Through LJN Chat last night, we threw up the question about Tree and Plant specification, and who knew what. It transpired that no LJN Member on Chat last night knew how to specify a Tree for a project or to buy, so here goes.
Trees - are sold commercially by their girth and not height. The girth is measured 1 metre above gound level, and is the circumference of the trunk in centimetres.
The scale of Tree sizes is this:
4-6cm (normally a typical Garden Centre Tree)
6-8cm, 8-10cm, 10-12cm, 12-14cm, 14-16cm, 16-18cm and 18-20cm
Beyond that the scale is in 5cm breaks 20-25cm and so on.
The exception to the rule is Olea europaea (olive) where the girth is measured at ground level.
Some Trees can make exceptional growth when young. An example is Betula, that as a 6-8cm Tree in a 15 litre can attain 250cm in height, but is still a 6-8cm Tree. An Acer pseudoplatanus Brilliantissimum on the other hand is slower growing and may only attain 180cm as a 6-8 Tree in a 15 litre.
So girth tells us the age of a Tree, and not the height. So the age of the Tree sets the price.
Multi-stemmed Trees - for Trees such as these, like Betula Jacquemontii these are sold by height. 250-300cm for example.
Shrubs - Irrelevant of pot sizes, rootballed, bare root, most Shrubs above the bog standard 2-3 litre size are sold by height.
The scale is as follows:
From the 10cm to 100cm the scale is by 10cm, i.e 50-60cm
Beyond that the scale increases to 25cm.
Conifers - are usually the same size specification as Shrubs.
We hope this is of use to LJN Members, and any questions please ask.
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Replies
The national plant spec doesn't have a 4-6cm category - usually trees below this size are sold by height alone - the 2 categories below 6-8 cms are : 175/200 cms, and 200/250cms.
Rather bizarrely, the tree girth measured in centimetres often gives a good estimate of the trees height in feet - so an 8-10 cms tree can be expected to be 8 - 10 feet tall! BUT this is a rough guide - as Steve says, there are significant variations between species.
If anyone wants a copy of the table showing girths, heights, and clear trunk heights (trunk height before the canopy starts) you can pm me.
Nick Steele said:
Agree Nick 4-6cm can be a very vague specification, normally relating to Trees sold in GC's, 7.5 -15 litre.
NEXT - Standards and ½ standards :-))))
Nick Steele said:
For a "Specimen Plant" we would define, having sold them for the last 16 years as being a minimum
Tree 14-16cm girth Tree
Shrub 125/150cm minimum 35 litre
Gaynor Witchard said:
Very good Nick, but takes no account of things like Olea europaea ½ standard, Quercus Ilex or most evergreen Trees. Good for deciduous ones though.
Does not go beyond 14-16 why?
Nick Steele said:
Yes I think it is primarily intended for standard form deciduous trees. You do see Holm Oak spec'd using this system in the trade, but clearly olives and most evergreens just aren't the right form to fit the spec.
I think it does go beyond size 14-16, but we don't, because few of our customers want trees larger than that, and they start to exceed our handling abilities beyond those sizes (although we delivered a 160 litre 20-22 cms Betula jacquemontii last week - took 3 of us mind!).
very good but many customers requirements usually decided by height & price.
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