On Bed Widths and Plant Counts

I have a confession to make. Each season since I started growing cut flowers, the numbers of seedlings and plug plants that I eventually plant out in the field have not matched those stated in the seed sowing schedule and Excel planning sheet. This discrepancy between ‘the plan’ and reality is usually a result of human factors, unpredictable weather, poor germination etc. But most of all — to be completely honest — the discrepancy is a result of bad planning, poor records management and lack of oversight of where the large number seed and cell trays, jumbo plugs, pre-sprouted ranunculus, potted-up dahlias… are to be kept (a space issue) and cared for (a scheduling and planning issue).

This year, I am making changes that are meant to bring more order to my cultivation practices, which I hope will in turn increase the number of stems that I eventually cut for sales. To increase flower production, in other words, by doing less rather than more work. [Book tip: Ben Hartman’s The Lean Farm.]

Recently, while trying to figure out an efficient layout for my new plot in Damhead, I did some studies of the number of plants needed to fill growing beds of different widths. I have been curious about this topic for a while but have never before taken the time to do the proper calculations. There are likely many ways (and better ways) of crunching these numbers. [Book tip: John Jeavon’s How to Grow More Vegetables Than You Ever Thought Possible.] This post simply covers what I tried and what I came up with.

First, what is the conventional or standard bed width? I have understood from talking with friends and colleagues in the Flowers From the Farm network, that cut flower growers across the UK have very different widths and lengths of their growing beds. The layouts of their plots, unsurprisingly perhaps, vary an enormous amount. But with so many options to choose from, what dimensions are productive, and how does one know what layout would be suitable for one’s own site? It was to help me make decisions that I carried out these studies on bed widths and plant counts.

But before I present the comparison, may I enter a caveat: as someone with back issues, I want to strongly emphasise that the width of one’s growing beds ought really to depend on how tall one is. That is, the deciding factor should ideally be the maximum distance (from the path) at which you can comfortably plant, dig, weed, harvest, spray, dead-head, mulch etc. Double that distance and you will have a bed-width dimension that will likely work well for you.

Now to the comparison. What I wanted to find out was how many plants (at a certain spacing) could be grown in a 4m long bed, given a bed width of 0.9, 1.0, 1.1 or 1.2m. For each of these four bed sizes, the diagrams below show planting plans and plant counts for six different plant spacings: 80cm (31.5”), 46cm (18”), 40cm (16”), 30cm (12”), 23cm (9”) and 15cm (6”).

Note: The layouts above assume a flat planting area with no sloping sides. [Reading tip: Bob Flowerdew’s from flat to raised trench beds]

One interesting finding is that the width of bed that one chooses seems to make the most difference (in terms of plant count) when growing plants at a 30cm spacing or less. At 40cm spacing, according to my calculations, you will not fit many more plants in a 1.2m-wide bed than you would in a 0.9m-wide bed. If correct, this implies that the beds one uses for growing certain perennials could, in theory, be several decimeter narrower than those used for annuals. Lots to think about.

This season, all of my growing beds are 1.1 x 4m in size. Because of this dimension, and based on the plant counts above, this year I will grow most of my flowers and fillers in deep 30-cell trays. This will, I think, make sowing, planning and planting easier to manage and keep track of. Below are the key numbers for my plot set-up. (I will save the enigmatic but fascinating topic of succession planning for another journal post =)

In conclusion (and in theory), as long as I know the plant spacing of each variety that I want to grow, the numbers below are what I need to remember. In order to get the correct number of plug plants ready for each bed (with some extras, just in case), I will need to prepare:

  • 40cm (16”) spacing = One 30-cell tray to fill 1 bed.
  • 30cm (12”) spacing: Two 30-cell trays to fill 1 bed.
  • 23cm (9”) spacing: Three 30-cell trays to fill 1 bed.
  • 15cm (6”) spacing: Eight 30-cell trays to fill 1 bed.

This journal post turned out a lot longer than I thought it would. If you have any comments, suggestions or tips then I would very much like to hear from you. Please leave a comment using the form below or simply send me an email at moa[at]rootandbranchflowers.co.uk

Have a lovely weekend and stay safe.

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6 thoughts on “On Bed Widths and Plant Counts

  1. Fantastic so simply explained something I struggle with as a dyslexic !

    1. Thanks very much Sarah for your kind comment. I am so pleased that you found it useful. I bet you have experimented a huge amount with how to plant, grow and care for those beautiful peonies that you produce. I always need to visualise these things on paper, in order to fully understand what the numbers are showing.

      1. I have a very simple system with our peonies after inheriting a very weedy field with plants haphazardly planted making mowing and cultivating a nightmare.We use planting membrane as a wedding suppressant and plant them a meter apart. Weeding is still difficult and time consuming
        as we are on the edge of an open unfenced field but we keep the grass between the rows mowed weekly.
        It is my cutting garden where I have meter wide bed, I am 5ft 1in so narrow but could never work out how many plants to grow SO thank you
        Do you mind if I copy this Moa?

        1. Yes sure Sarah, go right ahead and use it. All the best.

  2. I’ve just come across this via a search in the FFTF FB group as still trying to finalise my plans, it is so helpful and clear to understand, thank you for spending your time to share 🙂

    1. Oh it is my pleasure, I am glad it is useful to you. Thanks for reading and for your lovely comment!

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