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Growing vegetables in vermiculite and perlite

hello folks,

I've been attempting to grow seedlings of mixed lettuce and spinach in a mix of 50:50 vermiculite and perlite. I've been adding fertiliser regularly, everything sprouted but things seem to have stopped (or maybe I'm being impatient?) and the seedlings look a little yellow to me. A few have sprouted extra leaves, but not many. Any suggestions? I might be over- or under- fertilising, or perhaps using the wrong thing (just simple Miracle-Gro, bright blue crystals). 

I'm no expert (sure you can tell) so even simple advice is welcome.

Left and right sections have mixed lettuce, middle section is a type of spinach (or chard - can't remember!)


  • punkdocpunkdoc Posts: 13,277
    My question, would be, why? Whats wrong with soil?
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  • FairygirlFairygirl Posts: 50,346
    Expensive too!
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • NollieNollie Posts: 6,773
    Well, being generous and assuming you have no access to soil or compost, but had a few bags of perlite and vermiculite to hand, as those are fairly inert growing mediums, designed merely to aid drainage and aid water retention of a soil/potting mix, all your plant nutrient needs rely on what you feed them, a bit like hydroponics. Miracle grow and the like are designed to boost plant growth in said soil/potting mix, so may be entirely unsuitable. So research the hydroponic nutrient needs of those particular plants.

    Your troughs look smart, but where is the drainage? It could be a boggy, oxygen-deprived hostile environment in there. Also, most plant pots, etc., are black or dark-coloured to exclude light, as roots need to grow in the dark.

    Looks like you are growing indoors, do the plants have enough light?

    A few things to think about.

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  • Thanks for the feedback. It’s something I did when I was a kid, many moons ago, and we had vegetables growing for months, particularly spinach / chard. I was keen to see if I could do it again. I think would be classified as hydroponics but not sure.

    I've been watering very carefully to avoid it getting boggy.

    I wonder if anyone could advise if the slight yellowing colour is a possible symptom of over-fertilising?

    This is all just a curiosity project but now that the seeds have sprouted I'm keen to see it through. The guy at the nursery was pretty curious too!
  • Pete.8Pete.8 Posts: 9,983
    I agree Nollie
    growing stuff in inert material is hydroponics and I would guess the plants are missing some important trace minerals.
    I think a feed for hydroponic plants will help - assuming light levels are good
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  • mrtjformanmrtjforman Posts: 331
    edited April 2020
    yep those blue pellets will be designed for soil - the soil helps break them down into food for the plants.
    In hydroponic setups you need to pay closer attention to the PH of your water and feed it hydroponic nutrients that have the feed in a ready to absorb form.

    the usual shop sold tomato and all purpose fertilizers which are cheap and cheerful and ideal for this purpose will not work in a hydroponic system. That said hydroponic nutrients are cheap too - they just require you have a degree in water chemistry compared to the good ol tomato feed which is just as matter of reading the instructiions on the bottle and pouring it on.

    You hear good stories of hydroponics and it can be highly rewarding but those are the growers that like said practically have a degree it takes that long to understand the complications of growing hydroponically.

    Most give up on the idea because although results can be great, the knowledge needed to succeed is vast and there is far more effort than people realize. Maybe not with vermiculite and perlite. I love perlite btw, i mix it in with all my soils, still can be classed as soil if it has perlite mixed in so you get the benefit of the perlite and the benefit of the soil without having to muck about with hydroponics and what it requires.
  • FairygirlFairygirl Posts: 50,346
    I'd worry about the 'no drainage' containers. You really have to know what you're doing with that alone.
    I'd agree with @Pete.8 too. You'd need the right feeds. Those foods you're using are designed to act, and react, with soil. The soil temps are also a factor in how it's released, so I'd imagine it will be very different in that context.
    It's a place where beautiful isn't enough of a word....

    I live in west central Scotland - not where that photo is...
  • Thanks for your help everyone. It’s just a curiosity project more than anything else. It took me a long time to even figure out what the growing medium was called, and it looks like even the hydro experts don’t use it much any more, preferring alternatives like rock wool. (I think it's what we used when I was a kid, but that was a while ago now!)

    Another reason was to try growing inside the house without soil - I wondered if it would mean fewer bugs, which can be a problem for me.

    I was worried about the fertiliser and it’s been suggested that I add a solution of seaweed and blood and bone, and maybe even fish, to add the nutrients it won’t get from the soil. This, with the Miracle Gro, should help. Fortunately they’re all things I have on hand. Worth a shot.

    If it doesn’t work, I’ll just add it to my potting mix. My soil seems to clump quite a lot and this seems to help keep it a bit looser (I throw a handful in each pot).

    Cheers everyone! Really appreciate the help. I may post another photo if this works, who knows ...

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