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Planting distances - ultimate spread or closer?

NollieNollie Posts: 7,529
in Tools and techniques
Contrary to my usual bung ‘em in strategy, I am going to be properly setting out my Hot Border shortly and have been checking planting distances/ultimate spread of each new plant, but different websites state differing ultimate spreads, e.g. 30-75cm for Helenium Waltraut (biggest difference), 30-45cm for Salvia Nemorosa Carradona, Agastaches Black Adder and Tango, 40-60cm for the echinaceas.

I plan to plant in groups of 3 or 5 plants and would like to plant a little closer for more instant effect, but not too close that they get unhealthy and overcrowded too quickly.  

Is there a general rule of thumb or should I just pick the lowest number and plant everything at 30cm apart? Is that too close for any of those plants do you think?

Thanks.

PS I plan to respect ultimate spread for the existing young shrubs and roses in the border to leave a bit of air around them.
Mountainous Northern Catalunya, Spain. Hot summers, cold winters.

Posts

  • BorderlineBorderline Posts: 4,700
    The spread is usually a rough estimate over a 2-3 year period. It also depends on your soil and sometimes aspect and most of all the type of plant. Some plants are slow at establishing, whilst others put on a lot of growth around the base in a year.

    Your original plant/pot size might influence the planting distances and also, how soon you want to see them all knit together naturally. 

    For me, the general middle-of-the-road distance for a 10cm pot size plant would be another 10-15cm all around. This is quite dense, and some might choose for more space.
  • raisingirlraisingirl Posts: 7,093
    A good option is to plant the core perennials of a new bed at their ultimate spread spacing and then 'fill in' with easy annuals like cosmos, cornflowers, euphorbia oblongata and calendula. That gives you an even more instant effect but means you don't have to spend as much time moving and dividing in later years.
    It very much depends what style you're working to. I think 'cottage' works well with the bung 'em in and see what thrives then adjust to suit approach. But if you are 'designing' for a particular form and structure, then working back from where you want to get to is a better method.
    Gardening on the edge of Exmoor, in Devon

    “It's still magic even if you know how it's done.” 
  • Blue OnionBlue Onion Posts: 2,995
    Most of the plants you have selected self seed readily.  Gardening on a budget, I typically plant as raisingirl suggested, with perennials spread wide with temporary annuals between as space fillers.  In a few seasons, you'll have the perennials seeded around and ready to fill in those gaps naturally, creating swaths of repeating color, texture, and levels.  
    Utah, USA.
  • NollieNollie Posts: 7,529
    Thank you all, so to sum up - plant at stated spread or not much less, and be patient - not my strongest point, but I shall endeavour to cultivate it. All excellent points re not having to divide so soon, self-seeding and filling in for temporary bulking up.

    My conundrum with the Heleniums is what spread to choose given advice varies so wildly - would 50cm be a reasonable compromise do you think? Most are Waltraut but I also have a few Moerheim Beauty. I have no idea whether the combination of my improved clay soil, south-facing border and hot summers will inhibit growth or make them grow like crazy...
    Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
  • raisingirlraisingirl Posts: 7,093
    edited April 2018
    Nollie said:
    I have no idea whether the combination of my improved clay soil, south-facing border and hot summers will inhibit growth or make them grow like crazy...
     :) No one is going to be able to answer that one for you - you'll just have to see. I'd probably err on the side of closer spacing, but I'm not very good at gap, so all my gardens end up tending to 'cottage' style and I'm perhaps not being objective there. 

    I'm not sure that you really have to be patient. I think you just need to come up with 2 designs - the perennial one you have. So now design another layout using annuals instead and superimpose that on your perennial plan. You'll get to see that one this year. And you can then design a completely new annual garden for next year, based on what you learn about annuals in your soil this year and how fast your perennials seem to growing in the meantime. Just carry on making a new garden design each year until your perennials have got to where you want them to be.
    Gardening on the edge of Exmoor, in Devon

    “It's still magic even if you know how it's done.” 
  • NollieNollie Posts: 7,529
    :) How true, raisingirl, I am looking for concrete answers, but I guess there’s is no such thing as every garden and growing conditions are different. The ‘plan’ such as it is, is in my head at the moment, so I guess I will just have to go by instinct on the day. I suspect I have over-bought, so things might naturally creep a bit closer...
    Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
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