Bottom Watering Soil: 5 Benefits Bottom Watering has on Soil


Share this article

Bottom watering is becoming the new favorite thing when it comes to watering potted plants. It is an effective technique to water the plant from the bottom up without over saturating the soil. 

A good bottom watering soil should have good aeration and spaces for the water to be properly absorbed when the plant is being bottom watered. The effect bottom watering has on soil is that it moistens the soil and allows stale air to be pushed out by the water during the process and fresh air to be drawn back in when the water is drained.

However, If you would like to know how bottom watering affects soil, prevents root rot and fungus gnats this article will explain everything you need to know.

What is Bottom Watering?

Bottom watering is done by placing the plant in a tray of water at approximately 1 to 2 inches high. The water is then absorbed into the soil from the bottom up after which it is allowed to drain freely leaving the soil moist and aerated.

Bottom watering :

  • Stimulates healthy root growth
  • Prevents pests such as gnats
  • Prevents overwatering
  • Allows fresh air into the soil
Bottom watering plants infographic

How Bottom Watering Affects Soil?

With bottom watering, you don’t have to be worried about problems like overwatering and underwatering. Your plant will only soak up as much water it needs for normal functioning.

See our our complete guide for bottom watering plants which gives easy to understand details with step by step instructions.

In this technique, you place your plant pot with a drainage hole in a water basin that has a few inches of water in it. 

The plants’ roots absorb the water according to their requirements for normal functioning, neither less nor more. 

Bottom watering affects soil in various ways. Some are listed below.

Uniformly Waters The Plant

Bottom watering is an effective way to keep the soil and roots moist. It doesn’t wash away the salt and mineral deposits of soil. Thus, providing soil a uniform texture.  

Bottom watering uniformly waters the plants and ensures that the water has reached all parts of the irrigated zone. 

Prevent Soil Compaction

Soil compaction is the hardening of soil. When you top water your potting soil, it becomes wet and eventually hardens which results in soil compaction. 

Plants do not grow well in compacted soil because the roots can’t grow well, resulting in plants’ death.

The bottom is an effective method to avoid soil compaction. Therefore, if your potting soil easily gets compacted, you should bottom water the plant instead of top watering. 

By bottom watering, the water will be directly provided to the roots. The soil will be soft and plant roots will grow freely in any direction they want. 

However, if the entire soil mass is compacted then the bottom watering process may not work.

Improve Soil Aeration

Soil aeration plays an important role in plant normal growth. Soil aeration helps to exchange gases like carbon dioxide and oxygen between the soil pore spaces and the atmosphere.

When soil becomes compact, it’s hard for plants and for soil as well to exchange the gases. So it will result in the death of plants as these glasses are vital for plant survival. 

Bottom watering also aids in improving soil aeration and helps in a rapid exchange of these gases between soil and the atmosphere. 

When there will be a proper circulation of gases between plants and the atmosphere, bringing vital o² to the root zone, the plants will grow well.

Promotes a Healthy Microorganisms Population

There are certain microorganisms (such as bacteria, protozoa, fungi, actinomycetes, and nematodes) present in the soil that are beneficial for a plant’s proper growth. 

Their aim is to create a symbiotic association with the roots of plants. The microorganisms are also known as microbes. 

These microorganisms boost soil and plant health by producing plant growth hormones and shielding plants against potential fungus infections and pests. 

Bottom watering helps in promoting these microorganisms as they are also responsible for promoting nutrient mineralization to plants which is not possible with top watering.

Prevents Gnats

Bottom watering prevents gnats by reducing the moisture content at the surface of the soil. Fungus gnats live and reproduce in moist soil where they feed on damp, organic material.

Watering from the bottom reduces the moisture content at the surface of the soil, hence deterring fungus gnats in potted plants.

I use this Miracle-Gro Potting Mix from amazon, which ensures my plants stay healthy long after repotting. You can find it by clicking here.

repotting a root bound plant

Does Bottom Watering Prevent Root Rot?

There are many causes of root rot. The main causes include poor functioning of the root system, overwatering, water logging due to prolonged exposure to excess water. 

This problem can be solved by providing an adequate amount of water to plants. The bottom watering technique can assure you that the plant gets the required amount of water, not less or not more. 

Bottom watering allows the soil to remain moist for a period which enables plants and seedlings to get only the amount of water that is required for proper growth and development.

By using a simple touch test you can determine when to remove the plant from the tray. We have found this period to usually be between 15 to 20 minutes for most plants.

Furthermore, bottom watering also prevents soil from waterlogging and saves the plant’s roots from decaying. 

Does Bottom Watering Prevent Pests?

Bottom watering keeps the surface moist for a short period, allowing the leaves to flourish by decreasing pests’ development.

A house with houseplants is heaven to shore flies and gnats. Fungus gnats belong to the family Mycetophilidae and Sciaridae, one of the pure insects. 

These mosquito-like insects are considered one of the most dangerous pests of houseplants.

Adult fungus gnats, especially egg-laying adult females, are highly attracted to moist growing mediums of houseplants. 

Larvae of fungus gnats commonly feed on fungi, algae, and soft roots. 

Thus, making the growing medium of houseplants heaven for laid eggs or larvae growth. 

One of the most effective strategies to prevent fungus gnats and other pests around your houseplants is by allowing the growing medium to dry up completely between watering, especially the topsoil. 

The dry topsoil will minimize the survival of any moist-loving pest. 

Bottom watering prevents gnats from infesting the plant’s soil by not allowing water to accumulate at the surface for prolonged periods. 

Unlike top watering, where gardeners drench the topsoil with water. 

Soil That Bottom Watering Works Well With 

Not all soil types or potting mixes can work well with bottom watering. Particularly, soil that is too compact or has a high clay ratio does not work well with bottom watering. 

We have compiled a short-list of soil with which bottom watering works ideally:

Potting Soil

Potting soil is best for bottom watering plants as it is specifically prepared for pot plants. It is rough in texture and appears dark in appearance. 

Potting soil comprises sand, perlite, peat moss, vermiculite, pebbles. 

It’s best for bottom watering because it doesn’t stay moist for a lot of time. 

Yellow miracle grow potting mix

Well-Draining Soil

The vital thing in well-drained soil is oxygen. Well-draining soil is best for bottom watering. Well-drained soil includes loam (clay 20% and silt 40%), sandy soil. 

You can prepare well-drained soil at home by just following the points given below.

  • Dig the soil using a shovel and try to lose the soil as much as possible.
  • Add compost material like clay and sandy soil. 
  • The more you dig the bed of soil the more you will get the better quality of the soil. 

Well-drained soil helps in the infiltration process (movement of water into the soil) and in the process of percolation (downward movement of water within the soil). 

Soil With a High Ratio of Amendment

Bottom watering also works well in the soil which has a high ratio of compost material or soil amendments in it. 

Sandy soil has a great amendment known as sphagnum peat which is acidic in nature and is beneficial for those plants which love to grow in more acidic soil.

Soil That is Not Suited For Bottom Watering 

As we mentioned earlier, bottom watering will not work with every type of soil. bottom watering requires well-drained soil to work well with. 

Soil With Bad Drainage

Soil with bad drainage is not ideal for bottom watering. Because water will not be able to reach all parts of the irrigated zone and to the plant. 

So one should check whether the soil is well-drained or not before bottom watering the plants.

To test the moisture and pH of the soil you can use the cost-effective Trazon Soil 3-in-1 Meter. It not only tests for pH but also moisture content and light intensity. You can find it by clicking here!

Trazon Soil pH Meter 3-in-1 Soil Tester Moisture

Soil With High Clay Content

The soil with high clay content includes clay, silty clay, clay loam, sandy clay, etc, and is not a good choice for bottom watering. 

In this type of soil, bottom watering does not function well. In other words, this soil is not suited for bottom watering. 

The Takeaway

Bottom watering can benefit your plant’s soil in more than one way. It not only prevents overwatering and pests but also boosts the aeration and growth of healthy microbes. 

With bottom watering, you don’t have to worry about problems like underwatering, overwatering, waterlogging, or root rot.  

JayLea

JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

Posts to pique your interest