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Miracle Grow ............ and little black flies!

The Bird LadyThe Bird Lady Posts: 225
in The potting shed
I have starting to use Miracle Grow compost for the odd pot outside and also with a few indoor plants, including two office plants.  I often mix it with other compost. Recently, we have noticed small black flies in the house, not huge amounts but enough to wonder where they've come from.  Embarrassingly, the office plants also have these and as the 'plant person', it falls to me to sort it.  I've not had this problem before, should I repot?  It seems a bit drastic.

Posts

  • Pete.8Pete.8 Posts: 11,340
    probably fungus gnats which are drawn toward damp compost of any type.
    They don't usually cause much damage, but they can be annoying.
    You can let the compost dry out a bit which will deter them, or put a layer of gravel on top of the compost to stop them getting down to the compost

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • wild edgeswild edges Posts: 10,497
    Yeah I used some Miracle Grow houseplant compost recently and had a massive outbreak of Fungus Gnats too. They're not the only guilty brand either sadly as I've seen it happen from other big manufacturers too. If it's just small numbers then just water the plants from below and keep the soil surface bone dry and they'll probably go away. Otherwise sticky traps work well but need to be mounted horizontally to trap such small flies. I tend to hoover up all the adults I can find for a few days and then water from below to prevent further outbreaks. A top-dress of fine gravel over the soil surface can also help deter them as it's the soil they like.
    Be aware that sticky traps can catch more pets and small humans than flies if you're not careful.
    If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
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