Soil Calculation for Planters - seems too much?

Discussion in 'NEW Gardeners !' started by portoman, Nov 9, 2021.

  1. portoman

    portoman Apprentice Gardener

    Joined:
    Apr 27, 2021
    Messages:
    12
    Gender:
    Female
    Ratings:
    +2
    Hi

    I've got 2 new planters, and each has dimensions of 121 cm long, 51 cm wide, and 21 cm deep. Using an online calculator, it said I need 119 litres per planter. Another calculator said I needed 25kg per planter. A third one said 130 litres per planter

    I'm pretty confused..........
     
  2. Upsydaisy

    Upsydaisy Total Gardener

    Joined:
    Apr 26, 2017
    Messages:
    17,442
    Gender:
    Female
    Occupation:
    Living in hope of world wide peace.
    Location:
    Hampshire. Zone 8b
    Ratings:
    +54,365
    Hi, sorry I can't help you as I don't calculate it, just fill pots and containers until I'm happy with how they look.
     
    • Agree Agree x 2
    • Palustris

      Palustris Total Gardener

      Joined:
      Oct 23, 2005
      Messages:
      3,572
      Gender:
      Male
      Occupation:
      Retired
      Location:
      West Midlands
      Ratings:
      +2,967
      I worked it out as 130 litres which would fill one to the top so a bit less would be needed.
      Some sellers use Litres, others use kilograms. Easier I think to work in volume rather than mass.
       
      • Like Like x 2
      • Agree Agree x 2
      • Informative Informative x 1
        Last edited: Nov 9, 2021
      • pete

        pete Growing a bit of this and a bit of that....

        Joined:
        Jan 9, 2005
        Messages:
        47,723
        Gender:
        Male
        Occupation:
        Retired
        Location:
        Mid Kent
        Ratings:
        +84,381
        I think it would be best to buy a couple of bags and see how far it goes.
        It's not going to be any exact science because compost needs to be open and broken down when you take it out the bag, kind of fluffed up, if you get my meaning.
        It then gets packed down over time. :smile:
         
        • Agree Agree x 2
        • gks

          gks Total Gardener

          Joined:
          Feb 28, 2021
          Messages:
          1,509
          Gender:
          Male
          Occupation:
          Production Manager
          Location:
          Cumbria
          Ratings:
          +4,433
          The third one is correct, but as pointed out, that amount would fill the planter to the rim.
           
          • Informative Informative x 1
          • misterQ

            misterQ Super Gardener

            Joined:
            Aug 25, 2015
            Messages:
            749
            Gender:
            Male
            Location:
            Stamford Hill, London N16 6RU
            Ratings:
            +1,770
            I have to do these types of calculations every year since we use a lot of containers in our community garden.

            1 cubic meter = 1000 litres

            Converting the measurements into meters:

            L = 1.21m, W = 0.51m, D = 0.21m

            Volume of compost required:

            V = L x W x D

            V = 1.21 x 0.51 x 0.21 = 0.129591 cubic meters

            V = 0.129591 x 1000 = 129.591 Litres


            I know that B&Q's Verve 125L Multi-purpose compost weighs somewhere between 45-49kg depending on moisture content.

            Lets assume 45kg per 125L bag.

            That's 45/125 = 0.36kg per Litre

            So, 129.591L would weigh 129.591 x 0.36 = 46.65276kg


            The thing about compost is that it will get compressed and the level will drop noticibly over time so it is always better to buy atleast a third more than you actually need:

            129.591/3 = 43.197L


            But, don't overlook the potential free compost at this time of the year: I am talking about fallen leaves and autumn prunings from clearing the garden. Collect them all up and make your own compost.
             
          • Jack Sparrow

            Jack Sparrow Total Gardener

            Joined:
            Jul 24, 2017
            Messages:
            2,604
            Gender:
            Male
            Location:
            Peterborough
            Ratings:
            +5,414
            The B&Q 125l bag of multipurpose compost is extremely heavy.

            G.
             
          Loading...

          Share This Page

          1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
            By continuing to use this site, you are consenting to our use of cookies.
            Dismiss Notice