If the soil packs down, plant growth will be reduced. This fact explains why it's not a good practice to scoop garden soil into containers for planting. The soil becomes compacted and drains poorly unless it is amended with a high proportion of materials that encourage drainage. The pumice or vermiculite, which contribute to keeping air spaces open, will be apparent as little white blobs in the mix. Finally, provide fertilizer for container plants.
Many gardeners incorporate a timed-release fertilizer when planting.
This helps, because most potting soils in bags do not contain any plant nutrients. Check the label when purchasing planting soil. The plants you buy, looking green and healthy, have received regular doses of fertilizer at the nursery while growing. As well as providing time-release fertilizer upon planting, it's important to use a liquid fertilizer about once every three weeks during the summer growing period. Do not over-fertilize with too much nitrogen, which will lead to leaves rather than flowers and fruit.