Gravel Trays


I'm new to growing my own food and greenhouse problems, and would like to ask about gravel trays.

I got some growbag trays,  filled them with gravel and stood my tomatoes in pots in the tray. Now I've notice that the gravel is going green. I can understand why, the moist warm environment has encourage an algea growth on the gravel. Just want to know if this is okay for the tomato plants and is there anything I can do about it? Or do I just ignore it?

Thanks in advance


  • weejennyweejenny Posts: 391

    I would say its ok, not alot you can do now anyway its there. Keep your greenhouse well ventilated. I dont shut my greenhouse when overnight temperatures are 15c or  more. Its only 5c with us at the moment in the Scottish Highlands so not leaving mine open for a while yet. But see what others think too

  • Zoomer44Zoomer44 Posts: 2,935

    I agree with weejenny. It might also help to try and keep the humidity down. I pour my grey water on the floor of the GH, I've a gravel path down the centre which is regularly doused down with water, if you use washing up water, just make sure any food in the water isn't poured out as this would encourage vermin.

  • WelshonionWelshonion Posts: 3,115

    Zoomer, I don't understand your post.  You suggest keeping the humidity down by pouring water all over the place?


  • PalaisglidePalaisglide Posts: 3,181

    I think we are talking two different things here, like Zoomer I run water over the pave walkway in the greenhouse for humidity when the weather is hot, I also keep several cans full of water warming up to water the plants next day. That is also for humidity which is needed for most greenhouse plants.
    Now the gravel trays, the idea is to have the gravel damp so it is humid around the tomato's which they need. I would suggest taking a trowel and turning the gravel round the pots every couple of days, this will disturb the growth which will be harmless but unsightly, bringing fresh gravel to the top and let it dry out a little by keeping the water low in the gravel trays.
    My tomato pots sit on a bed of gravel which I take the rake to a couple of times a week disturbing the small seedlings that seem to want to grow and clearing any weeds, chick weed seems to love greenhouse gravel, a run over with the Dutch hoe sorts that out.
    Air movement is essential in a greenhouse so I have extra vents which I can open when needed and on very hot days (if ever) I use a fan to move the air.
    Hope this will help but you will always get moss either on pots or the gravel when you have humid warm air.


  • Zoomer44Zoomer44 Posts: 2,935

    I've just re-read Tina's post. Mine does sound a contradiction, Frank puts it better, my point was good ventilation and humidy are  both important to keep a check on in the GH, which is especially true on particularly hot days, the down side  for having to much moisture in gravel trays results in algea forming, hence why I was suggesting pouring water on the floor of the GH instead, but didn't explain it very well.

  • Shedfield LadyShedfield Lady Posts: 4

    Using a gravel tray, do I water tomato plants from the top or put water into the gravel?

  • T.E.C.HT.E.C.H Posts: 1

    I submerge a small 9cm pot in the soil of the tomato plant, and apply feed into the 9cm - feeding the roots directly and avoiding foliage splash. This will then feed your tomato more and the gravel less.

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