If camelias and acers grow well in a clay soil but rhododendrons and cytisus don't, does this mean the soil is only slightly acidic or a bit more than that?
My soil is slightly acidic clay according to this website. Lots of camellias, acers and rhododendrons around here, but don't see many cistus round there parts.
Knowledge is knowing that a tomato is a fruit. Wisdom is not putting it in a fruit salad.
I don't know. My experience is that some plants are acid lovers and some are lime haters and plant labels tend not to distinguish between those. I've not grown cytisus successfully (although saying that, actually I've a white one that's looking amazing this year - first time it's bloomed), but do grow azaleas, rhodos, camelias and acers on my acidic clay. The azaleas and rhodos need quite free drainage. So a guess would be that they are more fussy about wet feet than they are about soil pH. They are woodland plants that seem happiest in leaf litter - i.e. very loose and tending to be dry. The camelia seems to need more fertility in the soil. But that's observation not knowledge so could be just the fluke of my garden conditions
“Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first”
Generally speaking,clay soil's are not necessarily more acidic than sandy or loamy soil. What defines the soil's texture, not its acidic or alkaline pH level. However, clay soil acts acidic in a number of ways even when it is not actually acidic, and there are some cases where the two properties are connected.
Now the boring science bit
The power of hydrogen, or pH, measures whether a liquid is an acid or a base by determining how many hydrogen atoms it has. Substances with lots of hydrogen, such as battery acid, vinegar or lemon juice, are very acidic and have low pH numbers, from about 6 to 1. Substances with fewer hydrogen ions, such as baking soda or bleach, are more basic, or alkaline, and measure from about 8 to 15 on the scale. Water is neutral and has a pH of 7.
Clay soil has tiny particles of dirt that hold together when they're damp, forming a firm ball when you squeeze the damp earth in your hand. The dense nature of the soil holds both water and nutrients in it for longer periods of time than sandy soil, where nutrients and water flow through the soil quickly. As a result of the water runoff, plants in clay soil have more chances to absorb both water and nutrients than plants growing in sandy soil.
Soil scientists measure minerals in the soil, which are both acidic and basic, using a cation exchange capacity number, or CEC number. The number measures the capacity of the soil for holding minerals by looking at the electric charge of the minerals' molecules and atoms.
The relationship between clay soil and CEC suggests that clay soil is acidic. That my be the case typically in some areas, but it's not always true.
Clay soil has a higher CEC count than sandy soil, meaning that it has more capacity to hold hydrogen ions, but not that it necessarily holds enough hydrogen ions to make it consistently acidic.
Clay soil requires fewer chemicals to lower the pH than sandy soil does, making it appear more acidic. But the amount of additives has more to do with the chemicals running through the soil than it does the pH of the soil to begin with.
Areas with lots of rainfall frequently have acidic soil, sometimes due to acid rain, and they also tend to have clay soil. But although these are typical features, the texture and pH don't necessarily have a cause-and-effect relationship.
"You don't stop gardening because you get old, you get old because you stop gardening." - The Hampshire Hog
Thanks @Pete.8 slightly acid but base rich. I'll have to find out what base rich means😊 I was amazed to see that it even has a street map superimposed! A few streets away, the soil is totally different apparently.
Thanks for observations @raisingirl. I wish they would say on labels too. You have to be particularly careful if you spot something unusual outside your area.
@Hampshire_Hog my clay soil is acidic. I've tested it. pH 5.5, generally. I can grow blueberries in open ground. I've got my veg beds up to neutral after 5 years of manuring. There is limestone in the geology here but it's extremely hard (famously so) and therefore the soil seems to be lime free. According to my book, areas of high rainfall tend to have acidic soils if that soil has not been regularly fertilised/manured. I used to live near Bristol. That had even heavier clay soil and was high pH. I assume because it's on the Cotswolds, with very soft limestone underlying, tending to make both the soil and the ground water more limey
“Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first”
Looking at that site @Pete.8 it confirms what I thought. Shallow loam, lime rich over lime base, free draining, in my area, with areas of heavy clay, more pockets than areas, but still not sure about ph.
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Lots of camellias, acers and rhododendrons around here, but don't see many cistus round there parts.
Wisdom is not putting it in a fruit salad.
But that's observation not knowledge so could be just the fluke of my garden conditions
Generally speaking,clay soil's are not necessarily more acidic than sandy or loamy soil. What defines the soil's texture, not its acidic or alkaline pH level. However, clay soil acts acidic in a number of ways even when it is not actually acidic, and there are some cases where the two properties are connected.
Now the boring science bit
The power of hydrogen, or pH, measures whether a liquid is an acid or a base by determining how many hydrogen atoms it has. Substances with lots of hydrogen, such as battery acid, vinegar or lemon juice, are very acidic and have low pH numbers, from about 6 to 1. Substances with fewer hydrogen ions, such as baking soda or bleach, are more basic, or alkaline, and measure from about 8 to 15 on the scale. Water is neutral and has a pH of 7.
Clay soil has tiny particles of dirt that hold together when they're damp, forming a firm ball when you squeeze the damp earth in your hand. The dense nature of the soil holds both water and nutrients in it for longer periods of time than sandy soil, where nutrients and water flow through the soil quickly. As a result of the water runoff, plants in clay soil have more chances to absorb both water and nutrients than plants growing in sandy soil.
Soil scientists measure minerals in the soil, which are both acidic and basic, using a cation exchange capacity number, or CEC number. The number measures the capacity of the soil for holding minerals by looking at the electric charge of the minerals' molecules and atoms.
The relationship between clay soil and CEC suggests that clay soil is acidic. That my be the case typically in some areas, but it's not always true.
"You don't stop gardening because you get old, you get old because you stop gardening." - The Hampshire Hog
I was amazed to see that it even has a street map superimposed! A few streets away, the soil is totally different apparently.
I've got my veg beds up to neutral after 5 years of manuring. There is limestone in the geology here but it's extremely hard (famously so) and therefore the soil seems to be lime free.
According to my book, areas of high rainfall tend to have acidic soils if that soil has not been regularly fertilised/manured.
I used to live near Bristol. That had even heavier clay soil and was high pH. I assume because it's on the Cotswolds, with very soft limestone underlying, tending to make both the soil and the ground water more limey
Wisdom is not putting it in a fruit salad.