Bottom watering is an effective watering method for container plants, completely saturating the soil and keeping your plants happy. However, despite the simplicity of the method, there are issues that prevent bottom watering from working correctly or within the typical time frame. If your plants are not thriving when you bottom water them, there are several reasons why this could occur.
Bottom watering may now work effectively due to factors such as soil quality, pots, water levels, and drainage holes. Larger planters can also take longer than usual to absorb enough water. And if the absorption rate is too slow, you can drill more holes in the bottom of the pot.
This article will explore why bottom watering your plants may not work and how to prevent complications when applying this method.
Factors That Affect Bottom Watering Efficiency
When bottom watering, plants need to be submerged in water for around 10 to 30 minutes on average for the soil to finish absorbing enough water to satisfy the roots.
Many plant owners use it as a primary way to water their plants because of its effectiveness and lower risk of underwatering. However, there are potential complications when using this method, depending on your plants and the container they are planted in.
1. Your Drainage Holes Are Insufficient
For bottom watering to work at all, there must be at least one drainage hole at the bottom of the pot. Pots without drainage holes are common in decorative cover pots, so don’t beat yourself up if you notice it lacks holes. Luckily, you can simply make holes at the bottom of the pot to allow for water absorption and drainage.
Some earthen planters, such as terracotta, are made without a drainage hole. Since it is a porous material, the soil can still absorb water. However, this will take much longer than the typical 10 to 30 minutes and isn’t as effective as drainage holes.
Check the moisture levels in the soil with these three easy steps:
- Push your finger into the soil close to the planter wall.
- Go as far down as your second knuckle.
- If you don’t feel moist soil, wait another 5 minutes and recheck it.
2. Not Enough Time to Hydrate the Root System
As mentioned, bottom watering can typically take between 10 and 30 minutes for the water to evenly hydrate the entire root system of your plants. However, that is not a ‘one size fits all’, because 30 minutes will not always be enough time for this method to work.
The time it takes for bottom watering to work effectively can be longer because:
- Dense soil absorbs water substantially slower than regular potting soil and will take longer to reach the roots.
- The size of your pot can contribute to longer absorption times.
- Along with the pot size, the dryness of the soil will also prevent bottom watering from working within the typical time.
- A potting mix rich in peat moss may become hydrophobic when allowed to dry out before watering, slowing down the water absorption rate.
It’s imperative to consider these factors when you check your soil after 30 minutes. If it’s still dry, it doesn’t mean it’s not working. It’ll just take longer.
3. Your Soil’s Absorption Rate Is Too Slow
Soil naturally wicks the water upwards towards the roots when using the bottom watering method. That’s why the composition of your soil can have a significant impact on how long effective bottom watering takes.
The absorption rate and success can depend on the following factors:
Added Materials
If you have large soil amendments such as bark chips, they may clog the drainage holes.
Soil Density
If the soil is too dense (like clay soils), the smaller particles and pores will slow the absorption rate. So, you’ll need to amend the soil with materials like coconut coir and perlite to improve conditions.
Soil Dryness
When your plant’s soil is bone dry, it will take longer for bottom watering to work. Setting it in water for 30 minutes just isn’t going to cut it.
Soil Amount
The larger the planter, the more soil it houses, and the opposite is true with small planters. Larger pots will take longer to absorb enough water to moisten all the soil. Smaller pots may only need 10 minutes to thoroughly wet the roots.
You’ll need to consider these factors and leave your plant in water until you poke your finger in the soil and feel moisture, which could take an hour or several hours, depending on your pot size and soil condition.
4. Your Water Levels Are Incorrect
When you fill the container or sink with water, there should be enough moisture for the soil to soak up without drying out. The capillary action of soil wicks the moisture upward against gravity to the root system, but can only do that when the soil level is above the bottom of the container.
Larger pots have more soil to absorb the water and will need a higher water level than your ‘average’ size pot and more time to complete the water uptake.
5. You Have a Bottom Rock Layer
Gardeners often suggest using rocks to layer the bottom of the planter to assist with drainage, especially in planters with no drainage holes. Not only will this cause bottom watering to be ineffective, but it will also cause health issues for your plants.
When the container lacks drainage holes, water accumulates at the bottom layer. Rather than draining away, the water stagnates, attracting harmful bacteria that can spread to the roots. It’s also hard to tell how much water you’ve applied, meaning the water may still be soaking into the soil without you realizing it.
Avoid using rocks at the bottom of any plant container if you want to be able to bottom water in the future.
6. Your Mineral Concentration Is Too High
About once a month or every few waterings, you should water your plants from the top. This top watering will prevent the salts and other minerals from becoming too concentrated.
When there are too many minerals in the soil, your roots will begin to show the following signs:
- The plant leaves appear droopy.
- The leaves are wilting or falling off.
- There is browning or yellowing of the leaves.
- The tips of the leaves appear ‘burnt.’
- There is a white powdery residue on the top of the soil.
Some of these signs can also show that your plants are not receiving enough water, making you think bottom watering isn’t working. And that is why checking the soil is frequently mentioned.
Poking through the top of the soil will confirm the soil is wicking the water to the roots and that you need to look for other potential causes for these worrying signs.
How to Prevent Complications
Having the correct potted environment for your plants will make them (and you) happy because there will be fewer complications during your care routine.
To prevent issues when using the bottom watering method, go through the checklist below:
- Ensure all of your pots have at least one hole to allow water absorption through the soil.
- If you need more holes for water absorption, you can add more holes by drilling (there are also non-drill methods if you’re using plastic pots).
- Plant in the correct soil mix.
- Use the proper amendments for your soil mixture.
- Make sure nothing is clogging the drainage holes.
- If you have stones layering at the bottom of the planter, remove them.
- Flush excess minerals by top watering once a month or every few waterings.
- Always push your finger through the top soil layer to check for moisture.
There aren’t many issues that can prevent bottom watering from working when you have the right soil conditions, amount of water, and drainage holes to allow the soil to wick the water to the roots to hydrate your plants.
Final Thoughts
The bottom watering method is highly effective in hydrating your plant’s root system uniformly. Some contributing factors can slow the process or prevent it from working.
Ensure you have checked the following:
- Check for drainage holes and make sure they aren’t clogged.
- Consider soil dryness, density, and added amendments contribute to longer absorption times.
- Have the correct soil media for your plants with a low ratio of dense soil, like clay.
- The water level should be higher than the bottom level of the soil.
- If you have rocks lining the bottom, remove and replace them with soil.
Written by Alexander Picot, Reviewed by Madison Moulton
