High numbers of small plants in a Sea Of Green is wasteful and tedious when you always have to buy new soil. If it can be continually used, is there anything special that I need to do to it besides flushing it?
Trailer Park Hill,
The safest way to grow an indoor ?soil? garden is to use pasteurized organic planting mix. That way you know that any pathogens, insect eggs and weed seeds in the mix have been destroyed. The soil is blended and ready for use.
If your garden is unhealthy, there is no choice ? the planting mix should be changed. The temptation comes when you have a planting medium that has just been supporting healthy plants. The easy answer is to use it outside, mixed with your soil or in raised beds. Unfortunately, most people don?t have that option. Another disposal option is the local community garden. Make sure there are no leaves in the mix.
All of this begs the question: can the soil be reused? The answer is yes. Planting mix can be reused. If it is a mix high in nutrients, most of them have probably not been used up after three months, especially if you were fertilizing during the growing cycle. After harvesting your soil, you will probably find that it is short 25%, so new mix has to be added. Some growers prefer to remove another quarter to a half of the old mix and replace it with new.
In commercial establishments, mix is reused after being steam pasteurized. However, the smallest pasteurizer costs about $600. You mentioned rinsing the mix, but that would dissolve many of the water soluble and semi-soluble nutrients. You have the option of reusing the old mix straight, or finding other uses for it. There is reason for some apprehension. What if there are harmful organisms that have colonized the mix? Is it worth risking a crop that takes so much time and effort to save the few dollars that the mix costs? Is it worth using new mix for the peace of mind knowing that you are starting clean?
If you really want to know, you could run an experiment. Plant some of the plants in the old mix straight. Put some in a 50/50 mix of old and new mix, and place some in new mix. See which plants do best. If you do this, please send me your results.
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