Plum Pollination Query

[FB.]

Fruit tends to prefer neutral to slightly acid soil: ph 6.0-7.0.
Some specific varieties will tolerate more extreme conditions.

[northepaul]

Yep would agree to some extent that they like an acidic soil - most of my fruit things seem to thrive here, and potatoes too, and I have acidic clay soil.

[FB.]

It seems to me that the main benefit of clay soil is that the ground holds moisture and nutrients very well. That allows plants to get all the water and nutrients they need to grow strongly.
Inevitably, persistently damp soil will absorb some CO2 from the atmosphere, making the soil slightly acid (just like acid rain).

On the downside, clay soils can often be cold, heavy and prone to waterlogging and flooding, which can literally drown (or rot) plant roots.