Bottom watering is not a new gardening technique. But it has recently exploded in popularity among the houseplant community online thanks to several viral videos explaining its benefits. If you’ve tried this technique yourself, you may have noticed a common problem gardeners often have – the top layer of soil remains dry.
The most common reasons why water does not reach the top while bottom watering include:
- You need more water.
- You’re not soaking your plant for long enough.
- Your soil is too rocky or compacted.
- There are no holes at the bottom of the pot.
Once you can identify the reason why the water is not reaching the top when bottom watering, these quick fixes will ensure the soil is completely saturated each time you water.
4 Reasons Why Water Is Not Reaching the Top While Bottom Watering
There are many reasons why water might not be reaching the top of the soil while bottom watering.
These are some of the most common to look out for:
1. You Need More Water
The primary reason for water not reaching the top is simply that there isn’t enough water for the soil to absorb.
Gardeners often don’t consider the amount of water they use when bottom watering. I made the same mistake when I first started gardening, simply filling the bottom of a tray or container until the base of the pot was covered and hoping for the best. But the amount of water you use has a direct impact on soil saturation, especially for larger pots that hold large amounts of soil.
When you water your plants from the bottom up, the liquid moves from the tray and to the soil through absorption and capillary movement. Once the soil at the base is saturated, moisture continues to move upwards to dry spots until the soil is completely saturated or you run out of water – whichever comes first.
Most of the other reasons deal with obstructions and limitations to water movement, but you must have enough water before anything else for bottom watering to be successful.
Luckily, this problem is easy to solve. Simply add more water to the tray until all the soil is visibly saturated.
The amount will depend on how dry the soil is initially and how large the pot is. For large containers, it’s easier to use a bucket or even your sink to hold more water rather than a shallow tray that will dry up quickly.
The main worry that stops people from doing this is the fear of overwatering and subsequent root rot. However, the soil will never absorb more water than it is able to.
In other words, once it is saturated, it can’t become ‘more’ saturated. Any extra water the pot is sitting in will drain once you lift it out of the tray.
As long as you don’t leave the pot sitting in water for long periods and drain any excess from the holes at the bottom of the container after bottom watering, overwatering is highly unlikely.
2. You’re Not Soaking Your Plant for Long Enough
All the water in the world won’t help if you’re not leaving the pot in water for long enough. Regardless of how much water you have in the tray, capillary action takes time, and you need to wait a while if you want water to reach the top of the soil.
As an impatient gardener, this is one step I struggle with. After 15 minutes, I’m keen to put the plants back and finish the process. But this isn’t nearly enough time for all the soil to soak up the moisture it needs, leaving the top layer (and potentially more) without moisture.
A good rule of thumb is to leave the water in the watering tray for 10-30 minutes. This is usually enough time for water to permeate the soil thoroughly.
You can adjust the time depending on the size of your container. The more soil there is, the longer it will take to become fully saturated.
It’s important not to go to the other extreme and forget the plant in the water either. As soon as you notice the top layer of soil is moist, remove the plants and drain the excess to limit any chances of fungal growth or root rot.
3. Your Soil Is Too Rocky or Compacted
If you have the time and water level right, the next problem to look out for is obstructions in the soil. Rocks are one culprit, but severely compacted soil that has become hydrophobic is another potential cause.
Rocks on their own are not harmful to plants, and many people use them to improve drainage, aeration, and better match the soil conditions the plants are used to in their native habitats. However, stones can become a problem when bottom watering, especially if they are large.
Water moves upwards through the soil from particle to particle. However, if there is too much space between particles due to large rocks that limit upward movement, the water will struggle to reach the top layer of soil.
On the other hand, tightly packed soil with no gaps at all can cause enough obstruction that the water will not be able to get through. Capillary action cannot happen, leaving the soil dry and the moisture close to the bottom of the soil.
Incorrect soil type is the most common reason for this issue. If you have a high percentage of clay in the potting mix that is clumped together, it can be difficult for water to get to the top. Old and disintegrated soil or soil that is pressed too tightly into the container can have the same effect.
In these cases, it’s best to repot your plant into an improved soil mix or choose a different watering technique.
4. There Are No Holes at the Bottom of the Pot
The final error that many people run into when bottom watering is not using the proper pots. Not all containers are suitable for bottom watering, and if you’d like to start bottom watering your plants, you’ll need a pot with holes in the bottom.
Drainage holes allow water to enter the soil directly without soaking the pot itself. So, if you want to get water to your plant’s roots, be sure that you get a pot with an exposed hole at the bottom.
All containers should have drainage holes anyway to prevent rot, so if yours doesn’t, it’s best to choose a new container or make holes in the existing container yourself.
Does Water Need to Reach the Top While Bottom Watering?
For most people bottom watering their plants, getting water to the top is usually the clearest indicator that the watering session is over.
However, water does not need actually need to reach the top while bottom watering. Since plant roots grow downwards into the soil and not up into the top layer, the moisture only needs to reach the lower parts of the soil where the roots are for the plant to grow successfully.
Soaking your plant until the water reaches the top is the best visual way to ensure that the roots have received enough moisture. But you can also test the soil with your finger to determine how much of the soil is saturated.
This method involves sticking your forefinger into the soil to the first knuckle. If the soil is moist at the tip of your finger, you can remove the pot from the tray. Allow the excess water to drain before placing your plant back in its home.
The Verdict
Bottom watering is a great way to evenly water your soil and reduce the probability of underwatering. If water is not reaching the top, the most likely problem is needing more water in your watering tray.
You can also use your finger to determine how far the moisture has traveled, giving you an indicator of when to remove the plant from the water without saturating the top layer.
Written by Alexander Picot, Reviewed by Madison Moulton
