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Choosing the right compost for two very large wooden planters?

After finally getting the right person to finish my two very large planters and line them, I am eager to crack on and get some spring bulbs in and then next summer, plant a Bee and Butterfly friendly border into the planters, but before I start im keen not to make a mistake on my choice of compost when I comes to a smaller pot I usually just use my preferred choice of compost being Miracle Grow with water retention, it's serviced me well in the past, but when it comes to a much larger container where I don't want to be changing the compost that often but instead just adding nutrients to it as you would a border in a garden, which mixture of compost what would you suggest to use as and around good idea and what you add part grit to it to help with drainage. Any advice would be kindly welcome 

Posts

  • K67K67 Posts: 2,506
    John Innes 3 is best mixed with some multi purpose compost, ericacous if plants need that type of soil. You can use John Innes 2 instead as it's basically the same mix.
    I always add some garden soil as it's got 'life' in it.
    You can add composted bark, extra grit, bagged top soil and a bit of bagged manure or home made compost, depending on what you intend to plant.

  • Apols if this is out of turn, but how does the drainage work on those?
    “Rivers know this ... we will get there in the end.”
  • FairygirlFairygirl Posts: 55,117
    Yes - have you put holes in the bottom of these? You'll need lots, and in the plastic too, before you add anything. It may cause a problem with staining, if they're staying on the decking too, so you may need to move them now and again for cleaning underneath.

    Soil mainly for the planters, with added compost/grit etc according to what you're growing, as @K67 says. Bulbs won't mind so much, generally speaking, but compost alone is no use for anything other than annual planting.  :)
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • SydRoySydRoy Posts: 167
    Nice planters!
    Decide what you're going to put in them first. Lavender or herbs for example wont thank you for a rich moisture retentive compost mix.
    The position is important too. It appears there is a planter under a large tree.
  • Thank you guys loads of great advice, so to answer a couple of your questions, firstly drainage the bottoms of the planters are made up of 4×2 planks with spaces in between so excess water can escape there is a membrane lining the planter which lets the water out but keeps the soil in. As for @SydRoy question of the planter under the tree it will eventually be moved over onto the gravel on the right-hand side, once I have taken a trip to the local recycling Centre with the pile branches that is lying there at the moment off the said tree I've just had trimmed.
    Also to answer the question of what do I instead to plant in them, well initially spring bulbs but after they have finished im planning on growing alot of the pants from seed to save on a bit of money but for the like of the lupins and foxgloves I will probably buy those as I want flowers the same year, so it's going to be a cottage garden-inspired theme but also with butterfly and bee-friendly spices, I don't think im planning of any that will need specialised soil i.e. Ericaceous soil, some of the plants may like the soil more free draining than others and with a grit soil mixture but I should imaging it's always good to have a part grit mix anyway in most cases, I hope this answers most of your questions 🤔👍
  • FairygirlFairygirl Posts: 55,117
    A decent, free draining mix will support most plants, and you can then tailor it if necessary.  :)
    Another thing you can do with long planters is to put extra 'dividers' in along the length to give you more options - drier areas, different soil types etc. 
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
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