Would plants grow better in potting soil with phosphorous or ordinary garden soil?

Answer 1

Phosphorus affects the blooming of plants. It is one part of a three part table that rates your fertilizers. Fertilizers have a rating... like 20 20 20 or 10 8 6, like that. The first number is nitrogen which helps green things up, Phosphorus is the middle number and the last is potassium which helps strengthen the whole plant. A good potting soil is a healthy start. After the plants have grabbed on, then you can feed the plant with an appropriate fertilizer. A general one helps the whole plant, If you want flowers to be prolific, like on annuals that bloom all summer, a bloom food is good. Fertilizers are now being made for all kinds of specific plants..... evergreens, fruiting plants, acid lovers, etc. This is just the quick and basic answer, but I hope it helps.

Answer 2

Potting soil is meant for pots. Garden soil is for the landscape.
Most potting soil (other than the really cheap stuff) has what the plant needs if the plant is going to be placed in a pot. (perlite for aeration, sphagnum for water retention etc.) Some even have fertilizer in them. Osmocote can be used in the garden soil or the potting soil. That stuff is good for everything!