Bottom watering plants is an effective method without experiencing any issues. However, there are times when you may experience complications that prevent this method from working correctly or within the typical time. If your plants are not thriving when you bottom water them, there are several reasons why this could occur.
Bottom watering doesn’t work effectively due to factors such as your 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
Typically this method takes about 10 to 20 minutes for your plants to be submerged in water until the soil finishes absorbing enough to moisten the plants’ root system.
The bottom watering method is an excellent way to hydrate the root system of your plants evenly. Many plant owners prefer it as a primary way to water their plants because of its effectiveness and lower risk of overwatering. However, there are times you’ll experience complications while using this method.
1. Your Drainage Holes Are Insufficient
For this method to work at all, there must be at least one drainage hole on the bottom of the pot. Pots without drainage holes are common, so don’t beat yourself up if you notice it lacks holes. And it’s an easy fix because you can make holes on 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 may take longer than the typical 10 to 20 minutes, so check the soil often for dampness. Check 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. Allowing Enough Time To Hydrate the Root System
As mentioned, bottom watering can typically take up to 20 minutes for the water to uniformly hydrate the entire root system of your plants. However, that is not a ‘one size fits all’ because 20 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 of the following:
- 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.
It’s imperative to consider these factors when you check your soil after 20 minutes because if it’s still dry. It doesn’t mean it’s not working. It’ll just take longer.
3. Your Soil’s Absorption Rate Affects Bottom Watering
Soil naturally absorbs water and wicks the water towards the roots when using the bottom watering method. Since soil is the common culprit in this matter, you should check your soil and replace it if needed. The absorption rate and success can depend on the following factors:
- Added Materials: If you have added amendments such as wood chips, they may clog the drain holes.
- Soil Density: If the soil is too dense with clay, it creates difficulty when attempting to bottom water your plants. Because clay includes smaller particles and pores, the absorption rate of this type of soil is considerably less than your typical potting soil. So, you’ll need to add a higher ratio of a lighter soil mixture that absorbs water much better.
- Soil Dryness: When your plant’s soil is bone dry, it will take longer for bottom watering to work. Setting it in water for 20 minutes just isn’t going to cut it. Soil forms a waxy substance on the surface when it becomes too dry, and water will repel instead of soaking into the soil.
- Soil Amount: The larger the planter, the more soil mixture it houses and vice versa with small planters. Larger pots will take longer for the extra amount of soil to absorb enough water to moisten the roots of your plants. And smaller pots may only need 10 minutes to thoroughly wet the roots from the small amount of soil it contains.
So, you’ll need to consider these factors and leave it in water until you poke your finger in the soil and feel moistness, 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, the level should be at least 1 inch (2.5 cm) above the bottom of the soil. The capillary action of soil wicks the moisture upward against gravity to the root system.
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
Many sites have suggested using rocks to layer the bottom of the planter to assist with drainage, especially with planters with no drainage holes.
Not only will that cause the bottom watering method not to work, but it will also cause health issues for your plants. Studies have shown this theory is inaccurate because water does not drain from the soil due to rocks lining the bottom of your planter. Water accumulates at the bottom layer, known as the phreatic zone (or saturated zone).
The best explanation of the saturated zone is by thinking of a sponge soaked with water. When you turn the soaked sponge on any side, the water collects at the bottom of the lowest level side, and very little water will escape the sponge. The water in the saturated zone will stay wet for longer, unlike the rest of the sponge.
These results are the same with your soil since it absorbs water like a sponge. Adding a layer of rocks to the bottom of the planter lessens the amount of soil you add to the planter. Because the saturated zone remains the same no matter the level, the moisture area will be close to or within the root system with lessened soil.
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.
- Leaves are wilting or falling off.
- There is browning or yellowing of the leaves.
- The tips of the leaves appear ‘burnt.’
- White powdery residue on the top of the soil.
- Stunted blooming.
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 because it’s essential. Poking through the top of the soil will confirm the soil is wicking the water to the roots.
How To Prevent Complications When Bottom Watering
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 from 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 capillary action of the soil.
- If you need more holes for water absorption, you can add more holes by drilling or using another method.
- Have the correct soil media for your plants.
- Use the proper amendments for your soil mixture.
- Make sure nothing is clogging the drainage holes.
- If you have stones layering the bottom of the planter, remove them.
- Break up the mineral concentration 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.
I’ve written a related guide about fixing plants that do not absorb water from the bottom. I’ll specifically discuss why this problem occurs and go through some of the best options for fixing it. Don’t miss it: How To Fix Plants Not Absorbing Water From the Bottom
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.
To learn more on bottom watering, you could check out my other article here: How to Water Plants from the Bottom (Beginner’s Guide)