Plants That Love High Potash & Elevated pH


The majority of gardeners are aware that the amount of acidity (pH) and balance of nutrients in their soil has a significant influence on the development of their plants, as well as the food harvests and flower blooms that they produce. The use of potash, also known as wood ash, as a kind of fertiliser on tomato plants and other plants has shown to be successful for many gardeners due to the wide range of nutrients it provides as well as the pH correction it provides; nevertheless, this substance is not ideal for every circumstance.

Why Use Potash?

When it comes to nutrients, there are a select number that stand out as particularly important for the development of plants; yet, different plants have different preferences about the quantity of these nutrients that they need. According to The Old Farmer’s Almanac, a balanced pH of 6.5 is just about optimal for the great majority of plants. However, the ideal balance of nutrients and pH for each individual plant is unique to that particular plant. According to the Texas A&M AgriLife Extension, there are main and secondary nutrients that are required for the development of plants respectively.

The use of potash is one way that some of these nutrients may be provided. Potash is an excellent source of primary and secondary nutrients because to the high concentrations of potassium, phosphorus, and carbon that it has, in addition to respectable levels of magnesium and calcium. According to Canpotex, industrial potash is generally derived from a mixture of minerals and chemicals. In addition, it has an increased amount of phosphorus, which is an essential nutrient for the development of roots, flowers, and fruits.

Phosphorus in Soil

Even with an abundance of water and oxygen, phosphorus does not migrate very far from its original location in the soil, since it is not particularly mobile in the first place. As a result of this, you should include phosphorus-fixing plants into the cycle of your crop rotation. In addition, after the growing season is through, you should chip and till the remnants back into the soil so that the nutrient will be more accessible during the next season of growth.

Furthermore, according to Nutrient Stewardship, the levels of soil pH have a significant effect in determining which nutrients are accessible for plant uptake and which ones are not. Phosphates get immobilised in the soil when the pH level drops below 5.5, making them unsuitable for absorption by adjacent plants. Nitrogen, on the other hand, becomes immobilised in the soil when the pH level rises beyond 7.5, making it unavailable for uptake by those plants.

Because of its naturally alkaline composition, wood ash not only contributes phosphorus (and maybe other minerals), but it also makes these elements more absorbable by plants.

Phosphorus-Fixing Plants

It is well knowledge that beans and legumes in general are very skilled at absorbing and storing nitrogen in their roots. However, what about phosphorus? Exist other plants that are capable of removing phosphorus and fixing it? To answer your question, the answer is both yes and no.

A certain kind of fungus is essential for successfully removing phosphorus from rocks and soil. According to research conducted by the University of Maryland, mycorrhizal fungus has a mutually beneficial connection with around 90 percent of the world’s plant species. Incorporating a culture of mycorrhizal fungus on the surface of a tree’s roots may increase the surface area of the roots by 700 to 1,000 times, allowing the tree to extract phosphates from several metres distant from the roots themselves.

Mycorrhizal fungi appear to actually permeate the soil surrounding the roots, dissolve phosphorus from the soil and rock, and then draw it back to the roots, whereas Rhizobium fungi help legume roots fix nitrates by encouraging the roots to form nodules that store nitrates. This process is how the Rhizobium fungi help fix nitrates. Phosphorus is relatively immobile while it is in the soil; but, once it is taken up by plants, it becomes incredibly mobile and moves from the roots to the leaves and then to the fruits as required.

Phosphorus-Loving Plants

Plants that grow well in very high alkaline soil (a pH between 6.5 and 7.5) appreciate phosphorus and flourish in situations that have a high concentration of phosphorus due to the recognised association between high-pH soil and more readily accessible phosphorus.

The website Harvest to Table offers a list of crops that is both comprehensive and useful. The crops are categorised according to whether they like acidic or alkaline soil. Root vegetables, leafy greens, and savoury herbs all flourish and improve their yields when given higher-phosphorus-saturated soil and when they are correctly infected with the Mycorrhizal fungus, according to the findings of GlobalNet Academy, which verifies the inference that these plants need.

Tomatoes like soil with a pH range of 5.5 to 7.5, which is basically the whole range of sustainable pH for plants. This gives them a distinct advantage over other plant species that need a narrower pH range. According to research conducted by the Department of Plant and Soil Science at the University of Vermont, applying wood ash to tomato plants resulted in a harvest that is both more abundant and more tasty.