Soil grain / type

[Ollie]

Newb question:

Some species have quite thin spindly feeder roots (e.g. a lot of conifers), others have relatively fat feeders (e.g. ficus).

Does the size (diameter) of the feeder root influence the soil type / particle size used?

 

[Pitoon]

Coarser substrate will create thicker roots, while finer substrate will produce finer roots.

All depends on what you are trying to achieve.

 

[MrWunderful]

Yes, but kind of the opposite. The substrate type has an effect on how the roots inside it are developed.

 

[Kanorin]

Yes, but kind of the opposite. The substrate type has an effect on how the roots inside it are developed.

Yup.

But, I think the primary thing most people are thinking about when they choose a given substrate (aside from cost and availability) has to do with keeping the roots (and tree) healthy by achieving a wet-dry cycle that lines up with your watering schedule.

Species, climate, substrate type, amount of foliage, and pot size and shape - all effect how quickly the soil will dry.

Different species like things a little bit drier or wetter, but in general the top 1-3cm or so of substrate partially dries out between waterings. Many people have written more in-depth descriptions of how to judge this.

 

[sorce]

The soil effects the root growth in such a way, that it reflects tree health. Top growth, is then what determines how the roots grow into said soil.

This entire cycle should be considered.

Sorce

 

[Bnana]

But it also works the other way around, trees have a preference for different soil types. That's more an issue if you want to understand where they naturally grow.
Willows and poplars can survive flooding and some grow well in heavy clay, other species, such as junipers, need well drained soils but can stand drought. A common juniper wouldn't grow where a willow thrives.
That's partly moisture but also soil type.