I have a bunch of old-school mineral fertilizers that I would like to use for container plants. The problem is that the dosage on them is grams/m2, lets say for simplicity it is 100 grams/m2. How do i convert that dosage for container plants ? Taking 0.2 meters as depth (and this is pretty low i think) 1 m2 with 0.2 meters depth becomes 200 liters of volume. My biggest container is 20 liters, so i only need to put 10 grams of fertilizer per container ? This seems pretty low, especially since this is supposed to feed the plant for 6-8 weeks.
The one fertilizer I use inside and out is MiracleGrow. There are several different mixtures of this stuff, but many say:
For Outdoor Plants: Mix 1 tablespoon of Miracle-Gro for every gallon of water. For Indoor Plants: Mix 1/2 teaspoon (not tablespoon) per gallon of water.
I use a teaspoon per gallon indoors. Of course, your mileage may vary, but half strength is a good place to start.