So you took the leap and bought that houseplant you always wanted. In fact, that interior decorating shot you saw on a social media post, ‘inspired’ you to get a few. And why not? Plants make us happy! They increase the indoor oxygen and filter air too. You also made sure to buy only houseplants that are safe for babies and pets, since you share the house with others. This is good news and all very exciting. A life with plants can be a very rewarding one. As with many things in life we discover and learn new things on the way. This of course is true about houseplants too. One of the things you will discover is how important the condition of the soil is. However, the scope of this article only focuses on the importance of the pH of the soil and the houseplants that like acidic soil.
What is pH and why is it important for houseplants?
pH is the scale used to measure soil acidity. It runs from 0 to 10, with 7 representing the neutral point. Anything below 7 represents acidity and everything above 7 is alkaline. Houseplants that like acidic soil need a soil pH of about 6.5 and below.
If your plant is not looking too great, has yellowing of leaves, looks straggly, or hardly growing at all, you might suspect everything else, except the soil’s pH levels. The truth is that the right pH for your houseplants is crucial if you want them to stay healthy and flourish. This is because the right pH allows the plant to effectively absorb all the vital nutrients it needs to be happy. Nutrients vital for plant health include iron, manganese, phosphorous, copper, and zinc. Making any one of these nutrients available in large quantities to certain plants by raising or lowering the pH, may poison them. For example, when soil pH is too low for Geraniums, high levels of manganese made available, becomes toxic to the plant. Conversely, the higher pH levels will set free toxic levels of molybdenum.
Houseplants that like acidic soil also depend on the creatures and organisms living in the soil. They are vital when it comes to healthy soil and plants and need slightly acidic conditions to thrive.
How to test the pH of houseplants that like acidic soil
Whether you have houseplants that like acidic soil living indoors or outside in the garden, testing the soil’s pH is easy. Try any of the following methods:
- Place 2 tablespoons of sample soil into a clean glass and add ½ a cup of vinegar to make it a little muddy. Observe how the vinegar reacts with the soil. If it fizzes or foams, your soil is alkaline.
- Place 2 tablespoons of sample soil into a clean glass and make it moist with distilled water. Then add ½ a cup of bicarbonate of soda. This time, if it fizzes or foams, you will know that the soil is acidic.
- You can also make use of pH strips. Place 2 tablespoons of sample soil into a clean glass. Add just enough distilled water so that it is the same level as the soil. Stir the soil and then let it rest for about half an hour. Filter through a paper coffee filter into a clean glass. Dip a pH strip and check the color to determine the pH. To get an average soil pH for your garden, repeat the same process but collecting soil samples from a few different areas around the garden.
How to adjust the soil pH for houseplants.
You can raise or lower the soil’s pH by simply adding one of 2 compounds.
To raise the pH, you can add limestone. There are two types of limestone, namely calcium carbonate and dolomitic limestone. Of these two, dolomitic is preferred as it also contains magnesium which is great for the soil and also neutralises acidity better.
Houseplants that like acidic soil
Fortunately, most houseplants prefer soil to be on the acidic side. Find your favorite houseplants that like acidic soil from the list below as well as the corresponding pH levels for each plant.
|African Violet||5.8 to 6.2|
|Amaryllis||6.0 to 6.8|
|Andromeda||5.0 to 6.5|
|Anthurium||5.0 to 5.5|
|Arrowhead Vine||5.5 to 6.5|
|Aster||5.8 to 6.75|
|Astilbe||6.0 to 8.0|
|Azalea||4.5 to 5.5|
|Basil||5.1 to 8.5|
|Begonias||5.5 to 6.2|
|Bird’s Nest Fern||5.0 to 5.5|
|Bleeding heart||6.0 to 6.5|
|Cactus||5.0 to 7.0|
|Caladium||5.5 to 6.5|
|Catnip||6.0 to 7.5|
|Camellia||6.0 to 6.5|
|Chinese Evergreen||5.5 to 6.0|
|Croton||4.5 to 6.5|
|Daffodils||6.0 to 7.0|
|English Ivy||5.5 to 6.5|
|Ferns||4.0 to 7.0|
|Gardenia||4.5 to 5.5|
|Heath||5.5 to 6.5|
|Hibiscus||5.5 to 7.5|
|Holly||4.5 to 5.5|
|Hydrangea||5.0 to 6.5|
|Iris||5.5 to 7.5|
|Japanese Pieris||5.0 to 6.0|
|Lily of the Valley||5.0 to 6.0|
|Southern Magnolia||5.0 to 6.5|
|Marigold||5.6 to 7.5|
|Monstera||5.5 to 7.0|
|Nasturtium||5.5 to 7.5|
|Peace Lily||5.0 to 6.5|
|Peperomia||5.0 to 6.0|
|Philodendron||5.0 to 6.0|
|Rhododendron||4.5 to 5.5|
|Rubber Plant||4.0 to 6.5|
|Snake Plant||4.5 to 8.5|
|Yucca||4.5 to 6.5|
Last thoughts on houseplants that like acidic soil
It is not hard to keep houseplants that like acidic soil healthy and happy, by monitoring the pH of the soil regularly. Since, fertilizer can change the soil’s pH again over time, you may have to add either limestone or sulfur to keep things in the right shape.
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