We have a small greenhouse/polytunnel (4×5×2,5 m) and this year is first season for growing tomatoes and peppers in it.

However, this year was challenging regarding weather and diseases. Each time there was rain and too much humidity - plants got sick (probably blight). We managed to save many plants and have some healthy fruits but there is concern for next season.

Is there a organic/healthy way to disinfect inside greenhouse (greenhouse cover/nylon, structure and soil) so next year there is less chance of such problems?

  • Bleach/water or borax/water for the fungus, then air? More venting next year? Sep 1, 2023 at 22:36
  • It was well vented and 99% of time sides, top windows and doors were fully open. Shading net was put as soon as temperatures started reaching 30°C, watering was precisely directed around base of plants in order to prevent splashing. There is always light breeze flowing thru greenhouse. I'd say all requiremets were met... Sep 2, 2023 at 5:05
  • @YosefBaskin Regarding ingredients for disinfection do you have a 'recepy' regarding ratios, howvto apply... ? Care to post it as answer? Sep 4, 2023 at 22:53
  • I do not have a recipe, but Google may have one. A quicker-draining potting mix (sandier, airier) will reduce humidity. Sep 4, 2023 at 23:00

1 Answer 1


If it was indeed well ventilated and the roots were not permanently drenched in water then the pathogens (bacteria and fungi) could have arrived via air, insects or birds.

  • You can't do much about insects but perhaps bird netting might help.
  • And start spraying with copper before the rainy season - follow the instructions on the packet which should be tuned for your location.

Disinfectant methods have already been mentioned by @YosefBaskin

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