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Growing lavender in used compost - a disaster waiting to happen?

celcius_kkwcelcius_kkw Posts: 753
in Plants
I’ve got a large pot of used compost from this year’s sweet peas which I have now removed. I have a small pot of lavender which needs to go into a larger container so I wonder if I could just transfer the plant directly into that large container of used compost? I read that lavender likes poor soil after all? 

I garden on a balcony so there’s nowhere for the used compost to go but into the bin if I can’t reuse it for other plants... 
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Posts

  • BorderlineBorderline Posts: 4,700
    As long as the compost is either loam-based or loam-based part mixed with a bit of multi-purpose compost. If it is just multi-purpose compost, I would not use it.
  • InglezinhoInglezinho Posts: 568
    Mediterranean plant. Sun,.dry soil, no fertilizer. English lavender: Lavanda angustifolia, does better in damp conditions.
    Everyone likes butterflies. Nobody likes caterpillars.
  • celcius_kkwcelcius_kkw Posts: 753
    @Borderline What’s the purpose of loam soil? I think this one is pure MPC, but I could always add some fresh compost to top it up? 

    @Inglezinho - mine is English lavender.. I take it poor soil means nutrient deficient soil? Therefore used compost surely would be ideal as it will be pretty devoid of any nutrients..? 

    The other thing is that the sweet pea roots are still trapped within the compost.. should I just try to loosen them with a hand rake? 
  • edhelkaedhelka Posts: 2,351
    I use used compost mixed with garden soil and grit for lavender and similar plants. In your balcony situation, where disposing of the used compost isn't easy, I would go for it. Just make sure it drains well.
  • DovefromaboveDovefromabove Posts: 88,147
    edited August 2020
    Inglezinho said:
    Mediterranean plant. Sun,.dry soil, no fertilizer. English lavender: Lavanda angustifolia, does better in damp conditions.
    Confused by that suggestion  🤷‍♀️ given that Lavandula angustifolia is native to S France, Spain and the Pyrenees it definitely does not ‘do better’ in damp conditions.

    It may be called ‘English lavender’ but it is not an English native ... it needs very free-draining gritty soil ... providing it gets that it can cope with English weather, but it is not happy in damp claggy soil. 


     

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • Joyce GoldenlilyJoyce Goldenlily Posts: 2,933
    I would dig out the sweet pea roots, give the compost a good digging over the loosen it up and then plant the lavender. If you can add a couple of handfuls of grit or sand to the pot it would help but it is difficult to buy small quantities, I give my lavender bushes a dusting of lime around the roots each year to keep them growing. Cut them back to just above green growth when the flowers have finished, {councel of perfection.Do as I say, not as I do.] I am a sucker for leaving mine until the bees stop visiting them they love lavender so much. 
  • celcius_kkwcelcius_kkw Posts: 753
    @edhelka @Dovefromabove @Joyce Goldenlily

    Thanks all.. I have plenty of perlite and grit actually so drainage shouldn’t be too much of a challenge. The bottom part of the compost is sort of clumpy because of the roots but they’re quite fine so I should be able to loosen them up before I plant my lavender in it. I did wonder if I should mix in some slow release fertiliser to improve the nutrient content..? Or is that not necessary? 


  • Joyce GoldenlilyJoyce Goldenlily Posts: 2,933
    No. Lavender does not need much in the way of nutrients. Wait until your lavender is gowing well and then give it a very light feed of the slow release fertilizer, next year.
  • LoxleyLoxley Posts: 5,698
    edited August 2020
    Since you are working on a balcony, and can therefore afford to cosset your plants a bit, I would make an effort to give the lavender what it needs rather than making do. A mix of John Innes no. 2 or bagged topsoil, and horticultural grit or perlite would probably be a better long term potting mix for lavender. 
    "What is hateful to you, do not do to your neighbour". 
  • BorderlineBorderline Posts: 4,700
    I agree with Loxley there. Old multi-purpose compost gets very light after breaking up the small roots. In my opinion not any good apart from using on border soil as a soil conditioner or used for small seedlings. I have grown Lavender in the past with just multi-purpose compost and they did not grow well at all, they were very stunted. I suspect, with used multi-purpose compost, it will be the same.
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