Bottom watering is a technique that has been present for decades and has served many gardeners well. However, as it has slowly gained traction, many people find themselves with problems regarding just how to do it properly. Of these problems, one of the most common ones is getting water to reach the top of the soil while watering.
Water is not reaching the top while bottom watering because you need more water in the tray. Although bottom watering moves water into the pot, it’s still important to have enough water in the tray initially. Problems such as rocks in your pot and poor soil absorbance can also play a part.
Not having enough water is the most common reason for water not reaching the top, but it is not the only one. There are quite a few others, and this article will go into much more detail on them, so sit back and read on if you’d like to learn more about how to correctly bottom water your plants!
4 Reasons Why Water is Not Reaching the Top While Bottom Watering
Of all the reasons water might not be reaching the top of the soil while bottom watering, the amount of water you’re using is the most common. However, it is far from the only reason.
Here are the most common reasons why water is not reaching the top of the soil while bottom watering:
- You need more water.
- You’re not soaking your plant for long enough.
- Your soil is too rocky or compacted.
- There are no holes in the bottom of the pot.
You Need More Water
Of course, the primary reason for water not reaching the top is insufficient water. Intuitively, it might seem like the amount of water you use in your tray should not be that important since the water moves from bottom to top anyway.
However, that is far from true. To properly understand how bottom watering works, it’s essential to take a detour now and explain its science.
When you water your plants from the bottom up, the liquid moves from the tray outside the pot to its insides by absorption and capillary movement.
Absorption happens when cells (in this case, soil) take in water or another liquid. As these cells pull in the water, the soil cell swells until they can’t take in more fluids. This ‘fullness’ is called saturation.
Once the cells at the bottom of your pot reach capacity, there is no more room for the water, and it must move on to the neighboring cells.
This movement carries on until all of the cells are full, and hopefully, the entirety of your soil is wet. However, when there isn’t enough water, the neighboring soil cells won’t be able to reach the puddle in your watering tray. In such cases, your pot will have a soggy bottom and dry top.
With a more precise picture painted, it’s easier to understand why not having enough water is the core reason water will not reach the top of your soil. Most of the other reasons deal with obstructions and limitations to water movement, but you must have enough water before anything else!
The good thing is that this problem is straightforward to solve. Simply add more water to the tray. The main worry that stops people from doing this is the fear of overwatering their plants with this technique.
While this is a problem with things like root rot, it’s still important to understand that bottom watering comes with the added benefit of essentially giving your plant and its soil the choice of taking only the amount of water they need.
Since water moves upwards without needing outside interference, it will also usually stop on its own when it reaches an equilibrium. Provided you drain the soil properly afterward, you should have nothing to worry about.
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 allow for this if you want water to reach the top of the soil.
A good rule of thumb is to leave the water in the watering tray for 30 minutes to an hour. This time usually gives enough of an allowance for water to permeate the soil thoroughly.
Alternatively, if leaving your water in for such a long stretch worries you because of root rot or damp soil, then it might be a better idea to water in short time frames. This method simply means you leave less water in the tray for less time and top it up when that period is over, provided the top of the soil is not yet wet.
Your Soil Is Too Rocky or Compacted
If you have the time and water level right, the next most likely problem is obstructions in the soil. These obstructions are usually rocks or compacted soil.
Rocks on their own are not harmful to plants, and many people use them to provide a better anchor for plant roots. However, stones can become a problem if you have too many of them in the soil, especially if they’re large.
Since water moves upwards through spaces in the soil (capillary motion), it needs some space to maintain its upward momentum towards the top. However, too much space also means that the water will not be able to move through the container from one soil particle to the other (absorption).
The other side of this coin is that in the absence of rocks, tightly packed earth with no spaces can cause enough obstruction that the water will not be able to get through. With no space, capillary motion cannot happen, and the water stays close to the bottom of the soil.
The soil does not always have to be tightly packed to cause a problematic obstruction. Using the wrong potting mix can also cause similar problems to tightly packing it. The most common example of this is clay.
If you have a high percentage of clay in the potting mix, it can be difficult for water to get to the top. Clay has a high moisture capacity, so it absorbs so much water that none of the moisture will be able to make its way to the top of your pot. At the same time, it also has narrow spaces, which are usually suitable for capillarity.
However, clay can constrict over time, and the narrow spaces can close up as the clay solidifies, especially during hot weather. Although the entirety of the potting mix might not turn rock-solid, it can clump up enough to stop water from moving upwards.
So, essentially, clay is not a suitable soil type for bottom-watering.
There Are No Holes at the Bottom of the Pot
The final, most common 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.
Alternatively, you could make the incisions yourself, but depending on what your planter is made of, you could just as easily cause a crack instead of a hole.
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, some people say it’s necessary, and some say it isn’t.
Water does not need to reach the top while bottom watering as your plant might have enough water, even if the topsoil is not wet. Since plant roots are not at the top of the planter, water does not need to reach there.
However, soaking your plant until the water reaches the top is the best way to ensure that the roots have received enough moisture. If you do not want water reaching the top, however, the best thing to do is to intermittently measure the amount of water.
While the best way to do this is to calculate wet and dry weights as the water moves up in the soil, the downside is that this method is highly cumbersome and, honestly, mostly unnecessary.
The best way to go about it is to use the finger method to test. This method involves sticking your forefinger into the soil to the second knuckle to check its moisture. If the soil is moist at the tip of your finger, then you can stop watering.
Conclusion
Bottom watering is a great way to evenly water your soil and reduce the probability of overwatering and underwatering. However, if water is not reaching the top, the most likely problem is needing more water in your watering tray.
Regardless, if you plan to bottom water your plants for a long time, you need to remember to leach it frequently by top watering to reduce nutrient accumulation.
