The last thing we want to do when planting out flowers, vegetables and young plants is to prejudice their development in any way. It takes such a lot of care and attention to get things right that we’d kick ourselves if easily-avoided issues like overwatering caused our plants harm. That’s why we need to be careful with the drainage in our planters.
All planters, whether wood, ceramic or plastic, should have drainage holes so the soil remains well drained. This means plant roots can get enough air and don’t get waterlogged. Drainage holes are also needed to stop mineral build up in the planter, which could also harm plants.
In this blog post we’re going to look at whether different types of planters should have holes, how to make them if they don’t have them – and consider any alternatives for improving drainage in planters. We’ll also assess if lining planters is a good idea or not.
Do All Planters Need Drainage Holes? (Is Drainage Important?)
The short answer is yes, all planters should have drainage holes. There are a few important reasons for this.
Drainage holes allow excess water to drain out of the pot. Even plants that thrive in damp conditions don’t like having waterlogged roots.
Soil that’s heavy with water doesn’t have good airflow, which is similarly bad for the roots. Well-drained soil is full of little pockets of air, and waterlogged soil plugs these essential gaps. A plant that’s kept in wet, airless conditions will develop root rot.
Then there’s mineral build-up. Unwanted salts normally drain away with the water. Salts from fertilizers can gather in the soil, and with no chance to pass through, could build up into unhealthy quantities.
This seems a little odd; however if we have a planter without holes, we’re more likely to dry out a plant. This is because if we’re aware that drainage is poor, we naturally give the plant less water to compensate for this.
Should Wooden Planters Have Drainage Holes?
A wooden planter needs to have drainage holes for the reasons we outlined above. Excess water needs to pass through the container, and the roots need plenty of air circulation.
The only possible exception is if you’re using a stylish wooden planter as a decorative outer layer for a plastic pot. For example, you might want to keep your plant in its plastic pot (most of which come with ready-drilled holes) and stand it in a wooden trough. Even in this case, you might still want holes in the wooden planter as well, to prevent the timber base from becoming waterlogged.
What if your wooden planter doesn’t already have holes? Well, wooden containers are the easiest ones to drill holes into (and we’ll look at how you do this in a moment).
Should Plastic Planters Have Holes?
Plastic planters need holes, too, and those plastic pots our plants normally come in always have generous drainage.
When it’s time to move our new plants to their new home, many of us decide to stay with plastic pots as they’re robust and long-lasting. They also come in lots of attractive designs without costing too much to buy. However, occasionally we’ll get our new plastic pot home and discover it doesn’t have any drainage.
If you take a closer look at the base, it’s very likely that a hole-free plastic planter will have several small indentations in the plastic. These are like pre-punched holes that can be removed with just the touch of a drill.
So why not simply have holes in the first place? This is to give gardeners a choice as to how they use their new pot: is the soil and plant going directly into it, or is it going to be the decorative “sleeve” for another pot?
How Many Drainage Holes Does a Planter Need?
We reckon if you went from yard to yard in your block, and asked each gardener how many holes should a planter have, you’d get a different reply from each one! So, we reckon there isn’t a strict rule on this, but three or four seems to be a reasonable amount.
Some planters come with just a single central hole, which may be OK in a small pot but isn’t OK for larger containers. This is because the holes create escape routes for the excess water. If there’s only one escape channel, there’s still the risk of waterlogging.
The main issue is size not number. If the hole is too big, the soil will simply leak out along with the water. Too small, and the holes may get clogged and cease to drain. Again, there isn’t really consensus on this, but around four holes of about a quarter of an inch in diameter seems a sensible approach.
How To Drill Holes in Your Wood, Ceramic or Plastic Planters
You should be able to drill your own drainage holes provided you have the right tools. Most types of pot can be drilled without damage; however, if it’s a precious pot, we’d advise trying another approach (and we’ll look at some ideas for drainage-less pots in a minute).
You’ll need an electric drill plus the right drill bits, old newspaper or a sheet, a nail, a permanent marker and some masking tape. You may also want to wear safety goggles. Pop the newspaper or sheet on the ground to catch the dust and turn the pot upside down. Here goes…
These are easy to drill into, and a normal drill bit should suffice. Mark where you want the holes to go with the pen, then using the nail, make a small indentation for the drill to grip onto to prevent slipping. Holding the drill in an upright position, slowly drill downwards until the hole is made.
Slightly more tricky, as you’ll need to make sure you have a masonry bit for your drill. If the pit is glazed, you’ll need a tile or glass drill bit. When you’re drilling into the base of a ceramic pot, put masking tape over the area that’s going to be drilled, which will help to stop the drill from slipping. Otherwise, carry on as with the wooden planter: mark the holes and drill slowly downwards.
If these have those handy little indentations, your job is half done. Using a standard drill bit, simply drill gently into these almost-holes. If there aren’t any, follow the same process as for a wooden planter.
How Do You Use a Planter Without Drainage Holes?
If your planter doesn’t have holes and you don’t want to make any, what should you do? One solution is to create a better drainage system inside the pot. Some people advocate adding activated charcoal which naturally absorbs water. It’s also antimicrobial, which can help to keep your plant healthy.
Most plants need a drainage layer at the bottom of the planter, whether it has holes or not. This is typically made up from old, smashed ceramic pots or pebbles. Ensuring that you have a good drainage area, which creates air pockets and can gather up excess water, may be of some help in preventing waterlogged soil.
However, nothing beats the natural drainage you get from those few simple little holes. If you want to use a planter without drainage holes, we’d suggest using it as an outer container, and “double potting” the plant. Just keep an eye on the space between the two pots, and make sure this doesn’t fill with water (keeping the plant out of the rain will help, so you can monitor how much water it gets).
Should Planters Be Lined With Plastic?
Lining a pot with plastic has some benefits. If your planter is made from a porous material like clay, it can soak in the moisture from the soil. Wooden planters can do the same, and can also start to deteriorate after a time if they’re not treated in some way.
You can simply pop a cut-off piece of plastic liner inside your pot, and let the stones, soil and compost weigh it down. But – you must make sure that it has drainage holes in exactly the right places, and that it doesn’t slip out of place. For that reason, this can sometimes be a risky measure. You can buy ready-shaped liners that may be a more stable fit.
Coir, moss and galvanised metal wire can also be used, depending on the type of pot and plant. The easiest way is to use a simple plastic pot, the type that plants come in from the garden center, and stand this inside your chosen container. If they both have holes, so much the better.
Ultimately, all planters need drainage holes so your plants don’t get waterlogged roots, have enough air flow and don’t get killed by the build up of harmful minerals.
So whether your planters and pots are made of plastic, wood or ceramic – if they don’t have drainage holes already then you’ll need to make some using the method described above.For a single sized planter you’ll need one hole measuring a quarter of an inch in diameter, while for a standard rectangular planter you’ll need four holes of the same size.
Now, where did I put that drill? 🙂
Homeowner and property investor Larry James founded Take a Yard in 2020 to bring you the very best outdoor living content, based on his years of experience managing outside spaces. Read more >