Do Orchids Like Acidic Soil?

Orchids are a well known, highly decorative plant that develops vibrant colors and can also assist in naturally purifying the air of its surroundings.

There are a whopping 28,000 different species of them. Some produce vanilla beans, some offer medicinal benefits, and most are used in decorative arrangements.

But, do orchids like acidic soil?

Well, most orchids prefer slightly acidic soil, usually between 5.5 and 6.5. But, one of their greatest challenges is maintaining balanced growing conditions to allow them to blossom and thrive. The toughest of these aspects to master is achieving an ideal soil pH. ​​

Do orchids like acidic soil

This can be achieved by combining the right ‘ingredients,’ which include the growing media, water, and fertilizer.

In this article, we’ll go through all the factors that can affect the soil’s pH, how to correct them if they are out of sync, and also how to create the perfect environment for growing orchids. 

Do orchids like acidic soil?

Most orchid species thrive best when grown in soil with a pH of between 5.5 and 6.5. It’s common to think that a magic chemical can alter soil levels, but that’s not the case.

There are a few factors that contribute to the base pH. Once the base is mastered, only then can the soil be corrected using slight changes.

Orchids need this specific pH level because any higher or lower will impact their ability to absorb nutrients. These plants rely heavily on a fertilization schedule to help them not only bloom but sprout out and spread. If they cannot take in these nutrients, they simply will not grow. 

Factors that affect soil pH for orchids

Orchids are pretty needy when it comes to achieving the right pH for them to thrive. Generally, a plant’s pH level is too low and frees up the soil’s aluminum stores. Aluminum is often attached to many soil components, especially clay and organic matter.

Factors that affect soil pH for orchids

Given that aluminum is not a plant nutrient, the higher amounts that are absorbed when the pH is low will stunt the growth of the roots. It will also prevent those roots from taking in the more important nutrients. Aluminum is essentially a blocker of growth! If the pH is too high, the plant nutrient molybdenum becomes prevalent in amounts considered toxic to plants.

This is why each plant needs to have the right pH balance to enable them to grow properly. The main factors that affect an orchid’s pH in its soil include the type of soil, the quality and frequency of water, and the amount of fertilizer. Let’s look at these factors in both natural and chemical variations. 

Natural factors that affect soil pH

Natural factors that affect soil pH

Rainwater and irrigation

As the rain begins its journey downward from above, its pH is neutral (7.0). However, when it passes through the atmosphere, it absorbs low pH contaminants at a fast pace.

Rainwater and irrigation

These contaminants are devoured by the soil and can leach into any plants grown within the same soil. Irrigation causes a greater volume of nitrates and other negative ions to absorb into the soil, which lowers the pH. 

Plant roots

Different plants absorb nitrogen or ammonium through their root system in different forms. Those that take in the growing mediums nitrogen as NO3- usually raise the pH in the rhizosphere. Plants that take in the ammonium as NH4 + or N2 lower the pH within the rhizosphere. Simply put, the plant type can change the pH of the soil without you even noticing it. 

Organic matter and compost

Due to decomposition, organic matter and compost have a higher content of organic acids. As the materials rot, they produce their acids, which delight growers. These acids naturally lower the pH of most soils that they are blended with. 

Chemical factors that affect soil pH

Fertilizers and pesticides

The nitrogen in fertilizers is the main culprit for affecting a soil’s pH levels. Nitrogen sources such as fertilizers, manures, legumes, etc., contain specific ammonium forms. This ingredient helps to increase the acidity of the soil unless the type of plant can take in the ammonium ions before it has the chance to acidify.

Fertilizers and pesticides

The more nitrogen based fertilizer that is present, the greater the rate of soil acidification can occur. Some pesticides can become diluted when added to a material or solution with a higher than base alkalinity (Anything above 7 pH). This process is called alkaline hydrolysis.

When this occurs, the plant will be either less protected or no longer protected by the pesticide. 

Acid rain

Acid rain is produced by the atmosphere’s emissions of sulfur dioxide and nitrogen oxides. Once these components react with rain, oxygen, and other airborne chemicals, they turn into sulfuric and nitric based acids.

When this rain reaches its final destination, anything it leaches into will generally have a pH below 4.5. Meaning the soil, water, plant life, etc. 

How to measure and adjust soil pH for orchids?

Whenever you want to adjust the pH of any plant’s soil, the first step that should be taken is testing the soil. This can be done using either a simple but effective pH litmus strip tester kit or a pH meter/probe. 

Litmus Strip Kit

These kits are quite inexpensive and pretty accurate. They are paper strips containing a special dye that changes color when a liquid solution is dripped onto them.

The color changes can be compared to a range chart (usually on the container for your convenience) to reveal the pH of the soil. 

Litmus Strip Kit

PH Meter

PH Meter

pH meters work similarly to the litmus strip kits. In this case, they are in digital probe form, which you dip into a solution based on the soil.

You then take a reading and adjust the pH of the soil accordingly. 

How do you take a pH reading of your soil when it isn’t liquid?

Since soil is not a liquid solution, you can follow these steps to obtain the result using soil.

How do you take a pH reading of your soil when it isn’t liquid
  1. Dig 4-6 inches into the soil you wish to test and remove enough of the soil to use as a sample (½ cup)
  2. Place 1-3 tsp of the soil into a clean glass.
  3. Add some distilled water to the soil (enough to become slightly more liquid than the soil)
  4. Give the mixture a stir
  5. Remove as much soil as you can so that mostly water remains. 
  6. Use the pH tester (litmus strip kit or meter/probe) to take a reading.
  7. Adjust the pH accordingly. 

Adjusting the soils pH using lime or sulfur

Once you have completed your testing and are satisfied with the results, you can adjust the pH using some easily obtainable products. The simplest to use is lime and sulfur. Lime is used to raise the soil’s pH, and sulfur is used to lower it. Neither of the 2 products is water soluble, so they must be blended into the top 15 cm of soil once watered for them to work quickly and effectively. 

How to create the right soil environment for orchids?

Orchids are epiphytic plants. Their roots need a decent amount of aeration and drainage under the soil and surrounding areas to survive. The reality is that regular soil blends are far too dense to support an orchid’s intricate root system, eventually suffocating the plant.

Furthermore, If the roots are left to bathe in stagnant pooling water for too long, they will rot. As much as orchids love water, they should never be overwatered, especially in the soil much too absorbent. Therefore, the soil composition of an orchid is extremely important. 

There are generally 3 main factors contribute to the health of an orchid’s soil. These factors are their growing media, amount and water frequency, and fertilization schedule. 

Growing Media

Firstly, the growing media used needs to offer adequate aeration and drainage. It should be light and loose and allow the roots the freedom to move around and establish themselves. They should never be allowed to be suffocated.

orchid growing media

Materials such as perlite, vermiculite, or lava rocks can be mixed into organic matter in peat moss, fir bark, dried fern roots, sphagnum moss, or even rock wool to help achieve this. This base will allow the next element to function without a hitch. 


As mentioned, orchids love good watering. However, they shouldn’t be drowned in the wet stuff. Watering them every 7-10 days is usually around the right frequency. However, many environmental factors can alter this time frame.


For example, warmer temperatures and excessive winds will dry the soil much faster. If unsure when to water, you can always do the simple finger test. Stick your finger down the side of the plant about 2-3 inches into the soil; if it comes out dry, you can safely water your orchid.

If any moisture is present, allow it an extra day to dry out. Excessive watering will cause problems such as root rot, leading to fungus gnat infestations if left unattended. 


Orchids enjoy a good feed. However, too much or strong fertilizer can burn an orchid’s leaves and roots. Generally, aim to feed your plants every 2 weeks during their peak growth seasons (spring and summer). Then scale down to around once per month during their dormancy period (fall and winter).


It’s recommended to use a 30-10-10 fertilizer or a specially formulated orchid food diluted at half its strength. Leading up to the orchid’s bloom period, it’s best to use a more balanced fertilizer, like 20-20-20. This will ensure they are not taking in too much nitrogen. 

Frequently Asked Questions (FAQs)

Is tap water OK for orchids?

It’s always recommended that you use collected rain or distilled water to water your orchids. Most tap waters are softened and contain salts that can cause significant damage to the plant. Chlorinated tap water can be ok to use, provided the chlorine isn’t excessive, which can be tricky to distinguish without any professional tools.

Can you spray orchids with soapy water?

It is ok to use soapy water in orchids as long as the detergent is diluted. Higher amounts of detergent can cause irreversible damage to your plants, especially their buds and flowers.

Should I mist my orchids?

Orchids are tropical plants used to humid conditions, so they don’t mind being misted. This can be done by adding some water to a spray bottle and ensuring the nozzle is set tighter, producing more of a mist than a heavy spray. 

What is the perfect pH for Orchids?

Most orchid species thrive best when their soil pH is between 5.5-6.5 (slightly acidic).


Orchids are generally pain free to maintain. However, ensuring they have the right balance of soil characteristics is crucial to their longevity. The key points to master are providing the soil with adequate aeration and drainage.

This will ensure that their food and water sources can be delivered to them without restrictions. We hope that this guide has been helpful. You can read about similar topics here on our website. Check back again soon for more.

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