planting pit soil

[Dean O]

any recommendations for backfill for a planting pit?

 

surrounding ground is post development, slaked clayey, gloopy and anaerobic so drainage etc has been thought of.

 

theres no need for the soil to be structural as its a back garden location (rather than street tree)

 

is there anyone who can supply a sandy loamy compost soil off the shelf.

quantity required will be approx. 3 cubic metres. I didn't want to mix my own if I could help it.

 

I looked at Melcourt topsoil but the pH seems a little high to me - at up to 8.2?

 

thanks

Dean

[penfold]

Greentech do a specialised tree soil; can't remember the name of it but have a look on their website.

[jaime bray]

I would be looking to address the soil and species relationship. How bad is the soil really? Would it support trees per se. If so then I would make sure that the tree species is compatible with the soil present.

 

If you reinstate the planting pit soil with high quality soil there is a tendency for the roots to stay in the planting pit. Consequently, when the tree begins to put on shoot growth in years to come there is a possibility, not certainty, that the roots will not be sufficient for secure anchorage of the crown portion above soil level, resulting in root plate failure.

 

If we have a nice warm bed in the winter, we are less inclined to get out of it. The same does apply to tree roots. I am a frim believer in treat them mean and keep them keen.

 

The ideal is to encourage roots to exit the planting pit into the surrounding soil, by providing Versace soil in the pit it will take longer for the roots to exploit the surrounding soil, and they may sit in the pit exploiting the ream soil, to the detriment in years to come.

 

Barchams are already preparing trees for hardship of urban environment with similar practices and their street ready tree stock... I think. or they were last time I visited them.

[Dean O]

thanks for the replies, I will look into greentech

 

Jamie - thanks yes this has been considered, and normally I would agree, but in this situation, unfortunately, beyond the incorporation of suitable drainage (a la BS8545) and replacement soil (as the existing is, to use a technical term: sh*t) wider soil amelioration is not possible.

 

the tree will be maintained at a relatively small size and so planting pit volume, and the use of a subterranean anchoring system seems to be the most suitable way of compensating for the factors you describe.

[Dean O]

Greentech's soil seems more suitable on the pH front - but is 'structural' - will/does this have any bearing?

[treeseer]

In the course of improving drainage, soil outside the pit can be amended. the idea is to avoid interfaces; break up the clay as much as possible.

What species is going in?

[Ruskins Trees]

Beware planting anything in a heavy soil.

 

The rootball will inevitably be a lighter soil. Moisture will wick across from the heavy soil to a light soil. The planting pit/rootball will fill up like a sink, drowning the plant.

 

We had a client who will not be told, he had a digger, so each year he buys a couple of trees from us, digs a pit bigger than the previous year "as I have clay soil (& therefore thinks he needs to backfill with lighter compost/soil) ", plants them, the pits then filled up with water and drowned the trees. Took him three years to believe us.

 

Been reading recent literature all of which promote no more than 5% compost, spoil as vast majority of backfill and get Mycorrhizal/Microbes from soil around healthy plants on site by adding this to the backfill.

 

If you cannot drain the soil, mound plant or right tree, right place.

[treeseer]

I'm in a warmer climate and 50% compost/amendment by volume is not unusual. 50% is standard in Singapore for instance. It's all about blending, wide and deep. Good advice to get Mycorrhizal/Microbes from soil around healthy plants same species and adding this to the backfill.

 

Getting soil to drain is key; i use a 5' iron rod for starters.