How to Prepare and Fill Soil in Vegetable Garden Pots

To prepare containers for growing vegetables you will need four things: soil, dolomite, fertilizer, and water.

Potting Mix: The best soil for growing vegetables in containers is not actually labeled “soil”.  Instead look for “potting mix”.  Potting mix has more organic matter compared to regular soil.  It allows roots to spread easily and holds moisture; both are important to growing vegetables in planter pots and containers.  Potting mix is typically be composed of things like:

  • peat moss (sphagnum)
  • coir
  • perlite
  • vermiculite

Dolomite: Dolomite is crushed rock that is used to raise the pH of potting mix, which is naturally acidic, to near neutral levels, which most vegetable plants like.  Dolomite has both calcium and magnesium which are both vegetable plant nutrients.  Add about 2 cups of dolomite per 1.5 cubic feet of potting mix.

Fertilizer: You can use most granular fertilizer.  Each of the 3 numbers (nitrogen – phosphorus – potassium) on the fertilizer should be between 3 and 15.  Add two to three cups of fertilizer per 1.5 cubic feet of potting mix.

Water: Tap water from the sink, or water from the hose are fine, or you can collect rainwater.

Once you have these supplies together, start filling your pot.  The pictures show an Earthbox which is a self-watering planter similar to the City Picker planter. If you don't have a self-watering planter, make sure there are drainage holes.

1. If you have a self-watering planter, pack potting mix into the corners first.

2.  Then fill the container with potting mix up to about 2 inches from the top.  Sprinkle water to keep things moist.

3.  Distribute your dolomite across the surface.  Then fill to near the top with more potting mix.

4.  Make a shallow trench or hole (a few inches deep) in the potting mix, next where you’ll be planting your plants, and fill it with fertilizer.  Cover it with some more potting mix.

5.  Plant your vegetable seeds or plants near to the fertilizer, but not right on top of it.  The plant roots will reach out to access it. 

6.  Water your vegetable planter or pot well.  For self-watering containers, pour water into your fill-tube.  For regular containers, gently water across the top.