Aussies Living Simply

What's going on with my soil?

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    Here’s the situation: at the front of the house we have a small courtyard and I use white polystyrene boxes to grow tomatoes, lettuce, leeks, strawberries and some herbs. The tomatoes have been doing particularly poorly, in fact I only got two tomatoes off two bushes (grosse lisse) and they were yellowing and wilting so I decided to pull them up.

    Once I did, I discovered the soil in the box has turned a kind of grey colour. There are a lot of slaters – mostly baby ones, but apparently my garden’s the place to hang out if you’re a slater so no surprises there. But they don’t usually change the colour of the soil, do they? It also appeared dusty, even tho’ the plants have had enough water, they got watered every night. The texture of the soil was kind of spongy too.

    I checked out the root system of the tomatoes, and while they seemed a little shallow-rooted, they didn’t appear that knobbly as I would have expected with nematodes. Then I decided to look in the box next to the tomatoes, which used to have the leeks in it. Same story there. The strawberry box is fine, as is the one where I pulled out the peas recently.

    The camera has no battery and it’s pretty poor resolution anyway, so I’m afraid all I can offer is the description for now. The mix I put in when I planted the tomatoes was potting mix, with a little multimix (cow and sheep manure) mixed in. They’ve also had some potash sprinkled around them a couple of times.

    Any thoughts would be appreciated. I’m kind of bummed that I’ve had so many failures in the vegie patch this season, and am just hoping that the other tomato plants I have won’t suffer the same fate.


    sounds like the boxes have got to dry and hot and the potting mix has heated up and become ash which can hapen with potting mix


    some potting mixes become water repellent and turn that greyish colour is they’ve dried out a few times. When it becomes water repellent, when you water the plant the water penetrates the top couple of mm of soil but the rest runs off down the sides of the pot, leaving the roots dry.

    It’s a good idea with vegies in boxes or pots to poke you fingers into the potting mix to check that the water is penetrating. If you find the potting mix is dry, even after you’ve watered, get a large container of water and place the pot in it. You’ll see bubbles in the water as the air spaces are expelled. You’ll need to leave it in a few hours to really soak the soil. When you get it out, let it drain properly and place some mulch over the top of the mix around the vegies. This will help retain the moisture.

    Completely saturating the soil is often enough to fix the situation but sometimes you need to do it 2 or 3 times.

    Lyn Bagnall

    Did you get your soil problems sorted out Becca? This thread appeared when I was having phone line probs and I couldn’t join in. I have been wondering if things had improved for you because you seem to be getting disheartened.

    If you want to grow good veggies in boxes or pots don’t just use garden soil. It doesn’t work as well in containers as it does in garden beds and becomes compacted and sour.

    We find that our veggies grow well in a mix of one part washed river sand, one part moistened cocopeat, one part matured compost, and one part organic garden soil – all thoroughly mixed together. We put a single layer of wet newsprint over the bottom of the box to prevent the mix washing through the holes. Remember pots and boxes will require watering more often than garden beds. Follow Forest’s watering instructions above, and use liquid fertilisers at half the strength you apply them on garden beds but apply it twice as often. This will prevent fertiliser burn. If you are growing in hot, dry conditions add 1/5 of a part of bentonite to the mix. This is an absorbent volcanic clay and will help the mix retain more water.

    If you can’t make your own mix, use a good quality organic potting mix instead. Never use cheap mixes – it is false economy. They are full of rubbish and quickly become water-repellant resulting in poor growth. πŸ™‚


    Hi Lyn, thanks for replying! I don’t even bother using plain garden soil to grow stuff in the garden – Perth soil is notoriously sandy and poor so I use raised beds with compost and manure. The potting mix I generally use is a Waldeck’s one (I’m not sure if Waldeck’s is national or not, but it has the red Aust standard ticks on it, anyway). I’m thinking that the boxes must have become water repellent. It was just strange that it happened only in those boxes but not in the pots, which are smaller and which I would have thought would heat up more. Anyway, I’ve kept on with lettuce and herbs and I’ll start with some winter vegies in a few weeks when things settle – and hopefully cool – down. We’re hoping to move at the end of the year, so I’m looking forward to a new challenge of having a slightly bigger garden. The place we’re looking to move to is further south and has cooler summers, so that will be not only a nice change but also bring with it other challenges, I imagine!

    thanks again.

    Lyn Bagnall

    Potting mixes with all the ticks should be fine for growing things in boxes but I always mix some dampened cocopeat or worm castings through the potting mix for boxes as they do help to retain moisture and the worm castings will also help you to grow champion veges.

    Lucky you, Becca, moving to a larger garden with cool summers. You’ll be able to grow raspberries. We grew the tropical raspberries here but they weren’t a patch on the real thing, so I pulled them out. Don’t worry about the challenges in your new home. With an army of advice providers on ALS, you will manage magnificently. πŸ˜€

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