As promised, here it is the second part on how to grow healthy plants. The first step to have a healthy culture is prevention; you should start before planting. Clean and disinfect substrate, pots, pipes and growing chamber. Be thorough, especially if you had any disease in your previous crop. In this case I would advise to throw away the substrate and use a new one. Know your seeds. It is very risky to plant seeds from unknown origin because the seeds mark the upper limit of the crop you can get: good genes matter. Even if you use healthy and clean seeds it is advisable to treat them also; read on to know how. Follow best practices when working in the culture: clean and disinfect your tools and never bring a plant from the outside into an indoors culture. Here it is a step by step guide on how to prepare your culture and seeds.
1.Disinfecting the culture chamber.
Remove all the plant residues from last crop and make space for a thorough cleaning. Use disinfectant (eg 20% bleach and detergent) cleaning well every corner. Let it work for 10 minutes and then rinse with water. Tip: bleach (sodium hypochlorite) is a commonly used product but it is dangerous nonetheless so be careful to ventilate the room during your cleaning. Avoid inhaling the harmful fumes. If you never had disease problems with previous crops or do not want to use bleach for whatever reason, you have alternatives: use potassium soap and water or spray peroxide concentrated at 30%. It is usually enough.
If you want to reuse the pots from last cycle, you should remove the substrate and wash them thoroughly. Also you can sanitize them by putting them overnight in a bucket with bleach concentrated at 20%: we want to make sure that nothing is left alive on them. Afterwards, rinse them with clean water. Tip: It is important to rinse repeatedly to remove all the rests of disinfectant once it has done its thing, especially when using bleach: some plants are very sensitive to chlorine.
3.Disinfection and chemical scarification of seeds
In the case of seeds you get two for one: at the same time you disinfect to avoid problems with fungi, you get a faster germination. How to do a chemical scarification? It’s easy. First prepare a solution with 1 part of bleach in 9 parts of water. Use any commercial bleach with no detergent, suitable for disinfecting water. Douse the seeds in this solution for 20 minutes. If the seeds come from plants which had fungus problems, you can use a more aggressive treatment submerging the seeds for 5 minutes in a mix of 1 part of bleach to two parts of water. After that, rinse the seeds three times with mineral or distilled water to wash away any rest of bleach. Boiled water will also do. The important thing is that the water is sterile. Never use seeds with plants that had a virus transmitted disease. Many virus are transmitted through the seeds and we cannot do much to eliminate them. Quite often the virus are within the embryo itself.