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This year I wanted to experiment with growing edible salads, Chinese cabbage, spinach, lettuce and herbs at home in pots under artificial lighting, so I got the seeds, but not the soil (or lights, or pots) yet. So far I've been using any random "soil for flowers" and all the seeds I have planted have grown to maturity, and I can't really complain. But maybe I could be losing out on potential leaf mass, so I wanted to ask: Is picking the most optimal soil makes a noticeable difference, or starting with just any random "flower soil" is a safe bet and I need not spend more time looking for the best?

If the soil composition is indeed an important enough factor, then out of this range of soils I can find at my store, which one would be the best for a simple "plant and forget" (without re-upping nutrient contents for the duration of the useful growth) approach for edible greens?

  1. N 120, P 140, K 230, pH 5.8-6.8;
  2. N 135, P 180, K 270, pH 5.5-6.5;
  3. N 135, P 180, K 315, pH 5.5-6.5;
  4. N 170, P 200, K 320, pH 5.0-6.8;
  5. N 180, P 180, K 225, pH 5.5-6.5;
  6. N 230, P 300, K 350, pH 5.5-7.0;
  7. N 100-180, P 100-180, K 130-260, pH 5.5-6.5;

The last soil bag has these wide ranges, and looks like a very generic brand of soil, so I don't know if it's safe to risk it even in a general case, but maybe this one is actually the best of them, for all I know.

Additionally, would I be missing out on a noticeable amount of edible plant mass if I never added any nutrients after planting in a pot? If the difference is in the range of 5-15%, I think I can ignore it, but if it's high, like >40%, then I'll look into how to keep the nutrient contents of the soil at an optimum for food greens.

user1306322
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  • if the question is not valid or there's too much in one question, please tell me how to break it into better parts – user1306322 Nov 05 '20 at 12:17
  • As a general rule, nitrogen is required for green leaf growth and potassium for flower and fruit production. All your quoted "flower soil" fertilizer compositions look higher than necessary in K for green vegetables, though it probably won't do any harm. Some flowers only "flower" well as a result of too *little* nitrogen to keep growing into a bigger plant. – alephzero Nov 05 '20 at 13:29

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