Do you know that a small number of plants need to grow in highly acidic soil because they have a higher requirement of certain nutrients that are most available in low pH environments?
While most plants thrive in slightly acidic or near-neutral soil, a small number of herb, vegetable, ornamental flowers, shrub and trees, actually need to grow in highly acidic soil with a 4.5 to 5.5 pH.
In this article, we put together such a list of 41 popular acid-loving plants that can be grown in very acidic soil (pH 4.5 – 6), or Ericaceous soil, and in soil that is near neutral (pH 6 – 7).
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These are the plants that need highly acidic soil (pH 4.5-5.5).
What affects the pH preferences of plants?
Several factors influence the pH preferences of plants, as the pH level of the soil can impact nutrient availability, chemical reactions, and microbial activity. Some of the main factors affecting a plant’s pH preference include:
- Plant species: Different plant species have evolved in various environments and are adapted to specific pH ranges. For example, acid-loving plants like azaleas, blueberries, and rhododendrons prefer a pH range of 4.5 to 5.5, while most vegetables and flowers grow best in slightly acidic to neutral soil with a pH of 6.0 to 7.0. Also, different species of plants from the same family can result in different pH preferences. For example, both Fraser fir and Balsam fir trees prefer a highly acidic 4.5-5 pH and 5-6 pH environment respectively, while Douglas fir trees prefer a less acidic environment of 6-7 pH. The same goes with double-file viburnum (6.5-7.5 pH) and maple-leaved viburnum (4-5 pH) which have different pH requirements.
- Nutrient availability: The availability of essential nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, and micronutrients like iron, manganese, zinc, and copper, is influenced by soil pH. Some nutrients are more available in acidic soils, while others are more available in alkaline soils. Plants have evolved to prefer specific pH levels that provide optimal nutrient availability for their growth.
- Soil type: The soil’s composition, including its mineral content, organic matter, and texture, can impact the pH preference of plants. For example, sandy soils tend to be more acidic, while clay soils are often alkaline. The soil’s buffering capacity, which refers to its ability to resist changes in pH, also plays a role in determining the optimal pH range for plant growth.
- Microbial activity: Soil pH affects the activity of beneficial microorganisms that contribute to nutrient cycling, decomposition of organic matter, and nitrogen fixation. Some plants prefer specific pH levels that promote the growth of symbiotic microbes, such as legumes that rely on Rhizobium bacteria for nitrogen fixation.
- Climate: Regional climate can influence soil pH and plant preferences. In areas with high rainfall, the soil tends to be more acidic due to leaching of basic elements like calcium and magnesium. In arid regions, soil pH tends to be more alkaline due to the accumulation of salts and carbonates.
- Parent material: The parent material from which the soil is derived, such as bedrock or deposited sediments, can influence soil pH and plant preferences. For example, soils derived from limestone tend to be more alkaline, while those formed from granite or sandstone are typically more acidic.
Understanding the factors affecting the pH preferences of plants is crucial for successful gardening or farming, as it helps in selecting the right plants for a particular environment and managing soil conditions to optimize plant growth and health.
Let’s take a look at the list of acid-loving plants.
Most herbs require only slightly acidic soil.
|Fringed bleeding heart||6-6.5|
2. Vegetable and crops
The majority of vegetables require only slightly acidic soil, with potatoes and sweet potatoes as the few exceptions.
Rhubarb is quite unique in its soil pH preference as it can grow in highly acidic, neutral as well as alkaline soil, as long as it is well drained.
|Peppers, sweet or hot||6-7 ok|
|Pumpkin and winter squash (and vine crops)||6-6.5|
Most fruits require only slightly acidic soil, with apple and berries as the exception in preferring highly acidic soil.
|Red clover||At least 6.5|
Many flowers require highly acidic soil, including houseplants such as African violets.
|Red clover||At least 6.5|
5. Shrubs and Vines
Many shrubs require highly acidic soil, especially most Heather species.
Heather is a small summer-flowering shrub in the Ericaceae family that requires Ericaceous or highly acidic soil. However, some Heather species, which flower in winter and spring, can thrive in acidic, neutral and even alkaline soil as long as the soil is not too low on Magnesium and is well-draining. Examples include: Erica vagans (cornish heath), Erica carnea (Mountain heath), Erica erigena (Irish heath), Erica x darleyensis, Erica x griffithsii.
Hydrangeas will display shades of deep blue (pH 4.5), medium blue (pH 5), lavender purple (pH 5.5), purple pink (pH 6), medium pink (pH 6.5) and deep pink (pH 7). This is because the blue-colored mineral, aluminium, in the soil is most readily available for root uptake at a lower pH. If the soil goes above pH 6.4, Hydrangeas may even experience iron deficiency.
|Rose, hybrid tea||5.5-7|
|Viburnum, double file||6.5-7.5|
Almost all evergreen trees need to grow in acidic soil, such as pine, beech, willow, oak, dogwood, mountain ash, and magnolias.
|Ash, European mtn.||6-7|
Why Do We Need Ericaceous Compost?
Potting Soil vs. Compost: Know the Differences & Uses
Clemson University. Azalea care. College of Agriculture, Forestry and Life Sciences Azalea Care.
Colorado State University. Currants, Gooseberries, and Jostaberries.
Heather world. A Beginner’s Guide to Growing Heathers
Royal Horticultural Society. on Alkaline soil.
University of Minnesota Extension (2018). Vegetables.
University of Vermont Extension. pH for the garden.
International Camellia Society. Basic camellia care.