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Advertised 'height and spread'

Dirty HarryDirty Harry Posts: 993
Does anyone know of any sites that accurately list these figures for plants?

I'm making a new border this year so trying to plan what goes where but the inaccuracy of a lot of these doesn't make it easy.

A quick example would be the erysimum Bowles' Mauve I have-

Height and spread listed as 45cm x 50cm. The actual plant I have is more like 1.2m x 1.2m.


  • B3B3 Posts: 21,486
    A lot depends on your growing conditions
    In London. Keen but lazy.
  • Dirty HarryDirty Harry Posts: 993
    Yes I'd figured that would play a part but I'd have still hoped for things to be in a rough ballpark rather than potentially so far out.

    Is the best way to plan a border to ensure enough room is given then re-assess after a year or two?
  • edhelkaedhelka GwyneddPosts: 2,113
    I usually check a couple of websites to see the range of sizes or the average. It can't be precise because the same plant can grow very differently for different people.
  • amancalledgeorgeamancalledgeorge South LondonPosts: 2,302
    I think the RHS website is quite accurate but measurements are not a patch to actually having some growing experience in situ. For the ubiquitous Bowles Mauve you mentioned they go with a 0.5 to 1m in height and spread which is a fair representation of the plant, depending on its cultivation conditions. Any site that pretended to be more accurate it would probably be just a guess and I wouldn't trust it. 
    To Plant a Garden is to Believe in Tomorrow
  • Dirty HarryDirty Harry Posts: 993
    Mmm if you've found the RHS site to be generally accurate I might use that as my guide and go by the larger numbers.
  • LG_LG_ gardens in SE LondonPosts: 3,798
    edited June 2020
    I would go with the RHS site too. 
    Two things to note - as well as the eventual height and spread range in the box, they also often give species / cultivar specific height in the description box (eg: Also note the 'time to ultimate height' - if it's several years then you probably don't want to leave all that space bare for ages, but instead go for shorter-lived plants nearby while it grows and / or plan to remove or rethink things as time goes on. 
    'If you have a garden and a library, you have everything you need.'
    - Cicero
  • Dirty HarryDirty Harry Posts: 993
    Yes good shout, foxgloves can come into their own then as well as gap fillers.
  • fidgetbonesfidgetbones Posts: 15,864
    Planning a new border, I put the plants in that are going to fill it at the required spacing, then fill the gaps in between with short lived plants. I used buddlejas and lavatera to fill a shrub border alternating between the slower growing, more expensive, longer lived ones. As the  magnolias etc got bigger, I took out the lavateras and buddlejas.  In a herbaceous border, in shade use foxgloves to fill gaps, in sun use cosmos and nicotiana.
    You don't stop doing new things because you get old, you get old because you stop doing new things. <3
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