Some plants take so long to mature that even if started from seed in the garden at the beginning of the season, they would still not be ready to harvest at the end of the season (Brussels sprouts, for example).
Transplants. You can start a garden quickly with transplants and harvest crops sooner than with seeds. Small plants purchased from a garden center, catalog, or online provide a way to overcome seasonal limitations. Some plants take so long to mature that even if started from seed in the garden at the beginning of the season, they would still not be ready to harvest at the end of the season (Brussels sprouts, for example). Except for tomatoes, which can be planted slightly deeper, transplants should be planted in the ground at the same depth they were in the container. Disadvantages to using transplants include the increased cost compared to seeds and the limited number of varieties. Root crops (such as carrots, radishes, and beets) do not transplant well.