As you prepare to create your spring flower containers you will most likely need to purchase a bag of potting soil while you are at the garden center. But, have you ever looked at the numerous options of soil available? How do you know which one to purchase? What specific ingredients should a good quality potting soil contain?
Well, first let's learn a horticulture term. A growing
medium is the substance in which the growing of a crop is accomplished. A growing medium is important to overall plant success, as it serves to support the plant, provide nutrients and oxygen, and absorb water. These four items (support, nutrients, oxygen, and water) are essential requirements to any plant in any growing condition.

More specifically, when looking for a growing medium for plants in a container you should seek to find a product that says "Potting Soil or Potting Mix". Potting soils should be used for container planting and container planting alone. Potting soil mixtures should not be used as general landscape gardening soil. Furthering, gardening soil, compost, manures, mulches, etc. should not be used for container planting. The reason being, general gardening soil, contains many heavy additives such as clay and sand. These two examples of growing mediums (sand and soil) can suffocate the nutrients from your container plants.
Now that you have narrowed down your selection at the garden center, you should just be looking at bags of planting media that says "Potting Soil or Potting Mix". Remember the potting soil must provide support, nutrients, oxygen, and water to our plant. Most potting soil mixtures consists of three ingredients: peat moss, pine bark, and perlite.
Peat moss is grown and harvested from peat bogs in Canada and the Northern United States. Peat moss provides great moisture retention abilities which allows for the potting soil to retain water and make that water available to the plant.
Pine bark is derived from trees when trees are harvested to make paper. Pine bark and any other bark material provides structure to the growing medium as well as adds another dimension to the growing medium creating more pore space for oxygen and water to travel to the plant roots.
Perlite is naturally derived from volcanic rock. It is mined and then heated to a very high temperature until it expands and becomes like a piece of popcorn. Perlite is white in color and very light. Perlite helps to increase aeration as well as create a light and fluffy medium that is not overly dense.
Potting mixtures should be light and fluffy. Oxygen is essential to plant growth. Oxygen helps to break down food through a processes of respiration to generate growth. Most of a plants respiration occurs in the roots. Pore space provided through a light and fluffy growing media provides plant roots with oxygen for the respiration process. Additionally, when you fill the planting container with potting soil, it should be moist but not saturated. Water must be accessible for the plant roots, but excess water can become too heavy and cause the growing root system to rot.

Lastly, most potting soil mixtures contain three common nutrients for overall plant growth. Nitrogen (N), Phosphate (P), and Potassium (K). Nitrogen is mostly responsible for growth of the leaves of the plant. Phosphate encourages root growth, flower and fruit development. And Potassium helps the plant to complete all of its general plant functions.
In conclusion, when preparing to plant your spring containers, be sure to purchase "Potting Soil or Potting Mix". The potting soil mixture should be light and fluffy and moist. Avoid heavy media such as sand, clay, or compost, etc. Rather, a mixture of peat moss, pine bark, and perlite offers good quality support, nutrients, aeration, and moisture retention to your container plants. Quality potting soil will ensure your beautiful container arrangements is healthy and beautiful for many weeks to come.