You must have heard the age-old tip passed down from generations – put rocks and gravel at the bottom of a planter pot for better soil drainage. But is it really sensible advice? Should you put rocks in the bottom of a planter pot, and does it actually aid in drainage?
The answer will depend upon your pot’s size, the presence of drainage holes, and the kind of soil you use. Let’s find out…
Should You Put Rocks in the Bottom of a Planter Pot?
Yes and no – they stop the plant from falling over, allow for drainage, and can add to the aesthetic appeal of your plant. However, adding rocks to a plant pot isn’t a strict requirement. Generally, you wouldn’t need to use a rock, gravel, and pebble layer at the bottom of a pot with drainage holes, especially if you have a good pot.
A good pot and all good pots come with drainage holes or holes. Here are the top benefits of using rocks in the bottom of a plant pot:
To Avoid The Plant From Toppling Over
When you have a plant that you want to be situated at one spot, adding rocks will help keep it in place. If the pot you are using is very narrow, you might want to use rocks at the bottom. Filling a layer of rocks makes the pot heavier and prevents it from toppling over. In such cases, you can happily use rocks and gravel at the bottom of your pot.
For Pots Without Drainage Holes
Another reason to use rocks would be when you have a pot without any drainage hole. In such case, you would need a layer beneath the soil where the water can sit. This is so that your soil isn’t too saturated, but be careful, as you can unknowingly be overwatering your plant.
The layer of gravel or small rocks can help the water be reabsorbed by the plant and catch excess water. But water doesn’t travel well from one medium to another in the case of soil and rocks.
Most soils can drain pretty well on their own, so your rocks may not be all that helpful.
Garden Myths About Pot Rocks
These garden myths have led many to believe that rocks at the bottom of a pot are essential. The reality is far from the truth. You might think that it has previously worked for you, and why not keep doing what everyone once swore by? That is why it is important to understand how rocks actually function at the bottom and if your soil needs it.
Drainage Using Rock Layer At The Bottom Of The Pot
The rocks at the bottom of your pot don’t help with drainage as much as you may have thought. As mentioned earlier, the only times rocks could help is when your pot is devoid of any drainage holes.
In pots with drainage holes, the water isn’t drained faster with the help of those rocks. Instead, you might get a Perched Water Table.
What Is Perched Water Table?
The Perched Water Table or PWT phenomena is when the saturated zone of the soil doesn’t drain the water to the rocks. Instead, it gets closer to the roots and is harmful as it can cause root rot.
A famous example would be that of a sponge. Even after you lay a saturated one on gravel, you won’t really see any water traveling from the sponge to the rock.
The water doesn’t shift mediums so quickly and instead holds on to the sponge (or soil), and no drainage occurs. So the moisture in your soil will be “perching” at the bottom instead of draining away using the rocks.
Do Plant Pot Rocks Improve Air Circulation?
Another myth associated with a rock layer at the bottom of plant pots is that it would allow for better air circulation. Logically, it’s not really possible. The air won’t travel from the bottom and upwards.
The soil will already be filled with moisture and air, and no rocks will help the air circulate. Certainly not from the bottom.
How To Prevent The Soil From Washing Away?
If putting rocks at the bottom isn’t a good solution, then you might wonder what you should do to prevent the soil from washing away. Sure, you don’t need to put a heap of them, but one rock to cover your hole should be enough.
Alternatively, you could also use a coffee filter, newspaper, or light fabric to prevent the washing away of soil. Since they’re porous materials, they’ll be able to drain away from the water easily.
If Not Rocks, Then What To Use To Drain The Water?
Now that you know that a layer of gravel and rocks won’t be equipping your soil with water drainage superpowers, you will want to know what to use instead. What you need to pay the most attention to with regards to water drainage is the potting mix.
The kind of soil and the mix you use will hugely determine the type of drainage your pot will see. If your plant is succulent or requires high water drainage amounts, you should carefully choose potting mixes with fast drainage. These should include materials that are highly water absorbent. Often perlite, dry barks, coarse sand, etc., are widely used for speedier drainage and drying.
Use the 1:1 ratio of potting mix with sand for succulents and a 1:1:1 perlite, potting mix, and dry barks for other plants. You can make your own ratios of potting mixes but make sure what you use is suitable for your plant’s drainage requirements.
It’s better to go with a suitable potting mix and avoid garden soil. Often it is filled with contaminants and debris that is not productive for plant health.
What To Do If The Pot Already Has Rocks At The Bottom?
Generally, if it’s not very useful, the rocks aren’t extremely harmful to plants in cases of bog pots. If your pot is small and cozy around your plant, and if the fit is snug, then you might want to repot. If there is not much room for roots to grow around, then the perched water table might cause root rot.
Unless you think there is enough space for your plant in the pot and the pot is bigger, then you can forego repotting. Be careful if you decide to repot as it’s not always suitable for your plant, especially if they are sensitive ones.
So, I hope this article helped you to come to an answer about whether or not to put rocks at the bottom of a plant pot. To confirm, rocks are only needed if your pot has no drainage holes. Furthermore, they don’t provide amazing drainage, and can even cause root rot. Better alternatives are porous materials like coffee filters, fabrics, and paper.