T: 01246 260874
F: 01246 455244
W: www.chesterfieldhydroponics.co.uk
E: [email protected]
PH – What it is and how to control it
PH is basically a measure of the acidity or alkalinity level of a substance. It’s a term used in
chemistry to measure the activity of hydrogen (hydroxyl and hydroxide) ions in an aqueous
solution. The concept of PH was primarily introduced to science in 1909 and shortly afterwards
revised and developed into the modern definition and measurements that are used today. Whilst it
is agreed that the “H” in PH represents hydrogen, it is debated whether the “P” stands for power
or potential. Either way, the power of hydrogen or the potential of hydrogen both help clarify the
abstract definitions often associated with the mysterious symbol.
The PH Scale
The PH scale is a tool used to determine the PH level of a given substance. The PH scale ranges
from 0 to 14, with 0 being the most acidic, 14 the most alkaline and 7 the neutral midpoint. The
PH scale is logarithmic, meaning that each value above or below neutral represents a tenfold
increase in acidity or alkalinity from the previous unit. For example, a PH level of 4 is ten times
more acidic than 5 and a hundred times more acidic than 6. On the other end of the scale, a ph
level of 9 is ten times more alkaline (or basic) than 8. This makes it crucial to take accurate
readings when testing PH levels of a nutrient solution.
Why Is PH Important For Plants
PH affects just about everything and plants are no exception. PH levels affect many factors in a
plants life cycle. That’s why it’s important to consider the PH level of the soil or medium plants are
being grown in, as well as the solution they are being watered with.
Certain Plants Grow Better In Acidic Or Alkaline Environments
Just like animals, different plants have different food preferences. Plants such as citrus fruit,
blueberries, blackberries, strawberries, potatoes and orchids are prime examples of acid loving
plants. Plums, poppies, sage, cherries and sunflowers are plants that prefer a more alkaline
environment. Many plants are tolerant of a wider range of acidity and alkalinity, including beans,
broccoli, garlic, peas, melons, onions and corn – to name a few.
pH Values For Different Hydroponic Crops
Plant
pH Range
Beans
Broccoli
Cabbage
Cantaloupe
Carrots
Chives
Cucumbers
Garlic
Lettuce
Onions
Peas
Pineapple
Pumpkin
Radish
Strawberries
Tomatoes
6.0-6.5
6.0-6.5
6.5-7.5
6.5-6.8
5.8-6.4
6.0-6.5
5.8-6.0
6.0-6.5
6.0-6.5
6.5-7.0
6.0-6.8
5.0-5.5
5.0-6.5
6.0-7.0
5.5-6.5
5.5-6.5
Chesterfield Hydroponics is part of Recon Electrical Wholesale Ltd
Units 1-6 Ambrose Buildings, Broombank Road, Sheepbridge, Chesterfield, Derbyshire, S41 9QJ
VAT Reg: 598 6371
Company Reg: 3191383
T: 01246 260874
F: 01246 455244
W: www.chesterfieldhydroponics.co.uk
E: [email protected]
Availability Of Nutrients
Plants rely on a specific group of macro and micro nutrients to provide the bulk of their
sustenance. Without proper nutrition, plants experience deficiencies and perform under par.
Mineral nutrients are only soluble within a solution when the PH level is balanced within a prime
range (usually around 5.5 to 6.2). Macronutrients tend to be less available in soil with low PH,
whereas micronutrients are less available in high PH soil. If soil levels stray from the ideal range,
vital nutrients will be rendered unavailable to the plant and the plant will be unable to eat the food
it needs.
Availability Of Nutrients Available At Different pH Levels
NOTE:
This chart is for soilless (hydroponic) gardening only and
does not apply to organic or dirt gardening.
Disease Cure & Prevention
Certain diseases thrive in environments that are too acidic or too alkaline. For example, powdery
mildew (a common garden nightmare) thrives on the surfaces of leaves with a slightly acidic PH.
By treating the plants with a foliar application with a high PH (around 8), it will kill the mildew
spores and help prevent re-occurrence of the disease.
What Is The Optimal PH Range For Plants Grown In Soil
While different plants have varying ranges of PH to achieve optimal growth, most plants cultivated
in soil will perform best when grown in a PH range of 6 to 6.5. When growing in soil, the grower
will ideally test the soil and the solution used to water the plants. If the soil is homemade, there
are test kits available to test the PH of the soil. Most commercial grade speciality soils that come
pre-bagged have already been tested and PH balanced. The water is what differs from region to
region and must be carefully monitored on a regular basis. The PH of the nutrient feed solution
should be checked after adding fertiliser and adjusted to reach the optimal range of 6 to 6.5. PH
adjusters designed for horticultural applications are available at our hydroponics counter.
Chesterfield Hydroponics is part of Recon Electrical Wholesale Ltd
Units 1-6 Ambrose Buildings, Broombank Road, Sheepbridge, Chesterfield, Derbyshire, S41 9QJ
VAT Reg: 598 6371
Company Reg: 3191383
T: 01246 260874
F: 01246 455244
W: www.chesterfieldhydroponics.co.uk
E: [email protected]
What Is The Optimal PH Range For Hydroponically Grown Plants
As with soil, plants grown hydroponically have PH preferences depending on plant variety. In
general, plants in hydro tend to do better in a slightly more acidic environment than plants in soil.
A PH range of about 5.5 to 6 is ideal for most hydroponic growth. It is particularly important to
consider PH in hydro, as all of the plant nutrition is coming from fertiliser solution. Too high or too
low of a PH level will prevent either micro or macro nutrients from being absorbed by the plants.
When growing with hydro, the medium used – whether it is inert or not – will have an effect on PH
levels.
Why Does The PH Of A Nutrient Solution Fluctuate
Plants use different elements, such as nitrogen, at different rates. As plants eat, they deplete
certain substances and tend to raise the PH as they digest the fertiliser in the solution.
How Is PH Tested For Horticultural Purposes
Paper Test Strips – These are among the most inexpensive and simple methods of testing PH.
Paper strips infused with PH sensitive dye are dipped into the nutrient solution being tested. The
colour that appears on the strip corresponds with a colour chart to determine PH level.
Liquid Indicator Solutions – Similar to the paper test strips in that they use colour, the liquid
indicator solution is a popular and reliable method for novice or budget growers. A small sample
of nutrient solution is taken from the reservoir in a container provided in the test kit. A few drops of
PH sensitive liquid are added to the solution and change to specific colours depending on the PH
level. The colours correspond with a chart that determines the PH.
Digital Meters – Accurate and easy to use, digital meters are the most logical choice for
professional growers. They use a glass bulb electrode to precisely determine the PH of the
solution being tested. Digital meters must be stored properly and calibrated often. They are
notorious for breaking down and can be a source of frustration for growers who rely upon their
precision. When using digital meters, it is important to keep them clean and wet while storing
them. It is also a good idea to have al liquid test kit on hand – just as a backup.
How Is PH Adjusted For Horticultural Purposes
Many common household items will have an effect on the PH level of pure water. Some of these
include lemon juice to lower the PH or baking soda to raise it. However, for the serious grower, it
is recommended to use PH adjusters that are specifically designed to work well within a
hydroponic nutrient solution. PH down (acid) lowers PH levels, while PH up (base) raises them.
There are several brands of PH up and down available in the hydro industry. Choose brands that
do not add dyes to their PH adjusters, as artificial dyes have no added benefit to the health of
plants. Look for adjusters that contain at least two or three acids in the PH down and two or three
bases in the PH up. This will provide for a more stable PH level with less drastic Fluctuation.
There are many important factors to consider when growing; and PH ranks high in importance
amongst them. Understanding why PH is important and how to manage PH balance helps ensure
happy plants. Attention to detail in the garden provides for a much more deserved and rewarding
result in the end – treat your crops right and enjoy the bounty of healthy harvests.
For further information contact one of our experienced team on 01246 260874 or email
[email protected].
Chesterfield Hydroponics – We Know How To Grow…
Chesterfield Hydroponics is part of Recon Electrical Wholesale Ltd
Units 1-6 Ambrose Buildings, Broombank Road, Sheepbridge, Chesterfield, Derbyshire, S41 9QJ
VAT Reg: 598 6371
Company Reg: 3191383