Use of Mineral Oil to avoid Evaporation

I was given 2 Cyperus alternifolius (umbrella papyraus) or similar cuttings by my mother. They are effectively my first ever plants - I do not yet have green thumbs.

I am growing them reasonably successfully in 2 jam jars with a decent amount of soil, and I have then been keeping them well watered with approx 3-4 cm of standing water above the soil level. They both now have 1 new growth stem, which are both opening into umbrellas.

The problem: I need to leave them without supervision for 1 month. I think 4cm of water might just last them that long, but I do not want them to dry out. If I carefully add a thin layer of mineral oil to the top of the top of the standing water, this will prevent a significant amount of water evaporation. However - Will it damage the plants? I've seen that mineral oil is used as a pesticide without damaging plants, but this scenario might be a bit different.

All thoughts and ideas are welcome.

Many thanks.


  • DovefromaboveDovefromabove Central Norfolk UKPosts: 58,475

    I'd just give them a couple more centimetres of water and put them out of the sun.  They're pretty tough plants and in their native environment cope with fluctuating water levels.  

    I don't like the idea of adding oil to water.  

    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh

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