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Rising environmental concerns are leading many people to seek out peat-free Ericaceous compost to grow their own plantsacid-loving plants.
But how do you make peat-free bog compost?
The best substitute for peat when making heather compost is sulfur or coir. However, other biodegradable organic materials such as pine needles, pine bark, oak leaves, coffee grounds, vinegar, lemon juice, or even aquarium water are not effective at significantly lowering soil pH over the long term.
If you want to know why these two are alternatives to peat and why the others don't work, read on.
Table of contents
1. What is Ericaceous Compost?
"Ericaceous" refers toEricaceae, or the heather family, consisting of over 1900 species ranging from alpine herbs to large tropical trees.
These plants prefer to grow in soil with a pH of 4.5 - 5.5, which is much more acidic than the pH preference of most plants in the pH 6 - 7 range " designated.
The growing medium suitable for growing such acid-loving plants is therefore called “Ericaceae Compost”, which typically has a pH of 4.5 – 5.5.
There is no single, specific recipe for making bog compost. Heather compost is easy to makeMixing acid-forming substances, which can be minerals or organic matter, into the soil to achieve a low pH for acid-loving plants.
2. Heather compost vs regular compost
heather compostprepared at the location of the acid-loving plantAnddoes not require decomposition before use, unlike regular compost which takes several months to decompose and mature before it can be used.
Because of such a difference, the pH of normal compost returns to almost neutral at the end of the decomposition process.
3. Why do we need heather compost?
acid-loving plants, including plants from the heather family, need to be grown in soil with a pH of 4.5-5.5, which is much more acidic than what most plants prefer.
That's becauseAcid loving plants have much higher requirements for certain minerals such as manganese (Mn) and iron (Fe), which are most available in highly acidic environments.
However, most plants do not need much iron or manganese and can get by with the small amounts their roots can absorb.
Iron and manganese are required for photosynthesis and chlorophyll production, and a lack of these would cause chlorosis, or yellowing of the leaves.
Heather compost can thus lower the pH of the soil, making such minerals more soluble and available for the plant to absorb immediately.
3.1 Coco Coir for pots
Coconut fibers or coconut shell fibers are suitable for potted plantsthe best natural alternative toTorfmoosin acidifying the soil and improving nutrient uptake for acid loving plants.
This is demonstrated by an experiment comparing the use of 20% peat versus 20% coir to change the pH of a bark growth medium for 16 weeks (Scagel, 2003).
The results show that although coco coir does not lower the pH of the growing medium as much as peat, a coco coir-enriched medium doesequal availability of Magnesium (Mg), Iron (Fe) and Boron (B) minerals and even better availability of nutrients including Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Sulfur (S)for immediate ingestion as a peat-enriched medium.
The result was a coco-spiked mediumslightly weaker roots but stronger stems, compared to the peat-spiked medium.
To make heather compost from coir,Mix 1 part coco coir with 1 part garden soil orregular compost.
3.2 Sulfur for beds
Elemental sulfur is most effective at lowering soil pH for acidifying a large amount of soil, such as for use outdoors in garden beds. Using coir would not be economical for a large area as it would take a lot to change just a tenth of a pH.
To apply until2 pounds of sulfur in the top 12 inches of soil per 100 square feet. Repeat at least one more time a year later. And check the pH of the soil before reapplying.
Changing soil pH is a slow process because soil bacteria convert the sulfur in the soil (or compost) into sulfuric acid (H2SO4), and the process can take up to a year.
The best time to apply sulfur is in spring and summerwhen the floor temperature is above 13 °C,and when soil bacteria are more active. This can reduce the time required by more than half.
Other forms of sulfur, such asFerrous Sulphate (FeSO4)AndAluminiumsulfat (Al2(SO4)3), can achieve faster results and lower the pH within a day. However, this can shock the existing plants (e.g. lawn) and the microorganisms in the soil. It would also require the use of up to five times more chemicals than elemental sulfur as it is easily leached. And using such chemicals is incompatible with organic gardening.
4. What doesn't work?
There are many suggestions for using various organics to lower soil pH, but most biodegradable organics will not work.
4.1 Pine bark, pine needles, sawdust
One of the popular gardening myths for acidifying the soil is composting or mulching with pine bark, pine needles, or even sawdust.
It is true that fresh green pine needles on the tree have a pH of 3.2 to 3.8. ButTheir pH drops as they mature and fall from the tree. As they decompose in the soil and turn brown, their pH will quickly return to the neutral range within a few days.
Pine bark, pine dust, and other wood shavings have a similar problem: it wouldrequire that dumpster loads show measurable changes, and the pH quickly returns to the neutral state as they decompose.
4.2 True Leaves
Another gardening myth is that leaves from deciduous trees like oak, maple, and beech can acidify soils.
Using vinegar (which typically has a pH of 2.4) to acidify the soil is immediate, within hours of application.
Do not put vinegar directly into the soil as it is too acidic and can shock existing plants and soil microbes. Instead, dilute a cup of vinegar in a gallon of water and use the solution to water the soil.
The acidifying effect of vinegar, on the other hand, isnot permanent as it degrades quickly in the soil. In addition, the acidity is rapidly degraded further by precipitation and subsequent watering.
It would require frequent applications and you would need to check the soil pH every few days.
4.4 Lemon/Lime Juice
Using concentrated lemon and lime juice to acidify the soil is also an ineffective and short-term method. Although they have a low pH and can be used diluted with water, their acidity is quickly reduced by rain and watering.
4.5 Coffee Grounds
Using coffee grounds to acidify the soil is ineffective and unreliable becauseOnly fresh, unused coffee grounds are sour. Used coffee grounds have a near-neutral pH because most of the acids have migrated into the beverage.
The acidifying effect of fresh coffee grounds is also short-lived, as the acid is water-soluble and is washed out of the soil after repeated watering.
You should also know that the caffeine in coffee can suppress seed germination and stunt plant growth.
The water in poorly maintained aquariums that is not changed often is usually slightly acidic due to the organic waste produced by the fish. However,It would take a lot of aquarium water to cause a significant and long-term change in soil pH.
Another problem with aquarium water is its putrid odor, which is not ideal for indoor plants. And such water can carry pathogens that would not be optimal for use in the vegetable garden.
5. Does Ericaceous compost lose acidity over time?
Yes. All types of heather compost lose acidity over time and become neutral as the compost maturesin six months to a year.
Using heather compost to acidify the soil would therefore require repeated application every six months or every year depending on the ingredients in the compost.
Compost containing sulfur is the most stable and can remain acidic for up to two years.
6. Does Ericaceous compost work with pots?
Heather compost works well with acid loving plants in pots. In fact, it can be easier to grow such plants in outdoor containers in places where the soil is not acidic enough or even alkaline.
This is because changing the pH of the soil in large areas such as garden beds requires multiple applications of ericaceous compost every 6 months and frequent checks to monitor the pH of the soil from time to time.
Fill the pot or container with a mixture of equal amounts of heather soil and coarse sand.
7. Is Multipurpose Compost Ericaceous?
Multipurpose compost is not and is not a bog bedonly slightly acidic to pH-neutral.
Multipurpose compost can improve water retention and soil aeration. But it's not acidic enough for ericaceous plants.
8. Can I use heather compost for all plants?
It isIt is not recommended to use heather soil (with pH 4.5-5.5) for all plantsbecause different plants have different pH preferences and tolerances.
Most plants only require a slightly acidic growing environment (pH 6-7) and will struggle to absorb nutrients in a highly acidic medium.
Some plants (e.g. lavender, thyme) even prefer slightly alkaline soil and will therefore have difficulty growing in soil enriched with ericaceous compost.
9. Use of Ericaceous Compost in Gardens
Depending on the type of soil in your garden, you can use bog compost in the garden in different ways.
If your garden soil is neutral or slightly acidic, you can do thatWork compost into the topsoil or lay it on the surface as a mulch, and the organic organisms will eventually incorporate it into the soil.
Or you canmake raised bedsfor your acid-loving plants. Fill the beds with aMixture of equal amounts of garden soil, heather compost and part coarse sand.
If done right, raised beds allow you to grow both ericaceous plants and alkali-loving plants in the same garden.
The best peat-free heather compost uses sulfur or coir to acidify the soil.
However, other organic materials such as pine needles and bark, wood shavings, sawdust, coffee grounds, oak leaves, citrus juice, vinegar, aquarium water are not effective in sustaining significant and long-term changes in soil pH.
Top 41 Acid Loving Plants (List A to Z)
BBC Gardeners‘ World Magazine. (2021).Heather compost.
Oregon State University (2017).Myth vs Reality: What's the Truth Behind Some Common Gardening Practices?
Winkler, M. G. & DeWitt, C. B. (2009).Environmental Impacts of Peat Extraction in the United States: Wetland Conservation Documentation | environmental Protection.Cambridge Core.
Layman, K., Dunn, B. & Arnall, B. (2018).Identifying and Resolving Iron Deficiency in Ornamental Plants - Oklahoma State University. State University of Oklahoma.
Longstroth, M. (nd).Lower the pH of the soil with sulfur.Extension of Michigan State University.
Morrissey, J. & Guerinot, ML (2010).Iron Uptake and Transport in Plants: The Good, the Bad, and the Ionome.Chem Rev. Oct. 2009; 109(10): 4553–4567.
Scagel, CF (2003).Growth and nutrient consumption of Ericaceae plants grown in media modified with sphagnum moss, peat or coco dust.American Society for Horticultural Sciences.