Bottom watering is an excellent way to water your houseplants and keep the root system evenly moist. This process allows plants to soak up the right amount of water, especially when soil is compacted and hydrophobic. But sometimes it’s difficult to know when they’re fully watered, so how long should you let them sit?
Plants should sit for about 10 to 30 minutes while bottom watering, depending on the soil dryness, pot size, and soil type. After 10 minutes, check the soil by pushing your finger in it near the edge of the pot. If it’s still dry once you’ve reached your second knuckle, it needs to soak longer.
This article will explore bottom watering, its pros and cons, and other tips to keep your plants happy and thrive in their potted environment.
How Bottom Watering Works
Bottom watering is a method that allows the plant’s soil to absorb water through the drainage holes in the bottom of the pot up to the roots. This method enables the soil to absorb the water needed to moisten the root system uniformly.
The amount and frequency of water uptake from your plants depend on the plant itself, the season, and the amount of sunlight available.
For this method to be effective, check the soil weekly instead of having a set routine. To do this, stick a finger in the soil up to the second knuckle. If the soil is dry, it likely needs to be watered (depending on your chosen plant’s needs), but if it’s moist, you can wait a few days and recheck it.
Since you’re checking the soil frequently, you’ll provide your plants with the water they need instead of accidentally over or underwatering them by using a routine for top watering.
When using this method, you’re also saving the nutrients contained in the soil. When you top water plants, the water trickles through the soil and flushes the nutrients to the bottom and out of the drainage holes. Bottom watering pulls the water into the soil, upward to the root system, keeping the nutrients in the soil.
However, you will need to periodically top water your plants to break up the concentration of nutrients and excess salts that can occur from bottom watering.
Pros and Cons of Bottom Watering
Like any gardening technique, bottom watering is highly beneficial when done right but can be detrimental when done incorrectly. There’s no clear-cut rule on the duration of bottom watering as several factors can influence it.
Still, it’s crucial to understand the pros and cons of this watering method to encourage new or experienced gardeners to do it properly.
Bottom watering has more pros than cons and is the preferred method of watering for many plant lovers because of its effectiveness.
Here are some of the pros:
- Bottom watering is especially effective for very dry soil, providing uniform water distribution to the root system and promoting healthy development and spread.
- Bottom watering limits problems with overwatering or underwatering that cause stress on your plants and plant roots.
- With bottom watering, there’s no risk of splashing water on the leaves of sensitive plants, such as African violets, reducing problems with disease.
- When bottom watering, you can still add fertilizer by mixing it in the water before submerging your pots.
- With bottom watering, you don’t have those awful, annoying fungus gnats or other pests playing in moist topsoil.
- Bottom watering is super easy, less messy, and you probably already have everything you need. You don’t need any fancy tools or supplies. You can use bowls, buckets, a sink, or anything else you can fill with water and set your plants in.
As with most things in life, you should consider the good with the bad, and bottom watering has very few cons:
- With bottom watering, there’s a chance you can overwater your plants if you forget about them as they’re soaking in water.
- If the soil has become soggy at the bottom of the pot, you’ll risk damage to the root system if it sits for too long. If this happens, immediately remove your plants from the water and place them on a folded towel to draw out excess water. You can also gently pull your plants from the pot and wrap the towel around them to absorb more water faster.
- With bottom watering, the nutrients in the soil can build up over time, so the soil should be flushed from the top about once a month.
- Not all soil will effectively absorb the water to moisten the roots in a uniform fashion by bottom watering. Soil that’s compacted or has a higher ratio of clay in the mix will give you complications when bottom watering. It’s best to use soil with materials that aerate and provide sufficient drainage to protect the root system from suffering root rot.
Recommended Duration: 10-30 Minutes
On average, plants should sit for about 10 to 30 minutes while bottom watering.
The exact time will differ depending on several factors, including:
As discussed, it’s time to start bottom watering when the soil is dry beyond two knuckles after the finger test. The amount of moisture left in the pot beyond that point can determine how quickly the soil can absorb water.
Wider and deeper pots contain more soil or potting mix, requiring a longer soaking time to adequately saturate the growing medium.
Unglazed clay or terracotta pots are likely to absorb moisture more quickly due to their porosity. However, this could also mean that you’ll need to bottom water your plant more frequently because the moisture will evaporate more quickly.
In contrast, plastic pots depend only on the drainage hole at the bottom to absorb water, making the process slower. It’s also likely that the soil will dry out more slowly.
Soil Type or Potting Mix Components
Materials with high water retention capacity, such as loamy soil, coco peat, and vermiculite, tend to absorb and hold water more quickly.
Plants with fibrous roots are more efficient in absorbing water from the soil because of finer roots with higher capillary action potential that speed up the absorption of water into the substrate.
On the other hand, plants with fleshy roots are likely to take longer to pull enough water to saturate the soil. This extended duration increases the risk of root rot.
Larger potted plants with extensive fibrous root networks typically require a shorter time to absorb water and adequately saturate the soil.
Monitor Your Session Closely
A combination of these factors can significantly affect how long bottom watering takes. Therefore, it’s crucial to manually check your soil’s moisture content. After 10 minutes, check the soil by pushing your finger in it near the edge of the pot.
Ideally, the soil should be moist up to the surface or at least a knuckle (1 inch or 2.5 cm) below the surface. If it’s still dry, leave the pot to draw up more moisture. Continue to check every 5 minutes and remember not to leave the pots sitting in water longer than 30 minutes.
If it requires longer than 30 minutes, you may need to check your soil’s condition and make amendments, as it may have become compacted or hydrophobic.
Tips to Effectively Bottom Water Plants
While this is an easy technique to incorporate, having the pots for your plants will help prevent bottom watering problems.
Find the Right Pot Size and Type
Plant pots come in different sizes and types, but they should all have drainage holes that allow excess moisture to leave the container, and water to flow through the soil when bottom watering.
The size of the pot also matters because the larger the pot, the longer it takes to absorb enough water to moisten the root system. That’s why it’s imperative to check the soil for moistness, as mentioned earlier.
If you have porous planters, such as clay or wood, the materials will also soak up the water, meaning it will take less time to bottom water.
Porous pots like terracotta pots should still have at least one drainage hole in the center of the bottom of the pot. That’s typically sufficient for proper drainage, as the pot itself helps evaporate moisture in the soil.
Make sure you take these factors into account when considering how long your pot should sit in the water.
Use a Self-Watering Planter
You can also purchase self-watering planters that use the same bottom-watering technique. There are different designs of this type of planter, with some being relatively cheap. But they all share the goal of allowing you to water a bottom tray or bowl to effectively bottom water your plants without having to gather them all up to place in a tray or sink.
Some of these bottom watering pots are plastic with a pop-off tray at the bottom. Some designs include a porous earth material pot that sits inside another pot you fill with water. Either of these choices will help you keep your plants evenly watered and happy, and you just have to choose which type is suitable for you and your plants.
Bottom watering your houseplants is one of the most effective methods, as it provides an even water distribution to the roots. This method typically takes about 10 to 30 minutes, and while there’s no set routine for watering utilizing this method, you should have a routine of checking the soil weekly to see if watering is needed.
You can water several plants at once by setting them in a tray, sink, or tub to soak up the water. However, always flush the soil about once a month by top watering to prevent salt buildup that can burn your plants.