Is Alkaline Water Good for Plants & Should You Use It?
The pH of your water could be helping – or harming – your plants. Here's what you need to know.
Water is essential for plant growth, but is alkaline water good for plants, or could it be doing more harm than good? If you notice yellow leaves, stunted growth, or plants struggling despite regular watering, your water's pH might be the issue.
Certain plants thrive in alkaline soil conditions, while others struggle to absorb nutrients when pH levels rise. So, how do you know if your plants need alkaline water – or if it’s making things worse? In this guide, we’ll explore the science behind alkaline water, which plants benefit from it, and when it should be avoided. By the end, you’ll have a clear answer on whether alkaline water is the right choice for your garden and how to test your soil to make an informed decision.
How Does Alkaline Water Affect Plants?
What Is Alkaline Water?
Alkaline water has a pH level above 7, making it less acidic than neutral water. It naturally contains dissolved minerals like calcium, magnesium, and bicarbonates. These minerals are key in influencing plant health and soil composition.
Did you know?
Many areas in the UK, particularly those with hard water, already have slightly alkaline tap water. This means some gardeners unknowingly adjust their soil’s pH every time they water their plants. But is this beneficial?
How Soil pH Affects Nutrient Absorption
The pH of soil directly impacts a plant’s ability to absorb nutrients. When soil is too acidic or alkaline, plants have trouble absorbing important minerals. This can cause poor growth, weak roots, and leaf discolouration.
Here’s how alkaline water interacts with soil:
Nutrient Lockout
High pH levels can stop plants from taking in iron, phosphorus, and manganese. This can lead to chlorosis, yellowing leaves, weak roots, and stunted growth.
Reduced Microbial Activity
Healthy soil relies on microbes to break down organic matter and release nutrients. Alkaline conditions slow down microbial processes, limiting nutrient availability.
Soil Hardening & Drainage Issues
Watering often with alkaline water can cause soil to compact. This makes it tougher for roots to take in water and nutrients.
Quick Tip
Before switching to alkaline water, test your soil pH to determine whether adjustments are necessary. For more on this, check out the GOVs take on how to manage soil health.
Which Plants Benefit from Alkaline Water?
Not all plants respond the same way to alkaline conditions. While most prefer neutral to slightly acidic soil, certain species thrive in high-pH environments.
Plants That Prefer Alkaline Conditions
Lavender
Prefers chalky, well-drained soil with a pH of 7-8.
Lilac
Requires alkaline to neutral soil to produce healthy, fragrant blooms.
Clematis
Grows best in slightly alkaline conditions, promoting vigorous root development.
Yew Trees
Naturally found in alkaline-heavy landscapes across the UK.
For these plants, alkaline water will not negatively impact their growth – and may even help maintain ideal soil conditions.
Plants That May Struggle with Alkaline Water
Blueberries
Acidic soil (pH 4.5-5.5) is required for proper nutrient uptake.
Rhododendrons & Azaleas
Often develop iron deficiencies when soil pH becomes too high.
Camellias
Prefer slightly acidic conditions and may struggle if watered with high-pH water.
Alkaline water can lead to yellowing leaves, weak blooms, and slow growth for these plants. The best choice is to use rainwater or filtered water with a balanced pH.
Expert Insight
Acid-loving plants require low-pH soil to absorb nutrients effectively. Watering them with alkaline water can gradually disrupt soil balance, leading to long-term issues.
Sustainable Alkaline Water for Healthier Plants
Many gardeners attempt to adjust their water’s pH using household additives like baking soda or vinegar. However, these methods can be inconsistent and may negatively affect soil health over time.
Using filtered alkaline water is a more sustainable and precise method. It keeps a steady pH balance and avoids unwanted contaminants. This is where the Phox Alkaline Water Refill Pack comes in.
Why Choose Filtered Alkaline Water?
Balanced Mineral Content
The Phox Alkaline Pack keeps calcium levels steady and boosts magnesium. Unlike untreated alkaline water, this helps with hydration for both plants and people.
Removes Unwanted Contaminants
Tap water often contains chlorine, lead, and pesticides, which can disrupt soil microbiology. The Phox filtration process removes these impurities, providing cleaner, purer water for plants.
Sustainable & Locally Made
The Phox refillable system avoids plastic waste. Unlike regular water softeners, it doesn't rely on single-use cartridges. This change helps reduce landfill waste and lower carbon emissions.
Did you know?
Each Phox Alkaline Water Refill Pack lasts for 200 litres (44 gallons) or 45 days. This offers a long-lasting and cost-effective way to hydrate your plants and household with alkaline water.
Should You Use Alkaline Water for Your Plants?
Alkaline water benefits plants that thrive in high-pH environments, such as lavender and lilac. However, it can cause problems with acid-loving plants like blueberries and rhododendrons. It disrupts nutrient absorption, leading to yellowing leaves and poor growth. Test soil pH before using alkaline water to ensure it’s suitable for your plants.
When Alkaline Water Can Be Beneficial
Your soil is too acidic
If a pH test shows excessive soil acidity, alkaline water can help balance pH over time.
You're growing alkaline-tolerant plants
Plants such as lavender, lilac, and clematis grow well at high pH levels, so alkaline water will not harm them.
You want a sustainable alkaline water source
Using a system like the Phox Alkaline Pack gives your plants reliable hydration that's rich in minerals.
When You Should Avoid Alkaline Water
Your plants show signs of nutrient deficiency
Yellowing leaves, slow growth, or weak blooms may mean alkaline water stops proper nutrient uptake.
You haven’t tested your soil pH
Using alkaline water without knowing your starting pH may lead to unnecessary imbalances.
You’re watering acid-loving plants
Blueberries, rhododendrons, and camellias need acidic soil to thrive. Alkaline water can reduce iron availability, weakening plant health.
How to Test and Adjust Water pH for Plants
How to Measure Your Water’s pH
Testing the pH of your water is quick and straightforward, so you can determine whether adjustments are needed.
1. Use a pH Testing Kit
Widely available in garden centres, these provide quick, colour-coded readings.
2. Try a Digital pH Meter
More precise than strips, offering accurate, reusable readings.
3. Check Your Tap Water Report
Many UK water suppliers publish pH levels for local water sources, helping you understand your water’s baseline.
How to Adjust Water pH for Healthier Plants
Lowering pH (for acid-loving plants)
- Add a few drops of vinegar per litre of water.
- Use rainwater instead of tap water for more natural acidity.
- Apply sulphur-based soil amendments for long-term pH balance.
Raising pH (for alkaline-tolerant plants)
- Use filtered alkaline water from a sustainable source, such as the Phox Alkaline Pack.
- Add crushed eggshells to the soil to increase calcium and raise pH naturally.
- Incorporate garden lime for a more permanent pH adjustment.
Quick Tip
Soil pH doesn’t change overnight – regular testing is essential.
The Smart, Sustainable Way to Water Your Plants
Your water’s pH can make all the difference between lush, thriving plants and slow, stunted growth. Some species can adapt to alkaline water, but others cannot. So, it's important to test your soil, know what plants prefer, and pick the right water source.
Why take risks with tap water containing chlorine, pesticides, and heavy metals? With the Phox Alkaline Water Refill Pack, you can give your plants the clean, sustainable water they deserve.
Get the Phox Alkaline Water Refill Pack and make a smarter, greener choice for your plants today.