiful plants!
I have been there and done that.
But even more than my experience, is the fact that regardless of the plant you have or choose, the planter will clog reducing the drainage efficiency.
The only question is ‘when’ will that be and not ‘if.’
For some gardeners, it might be immediately thereafter, three months, six months, one year or ten years.
This time depends on the quality of your planter, and the thought process that went into the planter’s drainage system.
So if you have plans for specimen plants, or are planting trees that will grow too large for workers to lift by hand, make sure you have crane access to lift the trees, or some way to get fork lifts or other types of equipment like tripods in to lift the plants out of the planter for repairs, or to bring in new ones should major plants die.
I’ve exaggerated a bit may be and some planters can be repaired without moving the plants.
But let’s just say it is extremely hectic.
It’s also worth noting that planter drainage is often the weakest link in the delicate balance of nature required to maintain planters and container gardens.
If you’re like most people, you don’t want to go this route.
Instead, you’d rather choose a planter that can be durable enough at the same time, accommodate a sustainable drainage system that won’t clog the following day.
Consider these simple tips
I. If possible, keep the planter pots small
This facilitates easy re-potted plantings that you can lift out, in pots which slope evenly outward as the pot wall moves towards the top. This simple classic form facilitates the removal of the plant to clean out blocked drainage holes without damaging either the pot or the plant.
II. For large planters use a saurcer
Consider a system at the bottom that can help you pump out excess water, especially after a heavy down pour for outdoor pot plants.
III. Use corrugated piping also known as tiling
Where proper drainage cannot be achieved through natural means, corrugated piping called tiling may be installed below the growing surface to move moisture away from the plant's roots.
4. Instead of the soil, use potting mix
You can save yourself the trouble associated with soil-based media by using recommended potting mix.
Most mixes have good porosity.
And as we already know, porosity is one of the most important properties of a potting mix.
It is the space available within a mix for water, air or root growth.
Small pores contribute to water retention whereas large pores promote aeration.
You can buy a ready-made organic potting mix or if you’re a do-it-yourself freak like me, you can make your own.
Regardless of your option, it’s extremely important to understand the general characteristics of a good pot mix.
To kick you off, I’ll list some of those characteristics so that you can make an informed decision should you choose to buy. It’s even more important if you want to make your own.
Characteristics of a good potting mix
- Drains well, which means an air-filled porosity of at least 15%
- Easy to re-wet – some peat and bark media are difficult to re-wet if they dry out
- Stable – meaning that it does not shrink away from the side of the pot as it dries
- Reasonable weight – not too heavy to lift, not so light as to blow over easily
- Optimum pH, between 5.0 and 6.5 is satisfactory for most plants (all pH values quoted are measured in water)
- Pest and disease-free, for example weed seeds, fungal pathogens, or can be sterilized without producing harmful by-products
- Easy to store - can be stored for short periods without significant changes in physical or chemical properties
- Cheap and readily available.
Finally for my fellow DIY freaks, understanding these properties is good but they won’t results to anything substantial until you get your hands dirty.
Luckily I’m here to tell you exactly what to do.
However, I won’t go in to much detail because there are better resources out there on this subject.
But first, let’s take a look at the popular mix components.
These are peat, coconut coir, vermiculite, pine bark, perlite, sand, zeolite, soil, animal manure, wood chips, and sawdust.
The perfect soilless potting mix recipe
Soilless mixes do not contain any soil – as the name suggests, but generally consist of peat moss combined with horticultural grades of vermiculite and/ or perlite and thereafter adding a fertilizer.
Peat-based media are useful for seed germination because they are relatively sterile, light in texture and weight, and uniform.
The light texture enables seeds to readily germinate and emerge, allowing tender roots to grow, and makes transplanting seedlings easier later on.
In general, standard media recipes are created based on the types of plants being grown (ex. bedding plants, potted plants, or for seed germination).
For general plants, you can use the following mix ratios:
Sawdust: pinebark: peat: sand
A standard recipe for a homemade soilless mix consists of half sphagnum peat moss and half perlite or vermiculite.
To mix ½ bushel basket or four gallons of media:
1. Start by pouring two gallons of peat moss into the bushel basket.
2. Add two gallons of either perlite or vermiculite and mix thoroughly.
3. Moisten the mix before using in pots or flats.
4. Add limestone to condition the mix
5. Add a fertilizer as required
Case Study: Fred’s soilless mix success story.
A few years ago, Fred was having a heated debate with his uncle over some aspects of container gardening.
His uncle always liked to win arguments and this occasion was not exceptional.
At the time, the uncle was a to-go-to person about all things gardening.
But he had one problem he believed in his own righteousness regardless of the facts presented.
For instance, he held a view that soil alone was enough to sustain pot plants.
When Fred pointed out the issues of soil compaction and subsequent reduction in porosity, his uncle wanted to hear none of it.
Fred was rudely interjected by a now visibly furious uncle, “you don’t know what you're talking about. I have been growing plants a lot longer than you and therefore I have more experience.”
And that was the end of their conversion for that day.
Fast-forward and Fred was having a family gathering at his home the other day.
He decided to brag about his new green friends growing in containers.
When he showed his family members all the plants he had, from citrus, to gardenias, to strange and exotic plants from Africa, to the deep Orient, gardenias, cucumbers, and many others, growing as happy as they could be, they all got jealous!
And for that they asked lots of questions.
They wanted to know what in the world he was doing different! Fred picked each plant up and showed them the soil-less mix they were all planted in.
Some were neatly planted in the 5.1.1 mix and some in the 1.1.1 gritty mix.
Fred’s family members couldn’t believe he even knew of the stuff. He went ahead showing them even the fertilizers he used.
Funny enough, his uncle was there too.
Yes, the very same man that couldn't keep much of anything alive in containers except seasonal stuff and kept bragging of years of experience, now was convinced that his nephew had something there.
Every year most of the family members had to buy a new gardenia, because by the time spring approached, the peat mix they use seemed to suffocate the roots by the following summer, not to mention the mites and the knats they had to fight all winter in their bed room
But now thanks to Fred with his discovery, they had finally found a solution.
Today they commend him and say in all their years, they never thought Fred could grow such beauties through their cold long lack of sunlight winters.
By simply doing minor tweaks, Fred was able to succeed where others were failing. He was successful because he paid attention to the well-being of his plant roots and so can you.
If you want to succeed in container gardening, take care of the soil rather than the plant.
If you want to succeed in container gardening, take care of the soil rather than the plant. #containergardening